Sensor Catalog
Introduction
NVE GMR Sensor Applications
•
•
•
•
•
•
•
•
•
•
•
Position of Pneumatic Cylinders
Position in Robotics Applications
Speed and Position of Bearings
Speed and Position of Electric Motor Shafts
General Field Detection in Implantable Medical Devices
Wheel Speed Sensing for ABS Brake Applications
Transmission Gear Speed Sensing for Shift Control
Low Field Detection in Currency Applications
Current Sensing in PCB Traces and Wires
Overcurrent and Short Circuit Detection
Vehicle Detection for Traffic Counting Applications
Table of Contents
Introduction to NVE GMR Sensors .................................................................................................. 4
GMR Materials Overview............................................................................................................. 5
Basic Sensor Design ..................................................................................................................... 7
Signal Processing........................................................................................................................ 11
AA and AB-Series Analog Sensors ................................................................................................ 12
AA Sensors ................................................................................................................................. 14
AAH Sensors .............................................................................................................................. 16
AAL Sensors............................................................................................................................... 18
AAV Sensors .............................................................................................................................. 20
AB Sensors ................................................................................................................................. 24
ABH Sensors............................................................................................................................... 26
GMR Switch Precision Digital Sensors .......................................................................................... 28
GMR Switch Product Selection Guide ....................................................................................... 30
AD0xx-xx to AD7xx-xx ............................................................................................................. 36
AD8xx-xx to AD9xx-xx ............................................................................................................. 40
ADH0xx-xx ................................................................................................................................ 44
GT Sensors .................................................................................................................................. 46
ABL Sensors ............................................................................................................................... 47
AKL Sensors............................................................................................................................... 52
Circuit Board Sensor Products........................................................................................................ 56
AG21x-07 Cylinder Position Sensors ......................................................................................... 56
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Introduction
AG-Series Currency Detection Sensors...................................................................................... 59
Peripheral Integrated Circuits ......................................................................................................... 61
DB001-00 Series Power Switch IC............................................................................................. 62
DB002-02 Series Power Switch IC............................................................................................. 65
DC-Series Voltage Regulators.................................................................................................... 68
DD-Series Signal Processing ICs................................................................................................ 70
Evaluation Kits ............................................................................................................................... 73
AG001-01 Analog Sensor Evaluation Kit .................................................................................. 74
AG003-01 Current Sensor Evaluation Kit .................................................................................. 75
AG910-07 and AG911-07 GMR Switch Evaluation Kits........................................................... 76
AG920-07 GT Sensor Evaluation Kit......................................................................................... 77
Application Notes for GMR Sensors .............................................................................................. 78
General Comments ..................................................................................................................... 79
Competitive Technologies .......................................................................................................... 79
GMR Material Physics ............................................................................................................... 80
GMR Materials Types Manufactured by NVE ........................................................................... 84
Temperature Characteristics of GMR Sensors............................................................................ 85
Hysteresis in GMR Sensors ........................................................................................................ 89
GMR Magnetic Field Sensors (Magnetometers) ........................................................................ 94
GMR Magnetic Gradient Sensors (Gradiometers)...................................................................... 96
Magnetic Reference Information ................................................................................................ 98
Signal Conditioning Circuits ...................................................................................................... 99
Noise In NVE Giant Magnetoresistive Sensors ........................................................................ 105
Use Of GMR Magnetic Field Sensors ...................................................................................... 106
Application Notes for GT Sensors............................................................................................ 109
Measuring Displacement .......................................................................................................... 116
Current Measurement ............................................................................................................... 117
Magnetic Media Detection........................................................................................................ 126
Currency Detection and Validation .......................................................................................... 127
Appendix ...................................................................................................................................... 131
Package Drawings and Specifications ...................................................................................... 131
Recommended Solder Reflow Profile ...................................................................................... 134
Magnet Data ............................................................................................................................. 135
Part Numbers and Marking Codes............................................................................................ 137
Definitions and Conversion Factors.......................................................................................... 140
NVE Company Profile.............................................................................................................. 143
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Introduction
Introduction to NVE GMR Sensors
In 1988, scientists discovered the “Giant Magneto Resistive” effect—a large change in electrical
resistance that occurs when thin, stacked layers of ferromagnetic and non-magnetic materials are
exposed to a magnetic field. Since then, many companies have sought to develop practical applications
for this intriguing technology. NVE Corporation has taken the lead by developing the first
commercially available products making use of GMR technology, a line of magnetic field sensors that
outperform traditional Hall Effect and AMR magnetic sensors.
NVE introduced its first analog sensor product in 1995. Since then, our product line has grown to
include several variations on analog sensors, the GMR Switch line of precision digital sensors, and
our newest products, the GT Sensors for gear tooth and encoder applications. In addition to these
products, NVE offers printed circuit board assemblies for pneumatic cylinder position and currency
detection applications as well as peripheral integrated circuits designed to work with our GMR sensors
in a variety of applications. Finally, NVE remains committed to custom product developments for
large and small customers in order to develop the best possible sensor for the customer’s application.
NVE magnetic sensors have significant advantages over Hall Effect and AMR sensors as shown in the
following chart. In virtually every application, NVE sensors outperform the competition—often at a
significantly lower installed cost.
Benefits:
GMR
HALL
AMR
Physical Size
Small
Small
Large
Signal Level
Large
Small
Medium
Sensitivity
High
Low
High
Temperature Stability
High
Low
Medium
Power Consumption
Low
Low
High
Cost
Low
Low
High
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Introduction
GMR Materials Overview
The heart of NVE’s sensor products are the proprietary GMR materials produced in our factory. These
materials are manufactured in our on-site clean room facility and are based on nickel, iron, cobalt, and
copper. Various alloys of these materials are deposited in layers as thin as 15 Angstroms (five atomic
layers!), and as thick as 18 microns, in order to manufacture the GMR sensor elements used in NVE’s
products.
The following diagrams show how the GMR effect works in an NVE sensor using multilayer GMR
material. Note that the material is sensitive in the plane of the IC, rather than orthogonally to the IC, as
is the case with Hall elements.
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Introduction
NVE’s GMR materials are noteworthy in comparison with other GMR material types in that NVE’s
material cannot be damaged with the application of extremely large magnetic fields. GMR materials
from other sources often rely on keeping one of the magnetic layers internally magnetized, or pinned,
in a specific direction, and allowing the other layer to rotate and thus provide the GMR effect. In some
of these materials, an external magnetic field as small as 200 Gauss can upset this pinned layer, thus
permanently damaging the sensor element. Most of NVE’s GMR materials rely on anti-ferromagnetic
coupling between the layers; as a result they are not affected by extremely large fields, and will resume
normal operation after the large field is removed. NVE has recently introduced a production GMR
material with a pinned magnetic layer, this pinned layer uses a synthetic anti-ferromagnet for the
pinning, which cannot be upset at temperatures below 300ºC. As a result, NVE’s pinned GMR material
is not susceptible to upset problems.
The following chart shows a typical characteristic for NVE’s standard multilayer GMR material:
Notice that the output characteristic is
omnipolar, meaning that the material provides
the same change in resistance for a
directionally positive magnetic field as it does
for a directionally negative field. This
characteristic has advantages in certain
applications.
5100
Electrical Resistance (Ohms)
5000
4900
4800
4700
4600
4500
4400
4300
4200
-500
-250
0
250
500
Applie d Ma gnetic Fie ld (Gauss)
For example, when used on a magnetic
encoder wheel, a GMR sensor using this
material will provide a complete sine wave
output for each pole on the encoder (rather
than each pole pair, as with a Hall Effect
sensor), thus doubling the resolution of the
output signal.
The material shown in the plot is used in most of NVE’s GMR sensor products. It provides a 98%
linear output from 10% to 70% of full scale, a large GMR effect (13% to 16%), a stable temperature
coefficient (0.14%/°C) and temperature tolerance (+150°C), and a large magnetic field range (0 to
±300 Gauss).
In addition to manufacturing this excellent GMR material, NVE is constantly developing new GMR
materials. New products have recently been introduced which use three new materials: one with double
the magnetic sensitivity of the standard material, one with half the magnetic hysteresis, and one with a
synthetic antiferromagnet pinned layer designed for use in magnetic saturation. Some of these new
materials are suitable for operation to +225°C. Please see the application notes section of this catalog
for a complete description of the GMR material types available in NVE’s magnetic sensors.
NVE continues to lead the market in GMR-based magnetic sensors due to constant emphasis on
developing new or improved GMR materials and frequent new product releases utilizing these
improvements.
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Introduction
Basic Sensor Design
NVE manufactures three basic sensor element types: magnetometers, which detect the strength of the
applied magnetic field, gradiometers (or differential sensors), which detect the difference in the applied
magnetic field strength at two discrete points on the sensor element, and spin valve sensors, which
change in output with the angular difference between the pinned layer and the free layer of the GMR
material while the device is exposed to a saturating magnetic field.
These three basic sensor element types are described in the sections below.
Magnetometers
NVE’s magnetometers are covered by our basic GMR material and sensor structure patents and have
unique features designed to take advantage of the characteristics of GMR sensor materials. A
photomicrograph of an NVE sensor element is shown below:
5K GMR Resistors
(Sensing Elements)
Flux Concentrators
5K GMR Resistors
(Reference Elements)
The size of this IC is approximately 350 microns by 1400 microns. The sensor is configured as a
Wheatstone bridge. The serpentine structures in the center of the die and to the left of center under the
large plated structure are 5 kΩ resistors made of GMR material.
The two large plated structures shown on the die are flux concentrators. They serve two purposes.
First, notice that they cover two of the resistors in the Wheatstone bridge. In this configuration the flux
concentrators function as a shield for these two resistors, preventing an applied magnetic field from
reaching them. Therefore, when a field is applied, the two GMR resistors in the center of the die
decrease in resistance, while the two GMR resistors under the flux concentrator do not. This imbalance
leads to the bridge output.
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Introduction
The second purpose of the flux concentrators is to vary the sensitivity of the sensor element from
product to product. They work by forming a low reluctance path to the sensor elements placed between
them. NVE uses a “rule of thumb” formula to calculate the effect of the flux concentrators:
Field at sensor elements ≅ (Applied Field)(60%)(FC length / gap between FCs)
For the sensor shown in the previous photo, the length of each flux concentrator is 400 microns, and
the gap between the flux concentrators is 100 microns. Therefore, if the sensor is exposed to an applied
field of 10 Gauss, the actual field at the sensor element will be about (10 Gauss)(0.6)(400 microns /
100 microns), or 24 Gauss.
NVE uses this technique to provide GMR sensors with varying sensitivity to the applied magnetic
field. The following chart shows sensitivity ranges for some of NVE’s products. Sensitivity to the
magnetic field is indicated by the slope of each line:
400
350
Output (mV)
300
250
AA002
200
150
AA004
100
AA005
50
0
-150
-100
-50
0
50
100
150
Applied Magnetic Field (Gauss)
Maximum signal output from such a sensor element is typically 350 mV at 100 Gauss with a 5V power
supply. This compares to an output of 5 mV under the same conditions for a Hall sensor element, and
100 mV for an AMR sensor.
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Introduction
Gradiometers
NVE’s gradiometers, or differential sensors, rely on the field gradient across the IC to generate an
output. In fact, if one of these sensors is placed in a uniform magnetic field, its output voltage will be
zero. This is because all four of the bridge resistors are exposed to the same magnetic field, so they all
change resistance together. There is no shielding or flux concentration on a gradiometer. A simple
representation of a gradiometer is shown in the diagram below:
R4
R3
Gradiometer
Out-
(Differential Sensor)
R4
R1
R1
Out+
R2
R2
R3
Because all four bridge resistors contribute to the sensor’s output, at maximum differential field NVE’s
gradiometers can provide double the output signal of our magnetometer parts—approximately 700 mV
with a 5V supply. In practice, the gradient fields are typically not high enough to give this maximum
signal, but signal levels of 50 mV to 200 mV are common.
NVE’s GMR differential sensors are typically designed with two of the bridge resistors at one end of
the IC, and two at the other end. The spacing between the two sets of resistors, combined with the
magnetic field gradient on the IC, will determine the output signal from the sensor element. NVE
offers three standard spacings for differential sensors: 0.3 mm, 0.5 mm, and 1.0 mm. If a different
spacing is desired, contact NVE for development cost and schedule for a custom product.
The most popular application for differential sensors is in gear tooth or magnetic encoder detection. As
these structures move or spin the magnetic field near their surface is constantly varying, generating a
field gradient. A differential sensor, properly placed, can detect this movement by sensing the
changing field gradient and provide an output for each gear tooth or each magnetic pole (see the GT
Sensor section of this catalog for a more detailed explanation). Applications for these devices include
detecting the speed and position of electric motor shafts or bearings, automotive transmission gear
speeds, axle shaft speed in Anti-lock Braking Systems (ABS), or linear gear-tooth position.
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Introduction
Spin Valve Sensors
NVE’s spin valve sensors are designed using our synthetic anti-ferromagnet pinned layer. This pinned
layer is very robust, and not subject to upset or reset. The basic GMR material construction includes
the pinned layer and a free layer; the free layer can be influenced by an external magnetic field in the
range of 30 to 200 Gauss. The output of the sensor varies in a cosine relationship to the angle between
the free layer and the pinned layer.
As long as the external field strength is in the 30 to 200 Gauss range, the free layer in the GMR
material is saturated. It will therefore point in the same direction as the external field, while the pinned
layer remains pointed in its fixed direction. The diagram below shows a vector concept of the device
operation:
r
ye
La
ee
Fr
Ap
p
(3 lied
0t M
o 2 ag
00 net
Ga ic F
us iel
s) d
Pinned Layer
Angle Between Pinned
and Free Layers
Determines Electrical
Resistance of Sensor
Free Layer Aligns
with the Applied
Magnetic Field
The percent change of resistance available with this GMR material is about 5%. The output is a cosine
function over 360 degrees of angular movement by the external, saturating magnetic field.
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Introduction
Signal Processing
Adding signal processing electronics to the basic sensor element increases the functionality of NVE’s
sensors. The large output signal of the GMR sensor element means less circuitry, smaller signal errors,
less drift, and better temperature stability compared to sensors where more amplification is required to
create a usable output.
For the GMR Switch products, NVE adds a simple comparator and output transistor circuit to create
the world’s most precise digital magnetic sensor. For these products, no amplification of the sensor’s
output signal is necessary. A block diagram of this circuitry is shown in the figure below:
Voltage
Regulator
(5.8V)
Current Sinking
Output
GMR
Bridge
Comparator
The GMR Switch holds its precise magnetic operate point over extreme variations in temperature and
power supply voltage. This low cost product has revolutionized the industrial control position sensing
market.
Taking this approach one step further, NVE’s integrated GT Sensor products add low-gain
amplification and magnet compensation circuitry to the basic sensor element to create a powerful gear
tooth and encoder sensor at an affordable price.
NVE also offers certain peripheral IC products to help customers integrate GMR sensor elements into
their systems and meet rigorous regulatory agency requirements for safety and survivability. These
products include power switch ICs for switching large currents in industrial applications and voltage
regulator ICs for reducing wide ranging automotive and industrial voltage supplies to manageable ICfriendly levels. Both of these product types retain a “bulletproof” appearance to the outside electrical
world and resist damage from high voltage transients, reverse battery connections, and ESD/EMC
events.
For applications where a unique product is required, NVE’s in-house IC design group regularly does
custom designs for our customers. These designs range from simple variations on NVE’s existing parts
to full custom chips for one-of-a-kind applications. For applications where a unique electronic
functionality is required, please contact NVE.
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AA and AB-Series Analog Sensors
AA and AB-Series Analog Sensors
NVE’s AA and AB-Series analog GMR sensors offer unique and unparalleled magnetic sensing
capabilities. These sensors are characterized by high sensitivity to applied magnetic fields, excellent
temperature stability, low power consumption, and small size. These characteristics make them
suitable for use in a wide variety of applications from rugged industrial and automotive position,
speed, and current sensors, to low-voltage, battery-powered sensors for use in hand-held
instrumentation and implantable medical devices. The unmatched versatility of these basic magnetic
sensors makes them an excellent choice for a wide range of analog sensing applications.
The AA-Series sensors use NVE’s patented GMR materials and on-chip flux concentrators to provide
a directionally sensitive output signal. These sensors are sensitive in one direction in the plane of the
IC, with a cosine-scaled falloff in sensitivity as the sensor is rotated away from the sensitive direction.
Also, these devices provide the same output for magnetic fields in the positive or negative direction
along the axis of sensitivity (omnipolar output). All sensors are designed in a Wheatstone bridge
configuration to provide temperature compensation. Two packages are offered, an SOIC8 and an
MSOP8. These sensors are also available in die form on a special-order basis.
There are three families of NVE’s basic AA-Series sensors: the standard AA-Series, the AAH-Series,
and the AAL-Series. Each of these sensor families uses a different GMR material, with its own
characteristics. The comparison table below summarizes the different characteristics of the GMR
materials:
Parameter
Sensitivity to Applied Fields
Field Range of Operation
Hysteresis
Temperature Range
AA Series
High
High
Medium
High
AAH Series
Very High
Low
High
Very High
AAL Series
High
Medium
Low
Very High
The AB-Series sensors are differential sensor devices, or gradiometers, which take advantage of the
high output characteristics of NVE’s GMR materials. Two families of AB sensors are offered, the
standard AB-Series and the ABH-Series. They have operational characteristics similar to the AA and
AAH sensors described in the table above but with the bipolar linear output characteristics of a
differential sensor.
Within these different sensor families, customers can find an excellent match to their analog sensor
requirements.
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AA and AB-Series Analog Sensors
Quick Reference: AA and AB-Series
For comparison and product selection purposes, the following table lists all available AA and ABSeries analog sensors, with some of their key characteristics:
Magnetometers:
Part
Number
AA002-02
AA003-02
AA004-00
AA004-02
AA005-02
AA006-00
AA006-02
AAH002-02
AAH004-00
AAL002-02
Linear
Range
1
(|Oe |)
Min
Max
1.5
10.5
2.0
14
5.0
35
5.0
35
10.0
70
5.0
35
5.0
35
0.6
3.0
1.5
7.5
1.5
10.5
Maximum
Nonlinearity
2
(% Uni. )
Maximum
Hysteresis
2
(% Uni. )
Maximum
Operating
Temp
(°C)
Typical
Resistance
(Ohms)
Package
2
2
2
2
2
2
2
6
4
2
4
4
4
4
4
4
4
15
15
2
125
125
125
125
125
125
125
150
150
150
5K
5K
5K
5K
5K
30K
30K
2K
2K
5.5K
SOIC8
SOIC8
MSOP8
SOIC8
SOIC8
MSOP8
SOIC8
SOIC8
MSOP8
SOIC8
Resistor
Spacing
(mm)
Maximum
Nonlinearity
2
(% Uni. )
Maximum
Hysteresis
2
(% Uni. )
Maximum
Operating
Temp
(°C)
Typical
Resistance
(Ohms)
Package
0.5
0.5
0.5
2
2
4
4
4
15
125
125
150
2.5K
2.5K
1.2K
SOIC8
MSOP8
MSOP8
Sensitivity
1
(mV/V-Oe )
Min
Max
3.0
4.2
2
3.2
0.9
1.3
0.9
1.3
0.45 0.65
0.9
1.3
0.9
1.3
11.0 18.0
3.2
4.8
3.0
4.2
Gradiometers:
Part
Number
AB001-02
AB001-00
ABH001-00
Linear
Range
1
(|Oe |)
Min
Max
20
200
20
200
5
40
Notes:
1. Oersted (Oe) = 1 Gauss in air.
2. Unipolar operation means exposure to magnetic fields of one polarity, for example 0 to +30 Gauss, or -2 to -50 Gauss.
Bipolar operation (for example, -5 to +10 Gauss) will increase nonlinearity and hysteresis
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AA Sensors
AA Sensors
Features:
•
•
•
•
•
•
•
Excellent Sensitivity to Applied Magnetic Fields
Wheatstone Bridge Analog Output
Operating Temperature to 125°C Continuous
Wide Linear Range of Operation
Near-Zero Voltage Operation
DC to >1MHz Frequency Response
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
•
General Motion, Speed, and Position Sensing
Low Power, Low Voltage Applications
Low Field Sensing for Magnetic Media Detection
Current Sensing
Description:
The basic AA-Series GMR sensors are general-purpose magnetometers for use in a wide variety of
applications. They exhibit excellent linearity, a large output signal with applied magnetic fields, stable
and linear temperature characteristics, and a purely ratiometric output.
Pin-out
V+ (supply)
Functional Block Diagram
OUT+
pin 8,
V+(supply)
NVE
NVE
AAxxx
AAXXX-02
-02
Orientation
chamfer
Pin 1
shield
GMR
pin 5, OUT+
shield
OUT -
V- (ground)
Axis of Sensitivity
pin 1, OUT-
pin 4, V(ground)
Magnetic Characteristics:
Part
Number
AA002-02
AA003-02
AA004-00
AA004-02
AA005-02
AA006-00
AA006-02
Saturation
1
Field (Oe )
15
20
50
50
100
50
50
Linear
Range
1
(|Oe |)
Min
Max
1.5
10.5
2.0
14
5
35
5
35
10
70
5
35
5
35
Sensitivity
1
(mV/V-Oe )
Min
Max
3.0
4.2
2
3.2
0.9
1.3
0.9
1.3
0.45 0.65
0.9
1.3
0.9
1.3
3
Resistance
(Ohms)
Package
5K ±20%
5K ±20%
5K ±20%
5K ±20%
5K ±20%
30K ±20%
30K ±20%
SOIC8
SOIC8
MSOP8
SOIC8
SOIC8
MSOP8
SOIC8
2
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Die Size
(µm)
436x3370
436x3370
411x1458
411x1458
411x1458
836x1986
836x1986
AA Sensors
General Characteristics:
Parameter
Input Voltage Range
Operating Frequency
Operating Temperature Range
Bridge Electrical Offset
Signal Output at Max. Field
Nonlinearity
Hysteresis
TCR
TCOI
TCOV
Off Axis Characteristic
ESD Tolerance
Min
4
<1
DC
-50
-4
Typical
Max
4
24
>1
125
+4
Unit
Volts
MHz
°C
mV/V
mV/V
5
% (unipolar)
5
% (unipolar)
6
% / °C
6
% / °C
6
% / °C
60
2
4
+0.14
+0.03
-0.1
7
Cos β
400
V pin-to-pin HBM
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air.
2.
See the Appendix for package dimensions and tolerances.
3.
Sensors can be provided in die form by special request.
4.
GMR AA-Series sensors are pure ratiometric devices meaning that they will operate properly at extremely low supply
voltages. The output signal will be proportional to the supply voltage. Maximum voltage range is limited by the power
dissipation in the package and the maximum operating temperature of the sensor.
5.
Unipolar operation means exposure to magnetic fields of one polarity, e.g., 0 to 30 Gauss, or 2 to -50 Gauss, but not -20 to
+30 Gauss (bipolar operation). Bipolar operation will increase nonlinearity and hysteresis.
TCR is resistance change with temperature with no applied field. TCOI is the output change with temperature using a
6.
constant current source to power the sensor. TCOV is the output change with temperature using a constant voltage source
to power the sensor. See the graphs below.
7.
Beta (β) is any angle deviation from the sensitive axis.
AA002 Tem perature Performance, 5V Supply
0.35
0.3
0.3
0.25
0.25
0.2
0.2
Output Voltage (V)
Output Voltage (V)
AA002 Temperature Performance,
1m A Curre nt Supply
0.35
0.15
-40C
0.1
0.15
-40C
0.1
25C
25C
85C
85C
125C
0.05
0
-20
125C
0.05
0
-15
-10
-5
0
5
10
15
-20
20
-0.05
-15
-10
-5
0
5
-0.05
Applied Magnetic Field (Oe)
Applie d M agnetic Field (Oe)
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10
15
20
AAH Sensors
AAH Sensors
Features:
•
•
•
•
•
•
Extremely High Sensitivity to Applied Magnetic Fields
Wheatstone Bridge Analog Output
Temperature Tolerance to 150°C Continuous
Near-Zero Voltage Operation
DC to >1MHz Frequency Response
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
•
Low Voltage, High Temperature Applications
Low Field Sensing for Magnetic Media Detection
Earth’s Magnetic Field Detection
Current Sensing
Description:
The AAH-Series GMR sensors are manufactured with a high sensitivity GMR material, making them
ideally suited for any low magnetic field application. They are also extremely temperature tolerant, to
+150°C operating temperatures.
Pin-out
V+ (supply)
Functional Block Diagram
OUT+
pin 8,
V+(supply)
NVE
NVE
AAxxx
AAXXX-02
-02
Orientation
chamfer
Pin 1
shield
GMR
pin 5, OUT+
shield
OUT V- (ground)
Axis of Sensitivity
pin 1, OUT-
pin 4, V(ground)
Magnetic Characteristics:
Part
Number
AAH002-02
AAH004-00
Saturation
1
Field (Oe )
6
15
Linear
Range
1
(|Oe |)
Min
Max
0.6
3.0
1.5
7.5
Sensitivity
1
(mV/V-Oe )
Min
Max
11.0 18.0
3.2
4.8
3
Resistance
(Ohms)
Package
2K ±20%
2K ±20%
SOIC8
MSOP
2
- 16 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Die Size
(µm)
436x3370
411x1458
AAH Sensors
General Characteristics:
Parameter
Input Voltage Range
Operating Frequency
Operating Temperature Range
Bridge Electrical Offset
Signal Output at Max. Field
Nonlinearity
Hysteresis
TCR
TCOI
TCOV
Off Axis Characteristic
ESD Tolerance
Min
4
<1
DC
-50
-5
Typical
Max
4
±12
>1
150
+5
40
4
15
+0.11
+0.10
0.0
7
Cos β
400
Unit
Volts
MHz
°C
mV/V
mV/V
5
% (unipolar)
5
% (unipolar)
6
% / °C
6
% / °C
6
% / °C
V pin-to-pin HBM
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air.
2.
See the Appendix for package dimensions and tolerances.
3.
Sensors can be provided in die form by special request.
4.
GMR AAH-Series sensors are pure ratiometric devices meaning that they will operate properly at extremely low supply
voltages. The output signal will be proportional to the supply voltage. Maximum voltage range is limited by the power
dissipation in the package and the maximum operating temperature of the sensor.
5.
Unipolar operation means exposure to magnetic fields of one polarity, e.g. 0 to 30 Gauss, or -2 to -50 Gauss, but not -20 to
+30 Gauss (bipolar operation). Bipolar operation will increase nonlinearity and hysteresis.
TCR is resistance change with temperature with no applied field. TCOI is the output change with temperature using a
6.
constant current source to power the sensor. TCOV is the output change with temperature using a constant voltage source
to power the sensor.
7.
Beta (β) is any angle deviation from the sensitive axis.
AAH002 Temperature Performance, 5V Supply
0.4
0.4
0.35
0.35
0.3
0.3
0.25
0.25
Voltage Output (V)
Output Voltage (V)
AAH002 Temperature Performance,
2.28mA Current Source
0.2
0.15
-40C
0.1
0.2
0.15
-40C
0.1
25C
25C
85C
0.05
85C
0.05
125C
125C
0
-20
0
-20
-15
-10
-5
0
5
10
15
20
-15
-10
-5
0
5
-0.05
-0.05
Applied Magnetic Field (Oe)
Applied Magnetic Field (Oe)
- 17 www.nve.com phone: 952-829-9217 fax: 952-829-9189
10
15
20
AAL Sensors
AAL Sensors
Features:
•
•
•
•
•
•
•
Excellent Sensitivity to Applied Magnetic Fields
Wheatstone Bridge Analog Output
Temperature Tolerance to 150°C Continuous
Very Low Magnetic Hysteresis
Near-Zero Voltage Operation
DC to >1MHz Frequency Response
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
•
General Motion, Speed, and Position Sensing
Low Voltage, High Temperature Applications
Low Field Sensing for Magnetic Media Detection
Current Sensing
Description:
The AAL-Series GMR sensors are manufactured with a low hysteresis GMR material, for use in
magnetometer applications where minimum hysteresis is important. They are also extremely
temperature tolerant, to +150°C operating temperatures.
Pin-out
V+ (supply)
Functional Block Diagram
OUT+
pin 8,
V+(supply)
NVE
NVE
AAxxx
AAXXX-02
-02
Orientation
chamfer
Pin 1
shield
GMR
pin 5, OUT+
shield
OUT -
V- (ground)
pin 1, OUT-
pin 4, V(ground)
Axis of Sensitivity
Magnetic Characteristics:
Part
Number
AAL002-02
Saturation
1
Field (Oe )
15
Linear
Range
1
(|Oe |)
Min
Max
1.5
10.5
Sensitivity
1
(mV/V-Oe )
Min
Max
3.0
4.2
3
Resistance
(Ohms)
Package
5.5K ±20%
SOIC8
2
- 18 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Die Size
(µm)
436x3370
AAL Sensors
General Characteristics:
Parameter
Input Voltage Range
Operating Frequency
Operating Temperature Range
Bridge Electrical Offset
Signal Output at Max. Field
Nonlinearity
Hysteresis
TCR
TCOI
TCOV
Off Axis Characteristic
ESD Tolerance
Min
4
<1
DC
-50
-4
Typical
Max
4
±25
>1
150
+4
Unit
Volts
MHz
°C
mV/V
mV/V
5
% (unipolar)
5
% (unipolar)
6
% / °C
6
% / °C
6
% / °C
45
2
4
+0.11
-0.28
-0.40
7
Cos β
400
V pin-to-pin HBM
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air.
2.
See the Appendix for package dimensions and tolerances.
3.
Sensors can be provided in die form by special request.
4.
GMR AAL-Series sensors are pure ratiometric devices meaning that they will operate properly at extremely low supply
voltages. The output signal will be proportional to the supply voltage. Maximum voltage range is limited by the power
dissipation in the package and the maximum operating temperature of the sensor.
5.
Unipolar operation means exposure to magnetic fields of one polarity, e.g. 0 to 30 Gauss, or -2 to -50 Gauss, but not -20 to
+30 Gauss (bipolar operation). Bipolar operation will increase nonlinearity and hysteresis.
TCR is resistance change with temperature with no applied field. TCOI is the output change with temperature using a
6.
constant current source to power the sensor. TCOV is the output change with temperature using a constant voltage source
to power the sensor.
7.
Beta (β) is any deviation angle from the sensitive axis.
AAL002 Temperature Performance,
1mA Current Supply
AAL002 Temperature Performance, 5V Supply
0.35
0.35
0.3
-40C
25C
85C
125C
0.3
0.25
Output Voltage (V)
Output Voltage (V)
0.25
0.2
0.15
0.1
-40C
0.2
0.15
0.1
25C
0.05
85C
0.05
125C
0
0
-30
-20
-10
0
10
20
-30
30
-20
-10
0
10
-0.05
-0.05
Applie d M ag ne tic F ie ld (O e )
Applied Magnetic Field (Oe)
- 19 www.nve.com phone: 952-829-9217 fax: 952-829-9189
20
30
AAV Sensors
AAV Sensors
Features:
•
•
•
•
•
•
•
Operates in Magnetic Saturation, 30 to 200 Gauss
Half-Bridge or Individual Resistor Configurations
Sine and Cosine Outputs Available
Utilizes Spin Valve GMR Material
Precise Detection of Magnetic Field
Ultra-Small PLLP Package
Cannot Be Damaged by Large External Magnetic Fields
Description:
The AAV001-11 and AAV002-11 are arrays of four GMR resistors rotated at 90-degree intervals in
the package. The AAV001-11 features independent resistors that can be wired together to form two
half-bridges, or used as independent resistors. The AAV002-11 has the bridge connections made
internally to the package. For either part, the output can be configured to represent the sine and cosine
function of the magnetic field being applied to the sensor. Each resistor is 1.5 kΩ nominal resistance
and output of each half-bridge is ratiometric with the power supply voltage. The part features NVE’s
PLLP6 housing, which is a 3.0 mm x 3.0 mm x 0.9 mm thick surface mount package.
Operation:
The sensor elements contain two magnetic layers: a pinned, or fixed-direction layer, and a movable or
free layer. The diagram below illustrates the configuration with arrows representing the two layers:
r
ye
La
ee
Fr
Ap
p
(3 lied
0t M
o 2 ag
00 net
Ga ic F
us iel
s) d
Pinned Layer
Angle Between Pinned
and Free Layers
Determines Electrical
Resistance of Sensor
Free Layer Aligns
with the Applied
Magnetic Field
- 20 www.nve.com phone: 952-829-9217 fax: 952-829-9189
AAV Sensors
The end user must apply a saturating magnetic field (30 to 200 Oersteds) in the plane of the sensor in
order for the sensor to operate. The movable layer will align with the applied magnetic field. As the
applied field changes direction the angle between the movable layer and the pinned layer changes,
resulting in a change of resistance in the device. A graph of the device resistance vs. the angle between
the pinned layer and the movable layer is shown below:
Resistance (Ohms)
Resistance Change of Spin Valve
Sensor Element
1520
1510
1500
1490
1480
1470
1460
1450
1440
1430
1420
0
90
180
270
360
Angle Between Pinned and Movable Layers
Four individual sensor resistors are supplied in the package, each with the pinned layer rotated 90º with
respect to that of the previous sensor. These resistors can be connected in two half-bridge
configurations to provide a sine and cosine output or monitored individually to provide an absolute
indication of the angle between the pinned layer and the movable layer.
- 21 www.nve.com phone: 952-829-9217 fax: 952-829-9189
AAV Sensors
A drawing showing the ICs position in the package is given below. On each IC there is an arrow
indicating the direction of the pinned layer.
Functional Block Diagram, Marking, and Pinout, AAV001-11:
Cosine Output
BBP
R3
R2
R3 (Cosine)
R2 (Sine)
VCC
GND
R1 (Sine)
R4 (Cosine)
R1
R4
- 22 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Sine Output
AAV Sensors
Functional Block Diagram, Marking, and Pinout, AAV002-11:
BBQ
VCC
R3 (Cosine)
Cosine Output
R2 (Sine)
Cos
Sin
R4 (Cosine)
Sine Output
R1 (Sine)
GND
Specifications:
Parameter
Nominal Resistance of Each Resistor
Maximum Resistance Decrease with Field
Change
Required Strength of Applied Magnetic Field
Measurement Error
Supply Voltage
Offset Voltage
Temperature Range of Operation
Storage Temperature
Temperature Coefficient of Resistance
3
TCOV
3
TCOI
Test
Condition
25°C
Operating at
25°C
Operating
Operating
Operating
Operating at
25°C
Operating
Min
1200
4.5%
Typ
1500
5.2%
Max
1800
7%
Units
Ohms
-10
200
2
12
10
Oersted
Degrees
Volts
mV/V
-40
-40
150
170
°C
°C
%/°C
%/°C
%/°C
30
Operating
Operating
Operating
+0.3
-0.24
-0.16
2
Notes:
1.
Large Magnetic Fields WILL NOT cause damage to NVE GMR Sensors.
2.
1 Oe (Oersted) = 1 Gauss in air = 0.1 mTesla = 79.8 Amps/meter.
3.
TCOV is the percent change in output signal over temperature with a constant voltage source powering the part and TCOI
is the percent change in output over temperature with a constant current source.
- 23 www.nve.com phone: 952-829-9217 fax: 952-829-9189
AB Sensors
AB Sensors
Features:
•
•
•
•
•
•
•
Excellent Sensitivity to Applied Magnetic Fields
Wheatstone Bridge Analog Output
Temperature Tolerance to 125°C Continuous
Wide Linear Range of Operation
Near-Zero Voltage Operation
DC to >1MHz Frequency Response
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
General Differential Field Sensing
Gear Tooth and Encoder Speed and Position Sensing
Low Power, Low Voltage Applications
Description:
The AB-Series GMR sensors are general-purpose gradiometers for use in a wide variety of
applications. Two pairs of unshielded GMR sensor elements provide for directional sensing of small
gradients in large and small magnetic fields. The ability to detect only magnetic gradients allows low
sensitivity to external sources of uniform magnetic field allowing these sensors to work successfully in
high magnetic noise environments such as near electric motors or current carrying wires.
Functional Block diagram
Pinout
V+ (supply)
OUT B
pin 8, V+(supply)
GMR
NVE
ABxxx-02
X
Y
X
pin 5, OUT B
Y
X
Y
pin 1, OUT A
Pin 1
OUT A
pin 4, V(ground)
V- (ground)
Axis of Sensitivity
Magnetic Characteristics:
Part
Number
AB001-02
AB001-00
Saturation
1
Field (Oe )
250
250
Linear
Range
1
(|Oe |)
Min
Max
10
175
10
175
Resistor
Sensitivity
1
(%R / Oe )
Min
Max
0.02 0.03
0.02 0.03
3
Resistance
(Ohms)
Package
2.5K ±20%
2.5K ±20%
SOIC8
MSOP8
2
- 24 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Die Size
(µm)
651x1231
651x1231
AB Sensors
General Characteristics:
Parameter
Input Voltage Range
Operating Frequency
Operating Temperature Range
Bridge Electrical Offset
Signal Output at Max. Field
Nonlinearity
Hysteresis
TCR
TCOI
TCOV
Off Axis Characteristic
ESD Tolerance
Min
4
<1
DC
-50
-4
Typical
Max
4
±12.5
>1
125
+4
120
2
4
+0.14
+0.03
-0.1
7
Cos β
400
Unit
Volts
MHz
°C
mV/V
mV/V
5
% (unipolar)
5
% (unipolar)
6
% / °C
6
% / °C
6
% / °C
V pin-to-pin HBM
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air.
2.
See the Appendix for package dimensions and tolerances.
3.
Sensors can be provided in die form by special request.
4.
GMR AB-Series sensors are pure ratiometric devices, meaning that they will operate properly at extremely low supply
voltages. The output signal will be proportional to the supply voltage. Maximum voltage range is limited by the power
dissipation in the package and the maximum operating temperature of the sensor.
5.
Unipolar operation means exposure to magnetic fields of one polarity, e.g., 0 to 30 Gauss, or -2 to -50 Gauss, but not -20
to +30 Gauss (bipolar operation). Bipolar operation will increase nonlinearity and hysteresis.
6.
TCR is resistance change with temperature with no applied field. TCOI is the output change with temperature using a
constant current source to power the sensor. TCOV is the output change with temperature using a constant voltage source
to power the sensor.
Beta (β) is any angle deviation from the sensitive axis.
Typical Gradiometer Transfer Function
50
Differential Voltage Out of Sensor (mV)
7.
40
30
20
Increasing field
on X resistors
10
0
-400Increasing -200
field
on Y resistors
-10
0
200
-20
400
The Figure at left is a
simulated output from an
NVE Gradiometer. The
output / gradient
correlation shown
assumes one pair of
resistors is held at zero
field. Note the bipolar
output.
-30
-40
-50
Magnetic Field Applied to Resistors
- 25 www.nve.com phone: 952-829-9217 fax: 952-829-9189
ABH Sensors
ABH Sensors
Features:
•
•
•
•
•
•
•
Extremely High Sensitivity to Applied Magnetic Fields
Wheatstone Bridge Analog Output
Temperature Tolerance to 150°C Continuous
Wide Linear Range of Operation
Near-Zero Voltage Operation
DC to >1MHz Frequency Response
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
General Differential Field Sensing
Gear Tooth and Encoder Speed and Position Sensing
Low Voltage, High Temperature Applications
Description:
The ABH-Series GMR sensors are low field, high temperature gradiometers for use in a wide variety
of applications. Two pairs of unshielded GMR sensor elements provide for directional sensing of small
gradients in large and small magnetic fields. The ability to detect only magnetic gradients allows low
sensitivity to external sources of uniform magnetic field allowing these sensors to work successfully in
high magnetic noise environments such as near electric motors or current carrying wires.
Functional Block diagram
Pinout
OUT B
V+ (supply)
pin 8, V+(supply)
GMR
NVE
ABxxx-02
X
Y
X
pin 5, OUT B
Y
X
Y
pin 1, OUT A
Pin 1
OUT A
pin 4, V(ground)
V- (ground)
Axis of Sensitivity
Magnetic Characteristics:
Part
Number
ABH001-00
Saturation
1
Field (Oe )
70
Linear
Range
1
(|Oe |)
Min
Max
5
40
Resistor
Sensitivity
1
(%R / Oe )
Min
Max
0.06 0.12
3
Resistance
(Ohms)
Package
1.2K ±20%
MSOP8
2
- 26 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Die Size
(µm)
651x1231
ABH Sensors
General Characteristics:
Parameter
Input Voltage Range
Operating Frequency
Operating Temperature Range
Bridge Electrical Offset
Signal Output at Max. Field
Nonlinearity
Hysteresis
TCR
TCOI
TCOV
Off Axis Characteristic
ESD Tolerance
Min
4
<1
DC
-50
-4
Typical
Max
4
±6
>1
150
+4
80
4
15
+0.11
+0.10
0.0
7
Cos β
400
Unit
Volts
MHz
°C
mV/V
mV/V
5
% (unipolar)
5
% (unipolar)
6
% / °C
6
% / °C
6
% / °C
V pin-to-pin HBM
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air.
2.
See the Appendix for package dimensions and tolerances.
3.
Sensors can be provided in die form by special request.
4.
GMR AB-Series sensors are pure ratiometric devices meaning that they will operate properly at extremely low supply
voltages. The output signal will be proportional to the supply voltage. Maximum voltage range is limited by the power
dissipation in the package and the maximum operating temperature of the sensor.
5.
Unipolar operation means exposure to magnetic fields of one polarity, e.g., 0 to 30 Gauss, or -2 to -50 Gauss, but not -20 to
+30 Gauss (bipolar operation). Bipolar operation will increase nonlinearity and hysteresis.
6.
TCR is resistance change with temperature with no applied field. TCOI is the output change with temperature, using a
constant current source to run the sensor. TCOV is the output change with temperature, using a constant voltage source to
run the sensor.
Beta (β) is any angle deviation from the sensitive axis.
Typical Gradiometer Transfer Function
50
Differential Voltage Out of Sensor (mV)
7.
40
30
20
Increasing field
on X resistors
10
0
-400Increasing -200
field
on Y resistors
-10
0
200
-20
400
The Figure at left is a
simulated output from an
NVE Gradiometer. The
output / gradient
correlation shown
assumes one pair of
resistors is held at zero
field. Note the bipolar
output.
-30
-40
-50
Magnetic Field Applied to Resistors
- 27 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
GMR Switch Precision Digital Sensors
When GMR sensor elements are combined with digital on-board signal processing electronics the
result is the GMR Switch. The GMR Switch offers unmatched precision and flexibility in magnetic
field sensing.
The GMR Switch will accurately and reliably sense magnetic fields with less error than any other
magnetic sensor on the market today. In addition, there is little shift in the magnetic field operate point
of the GMR Switch over voltage and temperature extremes. This gives NVE’s customer the ability to
make a high precision, high tolerance magnetic sensing assembly.
The GMR switch can operate over a wide range of magnetic fields and is the most precise magnetic
sensor on the market. It is the clear choice when a digital output signal is required of a magnetic
sensor.
Operate Point Error Band for Typical Magnetic Sensors
(4.5V to 30V, -40˚C to +125˚C)
200
Magnetic
Operate Point
(Gauss)
150
Allegro 3141LLT
(Hall Effect)
Honeywell SS441A
(Hall Effect)
The GMR Switch Holds Tighter
Operate Point Specifications
Than Any Competing Product!
NVE AD023-00
(GMR)
NVE AD022-00
(GMR)
Honeywell 2SSP
(AMR)
50
- 28 www.nve.com phone: 952-829-9217 fax: 952-829-9189
NVE AD021-00
(GMR)
GMR Switch Precision Digital Sensors
Quick Reference: GMR Switch Digital Sensors
The following table lists some of NVE’s most popular GMR Switch products and their key
specifications:
Part Number
Typical
Typical
Magnetic
Magnetic
Operate
Release
Point
Point
1
1
Maximum
Output
(Oe )
(Oe )
Type
NVE AD004-02
20
10
NVE AD005-02
40
25
NVE AD021-00
20
NVE AD022-00
40
NVE AD024-00
NVE AD124-00
2
Operation
Temperature (°C)
Package Type
Sink
125
SOIC8
Sink
125
SOIC8
10
Sink
125
MSOP8
25
Sink
125
MSOP8
28
14
Sink
125
MSOP8
28
14
Source
125
MSOP8
125
MSOP8
125
MSOP8
150
MSOP8
3
Sink +
NVE AD621-00
20
10
Source+
VREG
NVE AD824-00
28
14
NVE ADH025-00
11
5
2 Sinks +
SCP
Sink
Notes:
1.
1 Oersted (Oe) = 1 Gauss in air
2.
Output Types:
Sink = Up to 20 mA current sink
Source = Up to 20 mA current source
SCP = Short Circuit Protection available for external transistor
3.
See Appendix for package dimensions
Note on Availability of Products
NVE keeps about 25 of the most popular types of GMR Switch products in stock at our manufacturing
facility. However, because there are over 100 different varieties of GMR Switch parts, some part
numbers may require a six to eight week lead time before production quantities are available. Please
contact NVE for further information.
- 29 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
GMR Switch Product Selection Guide
NVE’s GMR Switch is available in a wide range of packaging, output type, and magnetic trigger field
varieties. The purpose of this selection guide is to explain the different output and packaging options,
as well as to provide information on how to specify the correct part number when ordering.
All NVE GMR Switch product part numbers follow the same general form. As shown below, the first
“x” in the part number specifies output type and available voltage regulator output, the next two x’s
specify trigger field and direction of sensitivity, and the last pair specify the package type. The
following sections define these variations in detail.
Output Type and Available Regulator
The first numeric digit of the part number NVE ADxxx-xx specifies the output type, and the
availability of a regulated voltage supply on a separate pin. The following four output types are
available:
20 mA Current Sink
20 mA Current Source
Separate 20 mA Sink and Source
Two Separate 20 mA Sinks
All outputs turn ON when the magnetic field is applied. An output that turns OFF when the magnetic
field is applied is available as a custom product; please consult NVE.
Some of NVE’s GMR Switches also feature a regulated supply voltage available external to the part on
a separate pin. This regulator provides a 5.8V reference capable of supplying up to 3 mA of drive
current. This regulated output may be used to run an LED or other low power device.
In addition to these options, NVE recently introduced a GMR Switch that has provisions for shutting
down an external power transistor in case a short circuit is detected. This is useful in applications
where the finished sensor assembly must be “bulletproof,” or immune to improper connection.
- 30 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
The following table defines the first digit in the NVE AD part number:
NVE AD x xx-xx
Number
0
1
2
3
4
5
6
7
8
9
Output Configuration
20mA Current Sink
20 mA Current Source
Separate 20mA Current Sink and 20mA Current Source
Two Separate 20mA Current Sinks
20mA Current Sink + Regulated Output Voltage
20 mA Current Source + Regulated Output Voltage
Separate 20mA Current Sink and 20mA Current Source + Regulated
Output Voltage
Two Separate 20mA Current Sinks + Regulated Output Voltage
Two Separate 20mA Current Sinks + Regulated Output Voltage + Short
Circuit Detection and Shut-Off
Separate 20mA Current Sink and 20mA Current Source + Regulated
Output Voltage + Short Circuit Detection and Shut-Off
Trigger Field, Direction of Sensitivity, Low Voltage Operation
The second and third numeric digits of the part number NVE ADxxx-xx specify the magnetic trigger
field and direction of sensitivity of the part. Five different magnetic trigger fields are available for the
GMR Switch:
10 Gauss (10 Oe, 1.0 mT, 0.8 kA/m)
20 Gauss (20 Oe, 2.0 mT, 1.6 kA/m)
28 Gauss (28 Oe, 2.8 mT, 2.23 kA/m)
40 Gauss (40 Oe, 4.0 mT, 3.2 kA/m)
80 Gauss (80 Oe, 8.0 mT, 6.4 kA/m)
Other magnetic trigger field levels ranging up to 250 Gauss are available on a custom basis; please
contact NVE.
In addition to defining the magnetic operate point; these two digits are used to define the direction of
sensitivity and optional low voltage operation. The GMR Switch can be ordered in Standard Axis or
Cross Axis directions of sensitivity. For definitions please see NVE AD Series Sensitivity Direction
and Pin Configuration later in this section.
NVE also makes a GMR Switch with the on-chip voltage regulator bypassed. This limits the voltage
range of the part, but allows it to operate at voltages as low as 3.0V.
- 31 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
The following table defines the second and third digits in the NVE AD part number:
NVE AD x xx-xx
Number
04
05
06
20
21
22
23
24
25
81
82
83
84
Configuration
20 Gauss OP, Standard Direction of Sensitivity
40 Gauss OP, Standard Direction of Sensitivity
80 Gauss OP, Standard Direction of Sensitivity
28 Gauss OP, Standard Direction of Sensitivity
20 Gauss OP, Cross Axis Direction of Sensitivity
40 Gauss OP, Cross Axis Direction of Sensitivity
80 Gauss OP, Cross Axis Direction of Sensitivity
28 Gauss OP, Cross Axis Direction of Sensitivity
10 Gauss OP, Cross Axis Direction of Sensitivity
(ADH Series Only; see page 38)
20 Gauss OP, Cross Axis Direction of Sensitivity, Low Volt
40 Gauss OP, Cross Axis Direction of Sensitivity, Low Volt
80 Gauss OP, Cross Axis Direction of Sensitivity, Low Volt
28 Gauss OP, Cross Axis Direction of Sensitivity, Low Volt
Note: For parts that operate at 10 Gauss, see the following section describing the NVE ADH-Series sensors.
NVE AD-Series Sensitivity Direction and Pin Configuration
Pin configuration for the NVE AD-Series GMR Switches is given in the following diagrams. In
addition, most GMR Switch parts are available with a choice of two directions of sensitivity.
“Standard” direction of sensitivity is defined as the direction parallel to the edge of the package
containing the pins. “Cross-Axis” direction of sensitivity is defined as the direction perpendicular to
the edge of the package containing the pins. Pin configuration and sensitivity direction is defined in the
drawings below:
NVE AD0xx-xx through NVE AD7xx-xx, NVE ADH0xx-xx:
Source
Sink(2)
Standard Axis
N/C
Ground
VCC
VCC
N/C*
Source
Sink(1)
N/C*
Cross Axis
Vreg
Vreg
Sink(2)
Sink(1)
Ground
N/C
Note: In the case of a Standard Axis Part with the Vreg pin option, Sink(1) will appear at the pin labelled N/C*
NVE AD8xx-xx through NVE AD9xx-xx:
Cap2
Cap
VCC
Cap2
VCC
AD9xx-xx
AD8xx-xx
ShortH
Cap
ShortH
Cross Axis
Cross Axis
Sink(2)
Sink(1)
Sink(2)
Sink(1)
Ground
Vreg
Ground
Vreg
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GMR Switch Precision Digital Sensors
Package Type
NVE GMR Switches are available in three different packages: an SOIC 8-pin package, an MSOP 8-pin
small outline package, and a TDFN 6 pin ultra-miniature package. Package drawings are shown in the
Appendix.
The following table defines the last two digits in the NVE AD part number:
Number
00
02
1
10
1
Package Type
MSOP8
SOIC8
TDFN6
At this time, the TDFN6 package is only available in AD0xx-10 configuration.
In addition to these three package types, NVE offers a custom version of the MSOP8 package for the
NVE AD024-00 part. In this version, the BD012-00, all three connections are made on one side of the
package, and the pins on the other side of the package are clipped off flush with the body of the
package. This allows the user to position the sensing element as close to the edge of a circuit board or
assembly as possible. A pinout of this package is shown below:
VCC
BD012-00
N/C*
Cross Axis
Out
Ground
The maximum length of the clipped leads is 0.30 mm leading to an overall package length of 4.25 mm,
as compared to 4.90 mm for the normal MSOP8 package. This part is available in tape and reel format
only.
Other versions of the GMR Switch may be available in this package configuration on a special order
basis. Please contact NVE for further information.
- 33 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
Characteristics Over Voltage and Temperature
Typical Operate Points (OP) and Release Points (RP)
AD004 and AD005
Applied Field
(Oersteds)
50
Ambient Temperature = 25C
40
AD005 OP
30
AD005 RP
20
AD004 OP
AD004 RP
10
0
5
10
15
20
25
30
Supply Voltage
Operate Point (OP) and Release Point (RP) Variation
Over Temperature
Applied Field (Oe)
50
40
AD005 OP
30
AD005 RP
20
AD004 OP
AD004 RP
10
0
-40
0
40
80
120
Temperature (C)
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GMR Switch Precision Digital Sensors
Temperature (C)
Operating Temperature Derating Curves for SOIC8,
MSOP8, and TDFN6 Packages in Free Air
130
120
110
100
90
80
SOIC8
MSOP8 and
TDFN6
5
10
15
20
25
30
Supply Voltage (V)
Output Current Derating Curve
Maximum Output
Current (mA)
25
20
15
10
4.5
6
7.5
9
Supply Voltage (V)
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10.5
GMR Switch Precision Digital Sensors
AD0xx-xx to AD7xx-xx
Features:
•
•
•
•
•
•
•
Precision Magnetic Operate Point
Excellent Temperature and Voltage Performance
Digital Outputs
Frequency Response 0 to 250kHz
Optional Voltage Regulator Output
Optional Low Voltage Version
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
General Digital Position Sensing
Pneumatic Cylinder Position Sensing
Speed Sensing
Description:
The NVE AD0xx-xx to AD7xx-xx GMR Switches are digital output magnetometers that offers
precision operate points over all temperature and input voltage conditions. They are available with
magnetic trigger fields from 20 to 80 Gauss and four different output configurations, making them an
extremely flexible and user-friendly design.
Functional Block Diagram (NVE AD0xx-xx to NVE AD7xx-xx, (Except NVE AD08x-xx):
Voltage
Regulator
(5.8V)
Current Sinking
Output
4.5V to 30V
GMR
Bridge
Comparator
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GMR Switch Precision Digital Sensors
Functional Block Diagram (NVE AD08x-xx):
3.0V to 6.0V
Current Sinking
Output
GMR
Bridge
Comparator
Output Characteristic as a Function of Magnetic
Field, for AD024-00 GMR Switch
Output Current, mA
(10V Supply, 1K Load Resistor)
12
10
ON
OFF
8
OFF
ON
6
4
2
0
-40
-20
0
20
40
Applied Ma gnetic Fie ld (Oe)
Magnetic Characteristics:
Typical Operate
Point
20
28
40
80
Minimum
Operate Point
15
21
30
60
Maximum Operate
Point
25
34
50
100
Minimum
1,2
Differential
5
5
5
5
Maximum
1,2
Differential
14
20
25
35
Note: All Values in Oersteds (Oe); 1 Oe = 1 Gauss in Air
- 37 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
Electrical Specifications
(NVE AD0xx-xx to NVE AD7xx-xx, except NVE AD08x-xx):
Parameter
4
Supply Voltage
Supply Current, Single Output
3
Current Sinking Output
3
Current Sourcing Output
Output Leakage Current
Sinking Output Saturation Voltage
Sourcing Output Saturation Voltage
6
Regulated Output Voltage
Regulated Output Current
Symbol
VCC
ICC
IO
IO
ILEAK
VOL
VOH
VREG
IREG
Min
4.5
2.5
0
0
3.5
Max
30
4.5
20
20
10
0.4
VCC-2.5
6.2
3.0
Units
V
mA
3
mA
3
mA
µA
V
V
V
mA
Test Condition
Operating
Output Off, VCC=12V
Operating
Operating
Output Off, VCC=12V
Output On, IOL=20mA
Output On, IOL=20mA
Operating
Operating
Max
6.0
1.2
2.2
20
10
0.4
Units
V
mA
mA
3
mA
µA
V
Test Condition
Operating
Output Off, VCC=3V
Output Off, VCC=6V
Operating
Output Off, VCC=5V
Output On, IOL=20mA
Electrical Specifications (NVE AD08x-xx):
Parameter
Supply Voltage
Supply Current
Supply Current
3
Current Sinking Output
Output Leakage Current
Sinking Output Saturation Voltage
Symbol
VCC
ICC
ICC
IO
ILEAK
VOL
Min
3.0
0.7
1.7
0
Absolute Maximum Ratings
(NVE AD0xx-xx to NVE AD7xx-xx, except NVE AD08x-xx):
Parameter
Supply Voltage
Reverse Battery Voltage
Current Sinking Output Off Voltage
Current Sourcing Output Off Voltage
Current Sinking Reverse Output Voltage
Current Sourcing Reverse Output Voltage
Output Current
4
Operating Temperature Range
Storage Temperature Range
5
Magnetic Field
Symbol
VCC
VRBP
I0
TA
TS
H
Min
-40
-65
Max
33
-33
33
0
-0.5
-0.5
24
125
150
None
Units
V
V
V
V
V
V
mA
°C
°C
Oe
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GMR Switch Precision Digital Sensors
Absolute Maximum Ratings (NVE AD08x-xx):
Parameter
Supply Voltage
Reverse Battery Voltage
Current Sinking Output Off Voltage
Current Sinking Reverse Output Voltage
Output Current
4
Operating Temperature Range
Storage Temperature Range
5
Magnetic Field
Symbol
VCC
VRBP
I0
TA
TS
H
Min
-40
-65
Max
7
-0.5
33
-0.5
24
125
150
None
Units
V
V
V
V
mA
°C
°C
Oe
Notes:
1.
Differential = Operate Point - Release Point
2.
Minimum Release Point for AD0xx-xx to AD7xx-xx, except AD08x-xx, = 5 Oe. Minimum Release Point for
3.
Output current must be limited by a series resistor. Exceeding absolute maximum continuous output current ratings will
AD08x-xx = 3.5 Oe.
result in damage to the part. See the figure in the GMR Switch Product Selection Guide for an output current derating
curve.
4.
Thermal power dissipation for the packages used by NVE is 240°C/Watt for the SOIC8 package, and 320°C/Watt for the
MSOP8 and TDFN6 packages. See the Figure on Ambient Temperature vs. Supply Voltage for derating information. Heat
sinking the parts by attaching them to a PCB improves temperature performance.
5.
There is no maximum magnetic field that will cause damage to the device.
6.
If VCC > 6.6V, VREG = 5.8V. If VCC < 6.6V, VREG= VCC - 0.9V.
- 39 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
AD8xx-xx to AD9xx-xx
Features:
•
•
•
•
•
•
Short Circuit Detection and Shutoff of External Power Transistor
Precision Magnetic Operate Point
Excellent Temperature and Voltage Performance
Digital Outputs
Frequency Response 0 to 250kHz
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
General Digital Position Sensing
Pneumatic Cylinder Position Sensing
Speed Sensing
Description:
NVE AD8xx and AD9xx GMR Switches are designed specifically for use with an external high
current output transistor in industrial control environments. These parts provide the same precise
magnetic performance NVE’s GMR Switch is known for with the additional functionality of short
circuit protection (SCP) for the output stage of the circuit. The protection circuit is designed to shut off
the output stage when a short circuit condition exists. After a user-specified time interval, the circuit
turns back on. If the short circuit condition still exists, the output stage is again shut off and the cycle
repeats. This sensor, along with external reverse battery protection and overvoltage protection, results
in a “bulletproof” sensor assembly. A functional block diagram of this sensor is shown below:
VDD
Vreg
GMR
Bridge
Sink1
Comparator
Comparator
ShortH
Sink2
Cap2
SCP Turn
On Delay
Cap
Off State
Timer
Ground
These digital sensors with SCP are available for use with current sinking or current sourcing outputs,
in a range of magnetic field operate points. They are provided in an MSOP8 package with the crossaxis direction of sensitivity. An LED driver to indicate the presence of the magnetic field is also
standard on these products. An SOIC8 package and standard axis sensitivity are available on a special
order basis.
- 40 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
Typical Circuit Configuration:
VDD
RBIAS1
Pin 1
Cap2
VDD
Cap
RSHORT
ShortH
AD821-00
Sink2
Sink1
Ground
Vreg
RBIAS2
Output
RLED
t2 Cap
t1 Cap
VDD
Pin 1
Cap2
VDD
Cap
ShortL
AD921-00
Source
Sink1
Ground
Vreg
Output
t2 Cap
t1 Cap
RLED
RBIAS2
RBIAS1
RSHORT
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GMR Switch Precision Digital Sensors
Output Transistor Current in Short Circuit mode:
Current (mA)
Output Transistor Current in Short Circuit
300
200
100
t
t1
2
Time
Notes:
1.
The t2 Capacitor is used to delay the startup of the SCP circuitry in order to avoid triggering the SCP circuitry on normal
2.
The t1 Capacitor is used to set the “Off” time of the SCP circuitry; see t1 on the graph above. Typical value is 16V, 0.01µF,
3.
The voltage across RSHORT is monitored by the IC. If this voltage exceeds 145 mV (typical), the SCP circuitry is activated.
4.
RBIAS1 and RBIAS2 are used to bias the output transistor. Typical values for RBIAS1 and RBIAS2 are 16kΩ and 3kΩ,
startup transients: see t2 on the graph above. Typical value is 16V, 0.001µF, for a 35µs delay.
for a 15 ms Off time.
Typical value of RSHORT is 0.47Ω, 1/16 watt. This will result in SCP circuitry turning on at about 300 mA of output current.
respectively, to supply 1 mA drive to the output transistor.
5.
RLED is sized for whatever LED current is required by the user (maximum of 3 mA.)
Magnetic Characteristics:
Typical Operate
Point
20
28
40
80
Minimum
Operate Point
15
21
30
60
Maximum
Operate Point
25
34
50
100
Minimum
1,2
Differential
5
5
5
5
Maximum
1,2
Differential
14
20
25
35
Note: All Values in Oersteds (Oe); 1 Oe = 1 Gauss in Air
- 42 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
Electrical Specifications:
Parameter
4
Supply Voltage
Supply Current
3
Current Sinking Output
3
Current Sourcing Output
Output Leakage Current
Sinking Output Saturation Voltage
Sourcing Output Saturation Voltage
6
Regulated Output Voltage
Regulated Output Current
Short High Voltage
Short Low Voltage
Symbol
VCC
ICC
IO
IO
ILEAK
VOL
VOH
VREG
IREG
ShortH
ShortL
Min
4.5
1.75
0
0
3.5
0.12
0.12
Max
30
3.5
2.0
2.0
10
0.4
VCC-2.0
6.0
3.0
0.17
0.17
Units
V
mA
3
mA
3
mA
µA
V
V
V
mA
V
V
Test Condition
Operating
Output Off, VCC=12V
Operating
Operating
Output Off, VCC=12V
Output On, IOL=2mA
Output On, IOL=2mA
Operating
Operating
Output On
Output On
Absolute Maximum Ratings:
Parameter
Supply Voltage
Reverse Battery Voltage
Current Sinking Output Off Voltage
Current Sourcing Output Off Voltage
Current Sinking Reverse Output Voltage
Current Sourcing Reverse Output Voltage
Output Current
4
Operating Temperature Range
Storage Temperature Range
5
Magnetic Field
Symbol
VCC
VRBP
I0
TA
TS
H
Min
-40
-65
Max
33
-0.5
33
0
-0.5
-0.5
5
125
135
None
Units
V
V
V
V
V
V
mA
°C
°C
Oe
Notes:
1.
Differential = Operate Point - Release Point
2.
Minimum Release Point for AD8xx-xx to AD9xx-xx = 5 Oe.
3.
Output current must be limited by a series resistor. Exceeding absolute maximum continuous output current ratings will
4.
Thermal power dissipation for the packages used by NVE is 240°C/Watt for the SOIC8 package, and 320°C/Watt for the
result in damage to the part.
MSOP8 and TDFN6 packages. See the Figure on Ambient Temperature vs. Supply Voltage for derating information. Heat
sinking the parts by attaching them to a PCB improves temperature performance.
5.
There is no maximum magnetic field that will cause damage to the device.
6.
If VCC > 6.6V, VREG = 5.8V. If VCC < 6.6V, VREG= VCC - 0.9V.
- 43 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GMR Switch Precision Digital Sensors
ADH0xx-xx
Features:
•
•
•
•
•
Precision Low Field Magnetic Operate Point
Excellent Temperature and Voltage Performance
Digital Output
Frequency Response 0 to 250kHz
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
Low Field Digital Position Sensing
Pneumatic Cylinder Position Sensing
Speed Sensing
Description:
The NVE ADH0xx Series GMR Switch uses NVE’s high sensitivity, high temperature GMR material
to provide a very low magnetic field operate point. It offers the same precision operate points over all
temperature and input voltage conditions as our other GMR Switch products. It is available in standard
form as the NVE ADH025-00 with a magnetic trigger field of 10 Gauss, a current sinking output, and a
cross axis configuration. Custom versions with trigger fields ranging from 6 to 40 Gauss, and different
output options and sensitivity directions could be manufactured for specific customer requirements;
please contact NVE for details.
Note: Functional Block Diagram for the NVE ADH0xx-xx Series sensors is the same as for the NVE
AD0xx-xx sensors.
Output Current, mA
(10V Supply, 1K Load Resistor)
Output Characteristic as a Function of Magnetic
Field, ADH025-00
12
10
8
ON
OFF
OFF
ON
6
4
2
0
-14 -12 -10
-8
-6
-4
-2
0
2
4
6
8
10
12 14
Applie d Ma gnetic Fie ld (Oe )
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GMR Switch Precision Digital Sensors
Magnetic Characteristics, NVE ADH025-00:
Typical
Operate Point
10 Oe
Minimum
Operate Point
8 Oe
Maximum
Operate Point
12 Oe
Minimum
1
Differential
3.5 Oe
Maximum
1
Differential
10 Oe
Test
Conditions
VCC=12V, 25°C
Electrical Specifications, NVE ADH0xx-xx:
Parameter
4
Supply Voltage
Supply Current, Single Output
3
Current Sinking Output
Output Leakage Current
Sinking Output Saturation Voltage
Symbol
VCC
ICC
IO
ILEAK
VOL
Min
4.5
3.0
0
Max
30
6.0
20
10
0.4
Units
V
mA
3
mA
µA
V
Test Condition
Operating
Output Off, VCC=12V
Operating
Output Off, VCC=12V
Output On, IOL=20mA
Absolute Maximum Ratings:
Parameter
Supply Voltage
Reverse Battery Voltage
Current Sinking Output Off Voltage
Current Sourcing Output Off Voltage
Current Sinking Reverse Output Voltage
Current Sourcing Reverse Output Voltage
Output Current
4
Operating Temperature Range
Storage Temperature Range
5
Magnetic Field
Symbol
VCC
VRBP
I0
TA
TS
H
Min
-40
-65
Max
33
-33
33
0
-0.5
-0.5
24
125
150
None
Units
V
V
V
V
V
V
mA
°C
°C
Oe
Notes:
1.
Differential = Operate Point - Release Point
2.
Minimum Release Point for ADH0xx-xx = 2.0 Oe.
3.
Output current must be limited by a series resistor. Exceeding absolute maximum continuous output current ratings will
result in damage to the part. See the figure in the GMR Switch Product Selection Guide for an output current derating
curve.
4.
Thermal power dissipation for the packages used by NVE is 240°C/Watt for the SOIC8 package, and 320°C/Watt for the
MSOP8 and TDFN6 packages. See the Figure on Ambient Temperature vs. Supply Voltage for derating information. Heat
sinking the parts by attaching them to a PCB improves temperature performance.
5.
There is no maximum magnetic field that will cause damage to the device.
- 45 www.nve.com phone: 952-829-9217 fax: 952-829-9189
GT Sensors
Precision Gear Tooth and Encoder Sensors
NVE’s GT Sensor products are based on a Low Hysteresis GMR sensor material and are designed
for use in industrial speed applications where magnetic detection of gear teeth and magnetic encoder
wheels is required.
GT Sensors with both analog and digital outputs are available. The analog parts feature the large signal
and robust characteristics which NVE’s GMR materials are known for (NVE’s GMR sensors are not
damaged by extremely large magnetic fields). The sensor elements themselves are designed to provide
usable output with even the smallest gear teeth. Single and double output versions are available; the
second output is phase shifted with respect to the first, to provide quadrature for determining direction.
The digital sensors take advantage of the high
performance characteristics of GMR sensors to
provide a 50% duty cycle output with a wide
tolerance in airgap and temperature variations.
GT Sensors are available in low-profile MSOP8,
TDFN SO8, and TDFN6 packages, in order to
fit into the tightest possible spaces. An
evaluation kit is available, containing a selection
of sensors, magnets, and PCBs, so that the user
can test the parts in their application
- 46 www.nve.com phone: 952-829-9217 fax: 952-829-9189
ABL Sensors
Single/Double Bridge Gear Tooth And Encoder Sensors
Features:
•
•
•
•
•
•
•
Large Airgap
Direct Analog Output
DC (Zero Speed) Operation
Sine / Cosine Outputs
Precise Spacing and Phase Shifting Between Sensor Elements
Excellent Temperature and Voltage Performance
Small, Low-Profile Surface Mount Packages
Applications:
•
•
•
Linear and Angular Speed Sensing
Linear and Angular Position Sensing
Direction Detection
Description:
The ABL-Series GT Sensors are differential sensor elements that provide an analog sinusoidal output
signal when used with a bias magnet and gear tooth or a magnetic encoder. These chips use NVE’s
proprietary GMR sensor elements featuring an extremely large output signal from the raw sensor
element, which is stable over the rated temperature and voltage range. As a result, ABL-Series GT
Sensors feature excellent airgap performance and an extremely stable operating envelope as well as the
robust reliability characteristics that NVE sensors are known for.
Three different standard spacings are available for use with fine and coarse pitch encoders and gear
teeth. Both single bridge and double bridge configurations are also available. Double bridges are used
to generate sine/cosine outputs. In addition to the standard spacings, NVE can provide custom spacings
and multiple sensor elements tailored to the individual customer’s application for a nominal design and
tooling charge. Contact NVE for further details.
For digital output applications, these sensors can be used with NVE’s DD001-12 signal processing IC
which converts their output into a 50% duty cycle modulated current signal. This IC allows placement
of the ABL sensor in a very small housing with wires running from the sensor to the signal processing
IC in a remote location. Thus ABL-Series sensors can be used in M8 and smaller housings.
- 47 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Specifications:
Parameter
Single Bridge Resistance at 25°C
Input Voltage
Operating Temperature Range
Offset Voltage
Linear Range
Linearity of Output
Hysteresis
Saturation of GMR Sensor Elements
Single Resistor Sensitivity
Max Output
Temperature Coefficient of Resistance
ESD
Storage Temperature Range
Min
4K
1
<1
-50
-4
±5
98
Typ
5K
Max
7K
1
30
+150
+4
±100
2
+180
-180
.04
80
+0.11
400
-65
+170
Unit
Ohms
Volts
°C
mV/V
Oe
2
%
2
%
3
Oe
4
%∆R/Oe
mV/V
%/°C
5
V
°C
Notes:
1.
ABL-Series sensors have a purely ratiometric output. They will operate with input voltages of 0.1 V or lower. The output
signal will scale proportionally with the input voltage. Maximum voltage will be limited by the power dissipation
allowable in the package and user installation. See the package section for more details.
2.
3.
Linearity and Hysteresis measured across linear operating range, unipolar operation.
Application of a magnetic field in excess of this value will saturate the GMR sensor elements and no further output will be
obtained. No damage occurs to the sensor elements when saturated. NVE GMR sensors will not be damaged by any large
magnetic field.
4.
Percent change in resistance with application of 1 Oersted of magnetic field; corresponds to an 8% change in resistance
5.
Pin-to-pin voltage, Human Body Model for ESD.
with 200 Oersteds of applied magnetic field (1 Oersted = 1 Gauss in air, or 0.1 milliTesla).
- 48 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Center of Die
and Package
0.125
IC Drawings:
0.140
ABL004
1.000
0.500
ABL005
0.500
0.250
ABL014
1.000
1.000
0.250
0.250
0.500
ABL015
0.500
0.500
0.125 0.125
0.250
- All dimensions in mm
- All resistors are 5kΩ
- Sensor elements are located symmetrically about the center of the IC.
Note: ABL006 ABL016 Sensor Element Size and Spacing Not Shown
- 49 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Schematics:
VCC
ABL004, ABL005, ABL006
Schematic
R4
R1
OUT-
OUT+
R3
R2
GND
VCC1
VCC2
ABL014, ABL015, ABL016
Schematic
(Dual Bridge)
R4
R8
R1
OUT-1
OUT+1
OUT-2
R3
R2
R5
OUT+2
R7
R6
GND1
GND2
Part Numbers and Configurations:
Part Number
ABL004-00
ABL005-00
ABL006-00
ABL014-00
ABL015-00
ABL016-00
ABL004-10
ABL005-10
ABL006-10
ABL014-10
ABL015-10
ABL016-10
Single or Dual
Bridge
Single
Single
Single
Dual
Dual
Dual
Single
Single
Single
Dual
Dual
Dual
Element
Spacing
(Microns)
1000
500
300
1000
500
300
1000
500
300
1000
500
300
Phase Shift
Between
Bridges
(Microns)
NA
NA
NA
500
250
150
NA
NA
NA
500
250
150
Package
Marking
FDB
FDC
FDL
FDD
FDF
FDM
FDG
FDH
FDN
FDJ
FDK
FDP
- 50 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Packages:
The ABL-Series parts are available in MSOP8 and TDFN6 packages. Please see the package drawing
section in the Appendix for dimensions. Please note that for dual differential sensors in the TDFN
package the power and ground connections for both bridges are common.
Pin Configuration:
Direction of Sensitivity
MSOP8 Package
Out+
VCC
No Connect
ABL004-00,
ABL005-00,
ABL006-00
No Connect
Ground
Ground1
No Connect
Out-1
No Connect
Out+1
Out-
VCC2
Out+2
ABL014-00,
ABL015-00,
ABL016-00
Out-2
Ground2
VCC1
Direction of Sensitivity
TDFN6 Package
Out+
VCC1
VCC2
Ground1,
VCC
Ground2
No Connect
Gnd
ABL004-10,
ABL005-10,
ABL006-10
No Connect
Out-1
Out+1
Out-
ABL014-10,
ABL015-10,
ABL016-10
Out+2
Out-2
- 51 www.nve.com phone: 952-829-9217 fax: 952-829-9189
AKL Sensors
Digital Output Gear Tooth And Encoder Sensors
Features:
•
•
•
•
•
•
Large Airgap
50% Duty Cycle
DC (Zero Speed) Operation
Precise Spacing Between Sensor Elements
Excellent Temperature and Voltage Performance
Small, Low-Profile Surface Mount Package
Applications:
•
•
•
•
Anti-lock Brake System Sensors
Transmission Speed Sensors
Industrial Linear and Angular Speed Sensing
Linear and Angular Position Sensing
Description:
NVE offers these products specifically for use as sensors for gear tooth wheels or magnetic encoders
with a digital output signal. The pulse output from the sensor corresponds with the gear teeth passing
in front of it. When a gear tooth or magnetic pole is in front of the sensor, the sensor’s output goes
high; when the gear tooth or magnetic pole moves away, the output returns to low. This repeats at
every tooth/pole resulting in a pulse train output that provides speed information from the gear or
encoder. Three part numbers are currently available: the AKL001-12 is designed for gear teeth or
encoders with a pitch of 2.5 to 6 mm, the AKL002-12 for a pitch of 1 to 2.5 mm, and the AKL003-12
for a pitch of 0.6 to 1.5 mm.
In order to minimize the number of wires leading to the sensor, the part is configured as a two-wire
device. The two output states are indicated with a change of current through the part. Therefore, when
the part is in the digital low state, current is about 3 mA. When the part is in the digital high state, the
current increases to about 10 mA. If necessary, the two-wire output of the AKL-Series parts can be
easily converted to a three-wire current sinking output with the circuit shown in the GT Sensor
applications section.
The parts are rated for the full automotive and industrial temperature range, -40°C to +150°C. They
feature reverse battery protection and have an operational voltage range of 4.5V to 36V. They operate
from DC to 10 kHz. The parts are available in low-profile, surface mount TDFN SO8 packages.
- 52 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Specifications:
Parameter
Input Voltage
Supply Current in Off State
(Input Voltage=12V)
Supply Current in On State
(Input Voltage=12V)
Output Duty Cycle
Operating Temperature Range
AKL001-12 Airgap, Over Full Temperature and
4
Voltage Range
AKL002-12 Airgap, Over Full Temperature and
4
Voltage Range
AKL003-12 Airgap, Over Full Temperature and
4
Voltage Range
Frequency of Operation
ESD
Min
4.5
3.2
Typ
4.0
Max
36
4.8
Unit
1
Volts
2
mA
7.0
8.0
9.0
mA
40
-40
1.0
50
60
+150
3.5
%
°C
mm
1.0
2.5
mm
1.0
2.0
mm
10K
Hz
3
V
0
2000
2
Absolute Maximum Ratings
Parameter
Limit
Supply Voltage
45V
Reverse Battery Voltage
-60V
Continuous Output Current
16mA
Junction Temperature Range
-40°C to +170°C
Storage Temperature Range
-65°C to +170°C
Signal Output
10
Current
Output
(mA)
5
Time
Notes:
1.
The supply voltage must appear across the power and ground terminals of the part. Any additional voltage drop due to the
2.
Supply currents can be factory programmed to different levels, for example 3 mA and 6 mA, or 7 mA and 14 mA;
3.
Pin-to-pin voltage, Human Body Model for ESD
4.
Airgap measured with standard ferrous gear tooth; contact NVE for details.
presence of a series resistor is not included in this specification.
contact NVE for details.
- 53 www.nve.com phone: 952-829-9217 fax: 952-829-9189
IC Drawings:
The AKL-Series products use the ABL sensor elements described earlier in this section. The AKL00112 part uses the ABL004 sensor element, the AKL002-12 uses the ABL005 sensor element, and the
AKL003-12 uses the ABL006 sensor element. Please see the IC drawings in the ABL-Series section
for more information.
Part Numbers and Configurations:
Single or Dual
Bridge
Single
Single
Single
Part Number
AKL001-12
AKL002-12
AKL003-12
Element
Spacing
(Microns)
1000
500
300
Marking
Part Number
Part Number
Part Number
Schematic:
A block diagram of the AKL-Series parts is shown below:
Voltage
Regulator
3.3V
Switching
Current
Source
GMR
Bridge
A
EEPROM
Gain
Offset
Detector
A
Current Level
Packages:
The AKL-Series parts are available in the TDFN8 SO8 package. Please see the package drawing
section in the Appendix for dimensions.
- 54 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Pin Configuration:
TDFN8-SO8 Package
TEST
TEST
TEST
TEST
AKL001-12
AKL002-12
AKL003-12
BRIDGE+
BRIDGEVCC
Note: Bridge + and Bridge - are provided for
analysis purposes only. NVE does not
recommend connecting these pins in a
production product for ESD and loading
reasons. Also, all pins labeled “Test” must be
floating, i.e., not connected to each other or
any other circuit node.
GND
Sensitivity
- 55 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Circuit Board Sensor Products
Circuit Board Sensor Products
AG21x-07 Cylinder Position Sensors
PCB Assemblies for Pneumatic Cylinder Applications
Features:
•
•
•
•
•
Precision Magnetic Operate Point
Three-Wire Current Source or Current Sink Output
Wide Operating Temperature Range
Short Circuit, Transient, and ESD Protected
Conforms to EN 60947-5-2 Standards for Switchgear
Applications:
•
•
Pneumatic Cylinder Position Sensing
General Magnet Position Sensing
Description:
The AG211-07 and AG212-07 PCB assemblies are small, sensitive magnetic sensors for use in
pneumatic cylinder position sensing and other position sensing applications. They are designed to be
potted or injection molded by the customer to make a complete magnetic sensor assembly with a cable
attached and enclosed in a plastic housing. The PCB assemblies include an NVE AD9xx magnetic
sensor, a DB001 signal processing IC, plus surrounding signal processing and filtering components.
These parts provide a precise, temperature stable magnetic operate point and will source up to 200 mA
of output current. They also feature reverse battery protection and short circuit protection as well as
immunity to transients as specified in US and European standards such as EN60947-5-2.
The assemblies have a yellow LED to indicate the presence of the magnetic field, and are sized to fit
into small package housings. Output from the parts are open-collector PNP transistors in currentsourcing configuration. The customer is required to limit the output current to the desirable level, from
5 mA to 200 mA, with an external load resistor.
- 56 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Circuit Board Sensor Products
AG211-07 Photo
Top View
Bottom View
AG212-07 Photo
Top View
Bottom View
General Electrical Characteristics
Parameter
Min
Typical
Max
Input Voltage Range
4.5
30
2
Temperature Range
-20
85
1
Magnetic Operate Point
21
28
34
1
Magnetic Release Point
5
14
Reverse Battery Protection
-30
LED
Yellow
VCC - VOH
(Maximum Output Voltage
2
Drop Across Part)
Output Current
5
200
Supply Current
2.5
4.5
Short Circuit Protection Limit
350
Unit
V
°C
Oe
Oe
V
V
mA
mA
mA
Notes:
1.
See AD924-00 data in GMR Switch section of this catalog.
2.
These parts are assembled with high temperature solder; overmolding at temperatures up to 210°C for 10 seconds is
approved.
- 57 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Circuit Board Sensor Products
PCB Assembly Dimensions:
Part Number
Length, inches (mm)
Width, inches (mm)
Height, inches (mm)
AG911-07
0.755 (19.2)
0.165 (4.2)
0.100 (2.55)
AG912-07
0.540 (13.7)
0.115 (2.9)
0.085 (2.16)
Functional Block Diagram for AG211 and AG212:
Source
Cap
Cap2
t1 Cap
Vreg
AD9xx-xx
Cross Axis
Vreg
Sink
In
ShortL
LED
VCC
Ground
VCC
FFD
NVE
Ground
VCC
ISC
Source
Out
Out
Sink Out
t2 Cap
Ground
Wiring Diagram:
Note: the dotted line pad is on the
backside of the PCB.
Ground
Out
VCC
- 58 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Circuit Board Sensor Products
AG-Series Currency Detection Sensors
Sensor Arrays for Currency / Magnetic Media Detection
Features:
•
•
•
Arrays of Sensor Elements for Broad Area Coverage
No Contact with Media Required
Capable of Detecting Very Low Magnetic Fields
Applications:
•
•
•
Currency Detection and Validation
Other Magnetic Media Applications (Checks, Credit Cards, etc.)
General Area Sensing for Low Magnetic Fields
Description:
These products are custom-built PCB assemblies for customer specific applications. They typically
contain 20 to 60 analog GMR sensor elements, most often the AA002, AAH002, or AAL002 sensors.
These sensors are mounted on a PCB, most often using Chip-On-Board (COB) assembly techniques,
so that the sensor elements can be placed very close together. In addition, a coil on the PCB is
provided on many of these designs, so that a current can be fed through the coil to provide a magnetic
bias field at the sensors.
In a typical currency detection application, this PCB assembly is positioned approximately 1 mm from
the currency path. The bank note is typically magnetized with a permanent magnet before it reaches
the sensor array. The residual magnetization in the magnetic ink or stripe of the currency is detected by
the sensor array. This information is then analyzed to determine if the currency is genuine. See the
figure below:
Sensor
Array
N
Bank Note
S
Feed Rollers
Magnet
- 59 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Circuit Board Sensor Products
Since every application is different in terms of circuit board and sensor configuration, NVE does not
offer a standard product for this application. However, NVE is prepared to rapidly prototype these
assemblies for customer evaluation at a nominal cost. Please contact NVE for details.
- 60 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
Peripheral Integrated Circuits
In addition to GMR Sensor products, NVE has begun designing and manufacturing accessory products
for our sensors. These products are designed to be used with NVE’s sensors, or in some cases as standalone parts, to provide higher level signal processing capabilities coupled with the robust performance
characteristics that NVE products are known for.
DB-Series Power Switch ICs – In many industrial control applications, a digital current output of up
to 200 mA is required. NVE’s DB-Series parts are designed to meet these requirements. They feature
transient protection to meet rigid EMC and ESD standards, thermal shutdown for temperature
protection, reverse battery protection, a regulated voltage output, an on-chip LED driver, and short
circuit protection of the current drive output transistor. The DB001-00 is designed specifically to work
together with NVE’s AD9xx-00 short circuit protected GMR switch to create a very small IC
combination suitable for use in miniature sensor assemblies. The DB002-02 is designed to take a
generic digital input from any source, including inductive and photo sensors, and provide the digital
current output.
DC Series Voltage Regulator ICs – These ICs are designed for use in high voltage, low current
applications. They provide a wide input voltage range, up to 60V, and are available in 3.3V and 5.0V
outputs. They feature reverse battery protection and excellent immunity to transients and noise
allowing for the reduction or elimination of filtering devices at the PCB level. They are available in the
TDFN6 package, which features a small PCB footprint (2.5 mm x 2.5 mm) and an exposed lead frame
on the back for heat sinking to the PCB. DC series voltage regulators meet 42V automotive standards.
DD-Series Signal Processing IC for Analog GT Sensors – The DD001-12 is designed to be
interfaced with an NVE ABL-Series GT Sensor to provide a digital output signal with excellent
stability characteristics. It can be located away from the sensor so that the ABL package (MSOP8 or
TDFN6) can be placed in a small remote housing, resulting in the absolute minimum size sensor
package. The DD001-12 can also be used with other sensing devices which feature a sinusoidal output,
to provide the same stable current modulated signal that it provides for NVE’s ABL-Series GT
Sensors.
- 61 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
DB001-00 Series Power Switch IC
Features:
•
•
•
•
•
•
Designed to Work with AD9xx
High Current Output
Short Circuit, Reverse Battery, and Transient Protection
LED Driver
Excellent Temperature and Voltage Performance
Small, Low-Profile Surface Mount Package
Applications:
•
•
Output Driver for Sensor Assemblies
Usable with Magnetic, Inductive, and Photo Sensors
Description:
The DB001-00 signal processing IC is designed to take the digital input signal from NVE’s AD9xx
GMR Switch and provide a high current switched output corresponding with the sensor input. The part
functions as the “front end” of a complete sensor assembly and includes protection against short
circuits and high voltage transients from capacitive and inductive loads. The parts also feature thermal
shutdown circuitry and reverse battery protection. It provides a regulated output voltage for the sensor
and other components in the assembly and an LED driver to indicate an “ON” condition.
Together, the AD9xx GMR Switch and the DB001-00 signal processing IC form the bulk of the signal
processing required for pneumatic cylinder position sensing electronics. Using these two ICs, the end
user only requires a few capacitors and an LED in order to implement the complete sensor assembly
circuit. In addition, both the AD9xx part and the DB001-00 part come in MSOP8 packages, so that the
customer can implement the complete design on an extremely small PCB.
If ultra-miniaturization is desired, the DB001 part can be obtained in die form for COB (Chip On
Board) or flip-chip assembly.
Part Numbers and Configurations:
Part
Number
DB001-00
DB001-01
Input
Current Sinking from
AD9xx-00
Current Sinking from
AD9xx-00
Die Size (mm)
Package
Marking
1.48 x 2.25
MSOP8
FFD
1.48 x 2.25
Raw IC
30284D
- 62 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
Schematic:
A block representation of the DB001-00 series part is shown below:
3.3 Volts
Voltage
Regulator
VCC
Vreg
Input
Sink Out
Amplifier
Thermal
Shutdown
Source Out
LED
Ground
ISC
Packages:
Please see the package drawing section in the Appendix for dimensions of the MSOP8 package.
Pin Configuration:
VCC
ISC
Source
Out
Sink Out
Vreg
NVE
FFD
In
LED
Ground
- 63 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
Application Circuits:
DB001-00 in Current Sourcing Output Configuration:
Vreg
Source
Cap
Cap2
t1 Cap
AD9xx-xx
Cross Axis
VCC
Vreg
Sink
In
ShortL
LED
VCC
Ground
FFD
NVE
Ground
VCC
ISC
Source
Out
Out
Sink Out
t2 Cap
Ground
Note:
For current-sinking applications, connect “Source Out” to Ground; use “Sink Out” pin as output.
Electrical characteristics (-40°C to +125°C, unless otherwise noted)
Parameter
Min
Typ
Max
Input Voltage
4.5
30
Vreg Voltage
3.0
3.3
3.6
Vreg Output Current
10
Switched Output Current
200
Capacitive Load
100
Off State Output Leakage Current
300
Bias Current (output off)
1.0
LED Drive Current
3
Thermal Shutdown Temperature
200
Sinking Input Current Required
100
Output Transistor Saturation Voltage
0.5
1.1
1.5
Output Short Circuit Current
0.5
0.84
1.0
Absolute maximum ratings*
Parameter
Limit
Input Voltage
36 V
Reverse Battery Protection
-36 V
Output Current
250 mA
Junction Temperature Range, TJ
-40°C to +170°C
Storage Temperature Range
-65 °C to +170°C
Units
V
V
mA
mA
nF
µA
mA
mA
°C
µA
V
A
*Stresses beyond those listed under “Absolute
maximum ratings” may cause permanent
damage to the device. These are stress ratings
only and functional operation of the device at
these or any other conditions beyond those
indicated under “Electrical characteristics” is
not implied.
Notes:
1.
This part has reverse battery protection to -36V
2.
Due to package size, MSOP8 package contains 3-letter code to designate part type.
- 64 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
DB002-02 Series Power Switch IC
Features:
•
•
•
•
•
•
Designed to Work with Magnetic, Inductive, or Photo Sensors
Up to 300 mA Continuous Current Output
Short Circuit, Reverse Battery, Transient and Thermal Protection
On-Chip LED Driver
Excellent Temperature and Voltage Performance
Available in SOIC8 Package or in Die Form
Applications:
•
•
Output Driver for Sensor Assemblies
Usable with Magnetic, Inductive, and Photo Sensors
Description:
The DB002 series power switch IC is designed to take a digital input from a sensor element and
provide a high current switched output corresponding with the sensor input. The part functions as the
“front end” of a complete sensor assembly and includes protection against short circuits and high
voltage transients from capacitive and inductive loads. The part also features thermal shutdown
circuitry and reverse battery protection. It provides a regulated output voltage for the sensor and other
components in the assembly and an LED driver to indicate an “ON” condition.
The DB002 is available in the SOIC8 package (p/n DB002-02), as well as in die form (p/n DB002-01).
It is designed to work with NVE’s AD1xx GMR Switch products, or any other current sourcing or
CMOS/TTL digital output sensor element such as an inductive sensor or a photo sensor.
Part Numbers and Configurations:
Part
Number
DB002-01
DB002-02
Input
Any Current Sourcing or CMOS/TTL
Compatible Digital Output Device
Any Current Sourcing or CMOS/TTL
Compatible Digital Output Device
Die Size
(mm)
Package
1.89 x 2.85
Die
1.89 x 2.85
SOIC8
Marking
30304H
(Chip ID Number)
- 65 www.nve.com phone: 952-829-9217 fax: 952-829-9189
DB002-02
Peripheral Integrated Circuits
Functional Block Diagram and Pinout:
VCC
Voltage
Regulator
5.0 Volts
Vreg
Input
Sink Out
Amplifier
Thermal
Shutdown
Source Out
LED
Short Circuit Detection
Circuitry
Ground
Input
Ground
Vreg
Delay
Cap
DB002-02
VCC
Source
Out
Sink
Out
LED
Packages:
Please see the package drawing section in the Appendix for dimensions of the SOIC8 package.
- 66 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
Example Application Circuit:
N/C
VCC
Vreg
AD124-00
N/C
N/C
Ground
Source
Cross Axis
Delay
VCC
DB002-02
NVE
VCC
LED
N/C
In
Source
Out
N/C
Ground
Sink Out
Out
Delay
Cap
Ground
Notes on Operation:
1.
A capacitor of at least 1nF value must be placed between the Delay pin and ground on the IC.
2.
NVE recommends a bypass capacitor between VCC and Ground, 10nF or larger
3.
In noisy environments a capacitor may be used on Vreg if necessary, up to 100nF.
Electrical characteristics (-40°C to +125°C, unless otherwise noted)
Parameter
Min
Typ
Max
Input Voltage
6.2
30
Vreg Voltage
4.5
5.0
5.5
Vreg Output Current
10
Switched Output Current
300
Capacitive Load
100
Off State Output Leakage Current
300
Bias Current (output off)
1.4
LED Drive Current
3
Thermal Shutdown Temperature
200
Sourcing Input Current or CMOS/TTL
5
Drive Current Required (DB002-02)
Turn-On Voltage at Input Terminal
3.0
Turn-Off Voltage at Input Terminal
2.0
On/Off Hysteresis
0.25
Output Transistor Saturation Voltage
0.5
1.1
1.5
Short Circuit Protection Turn-On
400
650
Current
Output Short Circuit Current
0.5
0.84
1.0
Absolute maximum ratings*
Parameter
Limit
Input Voltage
36V
Reverse Battery Protection
-36V
Output Current
350mA
Junction Temperature Range, TJ
-40°C to +170°C
Storage Temperature Range
-65 °C to +170°C
Units
V
V
mA
mA
nF
µA
mA
mA
°C
µA
V
V
V
V
mA
A
*Stresses beyond those listed under “Absolute
maximum ratings” may cause permanent
damage to the device. These are stress ratings
only, and functional operation of the device at
these or any other conditions beyond those
indicated under “Electrical characteristics” is
not implied.
- 67 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Peripheral Integrated Circuits
DC-Series Voltage Regulators
High Voltage, Low Power Voltage Regulators
Features:
•
•
•
•
•
•
Input Voltage to 36VDC (Max Rating 45VDC)
5.0V and 3.3V Regulated Output
Reverse Battery Protection
Excellent Immunity to Transients and ESD
High Temperature Operation
Small, Low-Profile Surface Mount Package
Applications:
•
•
Industrial Sensors and Controls
Automotive Sensors and Controls
Description:
The DC series voltage regulator ICs are designed for use in harsh, noisy environments where immunity
to large voltage transients and acceptance of high input voltages are required. These regulators protect
the sensitive electronic components downstream, while providing a stable regulated supply voltage.
They are rated for high temperature operation, up to +170°C. The low-profile small footprint package
features an exposed die attach pad, for direct heat sinking to the circuit board.
Specifications
Electrical characteristics (-40°C to +175°C, unless otherwise noted)
Parameter
Min
Typ
Max
Input Voltage (DC001-10)
4.5
36
Output Voltage (DC001-10)
3.0
3.3
3.6
Input Voltage (DC002-10)
6.2
36
Output Voltage (DC002-10)
4.5
5.0
5.5
Output Current
20
Bias Current at Zero Output Current
900
Absolute maximum ratings*
Parameter
Limit
Input Voltage
45V
Reverse Battery Voltage
-60V
Output Current
25mA
Junction Temperature Range, TJ
-40°C to +170°C
Storage Temperature Range
-65 °C to +170°C
Units
Volts
Volts
Volts
Volts
Milliamps
Microamps
*Stresses beyond those listed under “Absolute
maximum ratings” may cause permanent damage
to the device. These are stress ratings only, and
functional operation of the device at these or any
other conditions beyond those indicated under
“Electrical characteristics” is not implied.
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Peripheral Integrated Circuits
Notes:
1.
Power dissipation rating for TDFN6 package in free air is 320°C/Watt. Soldering the package to a PCB, including the die
attach paddle, improves temperature performance substantially. The input voltage and output current are limited by thermal
power dissipation at the package.
2.
Due to package size, TDFN6 package has a three-letter code to designate part type.
Package:
Please see the package drawing section in the Appendix for dimensions of the TDFN6 package.
Pin Configuration
Vreg (Out)
No Connect
VCC (In)
No Connect
DC001-10,
DC002-10
Ground
No Connect
Note: The die attach pad is exposed on the back of this package. NVE recommends that it be connected to
the ground pin and the PCB for improved temperature performance.
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Peripheral Integrated Circuits
DD-Series Signal Processing ICs
For use with ABL-Series Sensors
Features:
•
•
•
•
•
•
Converts Analog Sensor to Digital Operation
Two-Wire Output
50% Duty Cycle
DC (Zero Speed) Operation
Excellent Temperature and Voltage Performance
Small, Low-Profile Surface Mount Package
Applications:
•
•
•
Linear and Angular Speed Sensing
Linear and Angular Position Sensing
Direction Detection
Description:
The DD-Series signal processing IC is designed to take an analog, sinusoidal input signal such as that
provided by NVE’s ABL-Series sensors and convert it to a two wire, current modulated digital output.
Inputs as small as 2 mV peak-to-peak can be provided to the IC, along with large signal offsets. The
DD001-12 part will provide a 50% duty cycle digital output signal.
The DD001-12 part contains a voltage regulator circuit, programmable amplifier, offset detection and
correction circuitry, and an EEPROM for setting gain and current levels. The voltage regulator output
(3.3V) is used to power the external sensor element, which should be connected between VREG and
VGND. Nominal current levels for the current modulated output are 3 mA and 10 mA. These can be
factory programmed to different levels for specific customer requirements.
Using the DD-Series signal processing IC allows the user to put the sensor element, which can very
small in a remote location, and pipe the signals from the sensor to the DD001-12 for digitizing
purposes. In addition, if two phase shifted sensor outputs are available (such as with the ABL014-00,
ABL015-00, and ABL015-00sensors), two DD001-12 parts can be used to provide two phase shifted
digital signals, for the purpose of detecting the direction of the gear tooth or encoder wheel.
The two-wire output of the DD001-12 can be easily converted to a three-wire current-sinking output
with the circuit shown in the GT Sensor applications section.
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Peripheral Integrated Circuits
Specifications:
Parameter
Input Voltage
Input Voltage Signal
Input Current
Supply Current – Off
(Input Voltage=12V)
Supply Current – On
(Input Voltage=12V)
Output Duty Cycle
Regulated Voltage Output
Current Supplied by Regulated Voltage Output
Operating Temperature Range
Frequency of Operation
ESD
Absolute Maximum Ratings
Parameter
Supply Voltage
Reverse Battery Voltage
Output Current
Junction Temperature Range
Storage Temperature Range
Min
4.5
2
Typ
3.0
Max
36
200
10
3.8
Unit
1
Volts
2
mV
µA
3
mA
2.2
7.0
8.0
9.0
mA
40
3.0
50
3.3
60
3.6
10
+150
10k
-40
0
2000
3
%
Volts
mA
°C
Hz
4
V
Limit
45V
-60V
16mA
-40°C to +170°C
-65°C to +170°C
Signal Output
10
Current
Output
(mA)
5
Time
Notes:
1.
The supply voltage must appear across the power and ground terminals of the part. Any additional voltage drop due to the
2.
Input signal range can be adjusted by programming the amplifier gain to a specific value; contact NVE for details.
3.
Supply currents can be factory programmed to different levels, for example 3 mA and 6 mA, or 7 mA and 14 mA; contact
4.
Pin-to-pin voltage, Human Body Model for ESD.
presence of a series resistor is not included in this specification.
NVE for details.
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Peripheral Integrated Circuits
Schematic:
A block representation of the DD-Series parts is shown below:
Vreg
Voltage
Regulator
3.3V
Switching
Current
Source
Bridge +
A
Offset
Detector
Bridge -
A
EEPROM
Gain
Current Level
Packages:
The DD-Series parts are available in the TDFN SO8 package. Please see the package drawing section
in this catalog for dimensions.
Pin Configuration:
TDFN-SO8 Package
Test
Test
Vreg
VCC
Ground
DD001-12
Test
Bridge+
Note: Bridge + and Bridge - should be
connected only to the sensor element outputs
for ESD and loading reasons. Vreg can supply
up to 10 mA at 3.3V (330Ω load). Also, all
pins labeled “Test” must be floating, i.e., not
connected to each other or any other circuit
node.
Bridge-
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Evaluation Kits
Evaluation Kits
In order for our customers to evaluate GMR sensors in their application NVE makes available several
evaluation kits, at nominal cost, so that customers can try the actual parts in their application. These
kits are described below:
AG001-01 - Analog Sensor Evaluation Kit
This kit features several types of NVE’s AA and AB-Series parts, a selection of permanent
magnets for activation or bias purposes, and circuit boards to mount the parts for testing purposes.
AG003-01 - Current Sensor Evaluation Kit
This kit features a specially designed circuit board with traces running under the sensor elements.
The customer can try different current levels to see the output from the sensor.
AG910-07, AG911-07 - GMR Switch Evaluation Kits
These kits include several GMR Switch parts with different magnetic operate points and different
output options such as current sink and current source. In addition, magnets and circuit boards for
mounting the parts in the application are included. In the AG910-07 kit, a socket for easy testing
of the MSOP-8L package is also included.
AG920-07 -
GT Sensor Evaluation Kit
NVE’s newest evaluation kit includes analog and digital versions of the GT sensor product line
plus our DD001-12 stand-alone signal processing IC. A variety of PCB configurations are
provided so that the parts can be tested in different housing and barrel sizes including the M8
housing. Magnets for biasing are also included.
Evaluation kits may be ordered direct from NVE’s web site or from our authorized distributors. See
NVE’s web site for the list of authorized distributors.
- 73 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Evaluation Kits
AG001-01 Analog Sensor Evaluation Kit
The NVE GMR Engineering Evaluation Kit (PN AG001-01) was created as an aid to the technical user
of GMR sensors to facilitate laboratory experimentation and development. The kit consists of an
assortment of NVE sensors, printed circuit boards and permanent magnets sufficient to demonstrate
sensor functionality in the laboratory. The kit consists of the following:
Part Number
Quantity
Description
AA002-02
AAH002-02
AAL002-02
AA003-02
AA004-02
AA005-02
AA006-02
AB001-02
AG004-06
AG005-06
SN 12031
SN 12030
2
1
1
2
2
2
2
2
2
2
2
2
15 Oe/5 kΩ Field Sensor
6 Oe/2 kΩ Field Sensor
15 Oe/5 kΩ Field Low Hysteresis Sensor
20 Oe/5 kΩ Field Sensor
50 Oe/5 kΩ Field Sensor
100 Oe/5 kΩ Field Sensor
50 Oe/30 kΩ Field Sensor
250 Oe/5 kΩ Field Gradient Sensor
Long PCB- 3.0” x 0.3”
Square PCB- 0.5” x 0.5”
Ceramic 5- Disc Magnets
Ferrite Rectangular magnets
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Evaluation Kits
AG003-01 Current Sensor Evaluation Kit
The NVE GMR Current Sensor Evaluation Assembly (P/N AG003-01) was created to facilitate
laboratory experimentation and development using GMR current sensors. The kit consists of (4) four
NVE current sensors (P/N AA003-02) assembled to a printed circuit board (P/N AG002-01). Please
note that the AA003-02 was selected for inclusion in this kit because it is a good medium sensitivity
current sensor. In fact, any of NVE’s AA sensor products can be used in this application for more or
less sensitivity to the magnetic field generated by the current. The PCB included in the kit has (4) four
trace geometries to simulate various PCB current ranges. The details are as follows:
1
Trace
no.
1
2
Trace Width
(inches)
0.090
0.060
Maximum Trace Input
Current (A)
±9.0
±6.0
Nominal Sensitivity
([mV/V]out/Ain)
3.5
3.7
3
4
0.010
7 x 0.010
±0.25
±0.25
4.0
20.0
Notes:
1.
The maximum current is based on the rated current carrying capability of each trace geometry.
2.
The minimum current the assembly can sense is arbitrary. The absolute value is dependent on many system design
3.
For functional characteristics of the AA003-02 current sensor refer to the AA Sensors section of this catalog.
parameters and must be determined by the user.
4.
Refer to NVE’s Engineering & Application Notes, Appendix APP 003, “GMR Current Sensing” for additional technical
details.
5.
The AG003-01 assembly can be subdivided into (4) four separate sub-assemblies. All connections to each input trace and
current sensor are isolated on each sub-section.
2.00
NVE
NVE
AC00401
Trace 1
Current Sensor Evaluation Board
1-800-GMR-7141
AG002-01
Trace 2
NVE
AC00401
Trace 3
NVE
AC00401
NVE
AC00401
Trace 4
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Evaluation Kits
AG910-07 and AG911-07 GMR Switch Evaluation Kits
These kits were created to facilitate laboratory
experimentation and development using NVE’s GMR
Switch Digital Output Sensors. The kits consist of
sixteen distinct NVE GMR Switches that span the
magnetic field range and output types available in the
AD-Series sensors. All sensors in this kit are
packaged in the MSOP8 miniature surface mount
package. The kits also include a ceramic bar magnet
and printed circuit boards (PCBs) for testing in the
actual application. In addition, the AG910-07 kit
includes a high temperature (175°C) MSOP8 ZIF
socket with Kelvin contacts.
GMR Switch Digital Evaluation Kits Parts List
Part
Designator
Part Marking
Output type
AD004-00
BBH
AD005-00
BBG
AD006-00
BBJ
Single
AD020-00
BBK
Current
AD021-00
BBB
Sink
AD022-00
BBC
AD023-00
AD024-00
ADH025-00
AD105-00
AD122-00
AD824-00
AD924-00
AD320-00
AD324-00
AD624-00
AD724-00
AG910-06
BBD
BBF
MBL
DBG
DBC
MBF
NBF
GBK
GBF
KBF
LBF
N/A
Single Source
“
Dual Output
with SCP
Sink/Sink
“
Sink/Source/Vreg
Sink/Sink/Vreg
N/A
AG918-06
AG919-06
SN 12100
N/A
N/A
N/A
N/A
N/A
N/A
SN 12032
N/A
N/A
Description
See
GMR Switch
Section of
This Catalog
l”x2” PCB Board
(AG910-07 Kit Only)
.25” X 2” PCB Board
.25” X 2” PCB Board
MSOP8 ZIF Socket
(AG910-07 Kit Only)
Ceramic Magnet,l”x0.25”x0.39”
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Evaluation Kits
AG920-07 GT Sensor Evaluation Kit
This kit was created to facilitate laboratory
experimentation and development using NVE’s GT
Sensor products. Because of the wide variety of
mechanical orientations where these sensors can be
used, this kit contains a large variety of circuit boards
to simplify the customer’s fixturing and testing of the
parts. Included in the kit are one of each type of
NVE’s GT Sensor products, both analog and digital,
plus two of the DD001-12 signal processing ICs to
convert the analog output of the ABL sensors digital.
The contents are listed below:
Quantity
1
1
1
Part Number
ABL004-00
ABL005-00
ABL014-00
Marking
FDB
FDC
FDD
1
ABL015-00
FDF
1
AKL001-12
P/N
1
AKL002-12
P/N
2
2
2
1
DD001-12
AG915-06
AG914-06
AG918-06
P/N
N/A
N/A
N/A
1
AG919-06
N/A
1
1
AG913-06
AG916-06
N/A
N/A
1
AG917-06
N/A
1
AG911-06
N/A
1
AG912-06
N/A
5
5
12216
12217
N/A
N/A
Description
Single Differential Sensor, 1.0mm Element Spacing
Single Differential Sensor, 0.5mm Element Spacing
Dual Differential Sensor, 1.0mm Element Spacing,
0.5mm Phase Shift
Dual Differential Sensor, 0.5mm Element Spacing,
0.25mm Phase Shift
Digital Output Differential Sensor, 1.0mm Element
Spacing
Digital Output Differential Sensor, 0.5mm Element
Spacing
Digital Output Signal Processing IC for ABL Sensors
M8 Round PCB, for mounting ABL Sensor
M10 Round PCB, for mounting AKL Sensor
Long, Narrow PCB for Mounting ABL Sensor Parallel to
Long axis
Long, Narrow PCB for Mounting ABL Sensor
Perpendicular to Long axis
PCB for Mounting 2 DD001-12 ICs
Long, Narrow PCB for Mounting AKL Sensor
Perpendicular to Long axis
Long, Narrow PCB for Mounting AKL Sensor Parallel to
Long axis
Long, Narrow PCB for Mounting ABL Sensors Parallel to
Long axis, and 1 or 2 DD001-12 ICs
Long, Narrow PCB for Mounting ABL Sensors
Perpendicular to Long axis, and 1 or 2 DD001-12 ICs
6mm Diameter X 4mm Thick Round Ferrite Magnets
3.5mm Diameter X 4mm Thick Round Ferrite Magnets
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Application Notes
Application Notes for GMR Sensors
Contact Information
NVE Information line: (800) 467-7141
Specific Product or Company Information:
(952) 996-1605 email: [email protected]
Customer Applications Engineering:
(952) 829-9173 email: [email protected]
NVE Internet Home Page: www.nve.com
NVE reserves the right to make product changes and improvements at any time.
The information contained herein is believed to be accurate as of the date of printing, however NVE
assumes no responsibility for its use. Any errors in the technical data printed in this catalog will be
corrected and updated as soon as possible. The most recent copy of this catalog and application notes
will be available online at www.nve.com.
If application questions or concerns exist, please contact NVE prior to use of the products.
- 78 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Application Notes
General Comments
NVE GMR sensors are designed to measure or sense magnetic field strength over a wide range of
fields. GMR sensors directly detect magnetic field rather than the rate of change in magnetic field;
therefore, they are useful as DC field sensors. NVE’s GMR sensors are sensitive to small changes in
magnetic fields. This allows for accurate measurement of position or displacement in linear or
rotational systems. The extremely small size of the sensing element enhances the position sensitivity,
especially in applications incorporating small magnets and large field gradients. Magnetic fields
produced by current carrying conductors make our devices usable as current sensors or detectors.
Competitive Technologies
GMR sensors have greater output than conventional anisotropic magnetoresistive (AMR) sensors or
Hall effect sensors, and are able to operate at fields well above the range of AMR sensors. In addition,
high fields will not “flip” GMR sensors or reverse their output as is possible with AMR sensors. High
fields will also not cause damage to NVE GMR sensors, as is the case with some competing GMR
sensor products.
The output of GMR sensors is frequency insensitive up to 1 MHz. GMR sensors produce an output
with a constant field. This sets them apart from inductive (variable reluctance) field sensors, which
respond only to changes in magnetic field. High resistivity GMR material enables the fabrication of
sensors with high resistance. Sensors with 5 kΩ resistance is standard. Special low power devices can
be manufactured with 30 kΩ or higher resistance. Sensors can also be fabricated with built-in offset at
zero field that provide for a zero crossing in output at a specified field value.
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Application Notes
GMR Material Physics
The giant magnetoresistive phenomenon, discovered in 1988, is an effect found in metallic thin films
consisting of magnetic layers a few nanometers thick separated by equally thin nonmagnetic layers.
Researchers observed a large decrease in the resistance with a magnetic field applied to the films. This
effect is based partly on the increasing resistivity of conductors as their thickness decreases to a few
atomic layers. In bulk material form, conduction electrons in these materials can travel a long distance
before “scattering,” or changing direction, due to a collision with another atomic particle. The average
length that the electron travels before being scattered is called the mean free path length. However, in
materials that are very thin, an electron cannot travel the maximum mean free path length; it is more
likely that the electron will reach the boundary of the material and scatter there, rather than scatter off
another atomic particle. This results in a lower mean free path length for very thin materials. It is
therefore more difficult for conduction electrons to travel in this material, and the result is higher
electrical resistivity. The chart below shows the relationship between resistivity of a magnetic material
such as iron or nickel, and the thickness of the material at very small dimensions. For purposes of
scale, one nanometer equals ten Angstroms; a copper atom has a diameter of about 3 Angstroms:
Resistivity
Resistance of the Material Decreases
as the Mean Free Path Length of
an Electron traveling in the material increases
50
100
150
Mean Free Path Length of an Electron (Angstroms)
In order to take advantage of this effect, GMR films are manufactured with very thin layers of
alternating magnetic and non-magnetic materials. This is done to allow magnetic modulation of the
electron spin in the materials. The spin dependence of conduction electrons in magnetic materials,
along with the increasing resistivity at very small material thicknesses, combine to make the GMR
effect possible.
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Application Notes
The figure below shows a simplified structure of a typical GMR sensor film, as manufactured by NVE:
Cross Sectional Structure of Basic GMR Material
Top Film (Magnetic Material, 20-50 Angstroms Thick)
Conductive Interlayer (Non-Magnetic Material, 15-40 Angstroms Thick)
Bottom Film (Magnetic Material, 20-50 Angstroms Thick)
The diagram shows two magnetic material layers, sandwiching a non-magnetic interlayer. The
magnetic layers are designed to have anti-ferromagnetic coupling. This means that the magnetization
of these layers is opposite to each other when there is no external magnetic field applied to the
material. Antiferromagnetic coupling can be visualized by imagining two bar magnets on either side of
a thin sheet of plastic. The magnets couple head to tail (north pole to south pole) across the boundary
formed by the plastic. In a similar fashion, the magnetization direction of the magnetic layers in the
GMR film couple head to tail across the non-magnetic interlayer of the film.
The conduction electrons in magnetic materials have a spin characteristic. The electrons are normally
referred to as spin up electrons when the material is magnetized in one direction, and spin down
electrons when the material is magnetized in the opposite direction.
The diagram below shows some electron paths inside the GMR material structure. The two arrows
indicate the antiferromagnetic coupling. Notice that the electrons tend to scatter off the two GMR
material interfaces. This is because the electrons from the spin up layer are trying to enter the spin
down layer, and vice versa. Because of the differences in the electron spins, it is more likely that the
electrons will scatter at these interfaces:
Spin UP Electrons Scatter at Interface with Spin DOWN Layer;
Spin DOWN Electrons Scatter at Interface with Spin UP Layer
Average Mean Free Path of the Electrons is Short
Magnetization Direction of Top Film
Top Film
(Primarily Spin UP Electrons,
Due to Magnetization Direction)
Conductive Interlayer
Bottom Film
(Primarily Spin DOWN Electrons,
Due to Magnetization Direction)
Magnetization Direction of Bottom Film
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Application Notes
The end result in this case is that the mean free path length of the conduction electrons is fairly short,
resulting in a relatively high electrical resistance.
If an external magnetic field of sufficient magnitude is applied to this GMR material, it will overcome
the antiferromagnet coupling of the magnetizations between the two magnetic layers. At this point all
the electrons in both films will have the same spin. It will then become easier for the electrons two
move between the layers:
Spin States of the Magnetic Layers are the same;
Electrons Travel More Readily Through Entire Stack of GMR Material.
Average Mean Free Path of the Electrons is Long
External Magnetic Field Aligns
the Magnetization Directions of
Top and Bottom Films
Magnetization Direction of Top Film
Top Film
(Primarily Spin DOWN Electrons,
Due to Magnetization Direction)
Conductive Interlayer
Bottom Film
(Primarily Spin DOWN Electrons,
Due to Magnetization Direction)
Magnetization Direction of Bottom Film
Note that the mean free path length of the electrons has now increased. This results in an overall lower
electrical resistance for the GMR material. The change in resistivity of the material is shown on the
path length diagram below:
Resistivity Plot Showing Operate Points of GMR Material
With and Without an External Magnetic Field Applied;
Applying the External Field Results in Lower Device Resistance
Operate Point of Film,
No External Field Applied
Resistivity
Operate Point of Film
with External Field Applied
50
100
150
Mean Free Path Length of an Electron (Angstroms)
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Application Notes
This change in resistance is the GMR effect.
The size of the resistance decrease is typically 4% to over 20%, depending on the material structure of
the GMR films. Most of NVE’s sensor products rely on a GMR material which exhibits 14% to 16%
decrease in resistance. The “percent GMR” of a given material is calculated using the following
formula:
% GMR = Change in Resistance / Minimum Resistance
For example, assume an electrical resistor is implemented with GMR material, and it shows a nominal
resistance of 5000 Ohms. Then a magnetic field is applied and with this field a minimum resistance of
4400 Ohms is achieved. The percent GMR is then 600/4400, or about 13.6%.
Not all GMR materials operate in the manner described above. All GMR materials rely on modulating
the difference between the magnetization directions of adjacent layers in the GMR film structure, but
some achieve this modulation in different ways. The other most common type of GMR material is
referred to as a “spin valve” GMR material. This type of material does not necessarily rely on antiferromagnetic coupling of the adjacent magnetic layers in the GMR film. In this case one of the
magnetic layers is “pinned,” or fixed with respect to its magnetization direction. The magnetization
direction of the pinned layer will not move when exposed to normal operating magnetic fields.
Therefore, the externally applied magnetic field will modulate the direction of the other magnetic
layer, referred to as the “free” layer. As the angle between the free layer and the pinned layer varies,
the mean free path length of the electrons in the GMR film also varies, and therefore the electrical
resistance will change.
Fixing the magnetization direction of the pinned layer in spin valve GMR materials can be done in a
variety of ways. However, it is important that the layer is pinned in a robust manner; otherwise, the
pinning can be undone by application of a large magnetic field. This will destroy the operation of the
sensor. NVE uses the application of large magnetic fields and high anneal temperatures (over 240°C)
to set the pinned layer of the film. This layer cannot be unpinned with the application of any magnetic
field in the normal temperature range of operation. Therefore, the sensor cannot be damaged by large
magnetic fields. This is also true of NVE’s other GMR sensors; no damage to any NVE GMR sensor
product can result due to the application of extremely large magnetic fields.
One of NVE’s competitors in Europe introduced a GMR sensor in 1997 that could be damaged by
magnetic fields in the 250 Gauss range. This product has since been discontinued.
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Application Notes
GMR Materials Types Manufactured by NVE
NVE manufactures four different types of GMR materials for use in our sensor products. These GMR
materials are described below:
Standard Multilayer (ML) – This GMR material has AF (antiferromagnet) coupling, % GMR in the
range of 12% to 16%, magnetic saturation fields of about 300 Oersteds, stable temperature
characteristics for operation up to 150°C, and moderate hysteresis.
High Temperature Multilayer (HTM) – This GMR material has AF coupling, % GMR in the 8% 10% range, magnetic saturation fields of about 80 Oersteds, stable temperature characteristics for
operation up to 200°C, and high hysteresis.
Low Hysteresis High Temperature Multilayer (LHHTM) – This GMR material is AF coupled, has
% GMR in the range of 8% - 10%, magnetic saturation fields of about 180 Oersteds, stable
temperature characteristics for operation up to 200°C, and low hysteresis.
Spin Valve (SV) – This GMR material has one pinned layer, has % GMR in the range of 4% - 5%,
magnetic saturation fields of about 25 Oersteds, stable temperature characteristics for operation up
to 200°C, and nearly zero hysteresis when operated in saturation mode.
The following table gives a brief comparison of these different GMR materials, and indicates in which
product prefix they are used:
GMR
Material
% GMR
Saturation
Field (Oe)
Temperature
Range
Hysteresis
ML
12%-16%
250 - 450
-40 - +150
Medium
AA, AB,
AD
HTM
8%-10%
60 - 100
-40 - +200
High
AAH, ABH,
ADH
LHHTM
8%-10%
160 - 200
-40 - +200
Low
ABL
SV
4%-5%
20-30
-40 - +200
Low
AAV
Product
Prefixes
In addition to these materials, NVE is currently developing more specialized GMR materials for
various sensor applications, including a bipolar output low hysteresis material and a spin dependent
tunneling material. Please check our web site for new product releases based on these new GMR
materials.
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Application Notes
Temperature Characteristics of GMR Sensors
Temperature excursions cause several changes to the characteristics of GMR sensors. The changes are
described below:
1.
Changes to base resistance of the sensor element [TCR] – This is a temperature coefficient of
resistance of the sensor element with no applied magnetic field to the sensor. The TCR is
normally given in %/ºC.
2.
Changes to the % GMR of the sensor element [TCGMR] – When a magnetic field is applied,
the % GMR exhibited by the sensor element will change. Generally as temperature increases,
% GMR decreases. TCGMR is normally given in %/ºC.
3.
Changes to the saturation field of the sensor element [TCHsat] – The magnetic field at which
the sensor will provide its maximum output will also change with temperature. The saturation
field (Hsat) will decrease as temperature increases. TCHsat is normally given in %/ºC.
For purposes of temperature compensation, a single resistor sensor element made from GMR material
can be modeled as two resistors in series. The first resistor is the base resistive element, and is a
constant resistance at a given temperature, regardless of the applied magnetic field. The second resistor
represents the changing resistance of the single resistor sensor element made from GMR material, as
magnetic field is applied. This model is shown in the following diagram:
R1
R2
Base
Resistance
GMR
Resistance
The base resistance of R1 is the resistance of the sensor element at 25°C when the saturating magnetic
field is applied and R2 has dropped to 0 resistance; in other words, the minimum resistance of the
sensor element as described in the GMR Material Physics section. The following formula can be used
to compute R1 at various temperatures:
R1 = R1 Base Resistance * [ 1 + (TCR * (Temperature - 25°C))]
The resistance of R2 in the diagram varies both with the temperature and the applied magnetic field.
The base resistance of R2 is defined as its maximum resistance at 25°C. This is the resistance with zero
applied magnetic field. The base resistance of R2 will vary with temperature (at zero applied field) as
described by the following formula:
R2Zero Field = R2 Base Resistance * [ 1 + (TCGMR * (Temperature - 25°C))]
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Application Notes
When a magnetic field is applied to R2, its resistance will vary in a generally linear fashion with the
applied field, from zero up to the saturation field (Hsat). After the GMR material’s saturation field is
reached, applying additional magnetic field will not result in changes to the resistance of the device.
The complete equation for R2, taking into account both the changes in % GMR with temperature and
the changes in Hsat with temperature, and assuming operation of the sensor element at magnetic fields
less than the Hsat value, is given below:
R2 = R2Zero Field * [1 - (AF / HsatT)]
Where:
AF = Applied Magnetic Field
HsatT = [email protected]°C * [1 - (TCHsat * (Temperature - 25°C)]
Please note that although the equations provided above result in linear results, the actual GMR devices
are not perfectly linear. In particular, the transition of the output characteristic as it enters magnetic
saturation is rounded, and can be seen in the temperature performance graphs of the various GMR
materials shown at the end of this section. In addition, non-linearities also exist in some cases near the
zero field range of the devices. The best fit for the formulas provided above is in the linear operating
range of each sensor element as defined in the product specifications.
In addition, the effects of flux concentration and shielding in the sensor element are not reflected in
these equations, nor is any effect from hysteresis included.
In many cases, an analysis of the complete temperature characteristic of the device is not required; the
only important parameter is how the output of the sensor device itself changes with temperature. In this
case, it is important to know if the sensor is being supplied with a constant voltage source or a constant
current source. If a constant current source is used, the voltage across the sensor can increase as the
resistance of R1 increases with temperature, thus mitigating some of the signal loss effects with
temperature.
NVE has defined the following two terms to describe the change in signal output with temperature:
TCOV: Temperature Coefficient of the Output with a constant Voltage (V) source; given in %/°C.
TCOI: Temperature Coefficient of the Output with a constant Current (I) source; given in %/°C.
These numbers will provide an accurate indication of the change in the output of the parts over
temperature in the linear operating range. Note that this data is provided for NVE’s AA and AB type
parts but not for any of the parts that include a signal processing IC in the package. This is because
NVE typically builds temperature compensation circuitry into the signal processing IC.
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Application Notes
The following table summarizes the temperature coefficients described in the preceding paragraphs for
the GMR materials used in most of NVE’s products:
GMR Material Type
Product Series
TCR (%/C)
TCGMR (%/C)
TCHsat (%/C)
TCOI (%/C)
TCOV (%/C)
ML
AA, AB, AD
+0.14
-0.10
-0.10
+0.03
-0.10
HTM
AAH, ABH
+0.11
-0.38
-0.45
+0.10
0.0
LHHTM
AAL, ABL, AKL
+0.11
-0.38
-0.25
-0.28
-0.40
The following graphs show the basic temperature behavior of the three most common types of GMR
materials used in NVE’s products. The first graph shows the temperature behavior of an AA002-02
sensor, which is representative of the GMR material used in NVE’s AA, AB, and AD-Series products:
AA002 Temperature Performance ,
1mA Curre nt Supply
0.35
0.3
Output Voltage (V)
0.25
0.2
0.15
-40C
0.1
25C
85C
0.05
125C
0
-20
-15
-10
-5
0
5
10
15
20
-0.05
Applie d Ma gnetic Fie ld (Oe)
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Application Notes
The next graph shows the temperature behavior of an AAH002-02 sensor, which is representative of
the GMR material used in NVE’s AAH and ABH-Series products:
AAH002 Temperature Performance,
2.28mA Current Source
0.4
0.35
0.3
Output Voltage (V)
0.25
0.2
0.15
-40C
0.1
25C
85C
0.05
125C
0
-10
-5
0
5
10
-0.05
Applied Magnetic Field (Oe)
The next graph shows the temperature behavior of an AAL002-02 sensor, which is representative of
the GMR material used in NVE’s AAL, ABL, and AKL-Series products:
AAL002 Temperature Performance,
1mA Current Supply
0.35
0.3
Output Voltage (V)
0.25
0.2
0.15
0.1
-40C
25C
85C
0.05
125C
0
-30
-20
-10
0
10
20
30
-0.05
Applied Magnetic Field (Oe)
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Application Notes
Hysteresis in GMR Sensors
All magnets and magnetic materials (iron, nickel, etc.) have magnetic hysteresis. Hysteresis refers to
the history of the magnetic field applied to the material and how it affects the material properties and
performance. NVE’s GMR sensors are made of magnetic materials, so they are subject to hysteresis
effects.
Hysteresis can make GMR sensors easier or harder to use, depending on the application. In nearly all
digital applications, hysteresis is desirable because it prevents “jitter” at the sensor operate point. With
sensor elements that do not have hysteresis, electrical hysteresis is normally built into the signal
processing electronics.
In a linear application, hysteresis can be problematic, but this depends on the application. For example,
if a GMR sensor is used as a current sensor, and it is detecting the magnetic field from a repetitive
current such as a sinusoidal waveform, then the recent magnetic history at sensor will always be the
same. This will result in repeatable output from the sensor at each current level. In this case, hysteresis
is not an issue. Another important point is that time is not a factor, only the magnitude of the fields that
the sensor is exposed to. For example, if the frequency of the current’s sinusoidal waveform changes,
or if the current stops at a given level for some period of time, and then restarts in the same sinusoidal
pattern, there will be no hysteresis effects at the sensor.
On the other hand, if the magnetic field to be detected is not repetitive in magnitude, but more random
in nature, then an error can result in the sensor output reading. The size of this error will depend on the
amount of hysteresis in the sensor element and the difference in the polarity and magnitudes of the
applied fields that the sensor was recently exposed to. The error will take the form of a voltage offset
change in the sensor element.
Because the error is essentially an offset change, it can be eliminated in cases where the signal is high
in frequency by AC coupling the output of the sensor to an amplifier. This is a common solution in
applications such as currency detection where a very small signal that can be random in nature must be
detected from a moving object. AC coupling and a high gain amplifier are employed to see this small
signal with GMR sensors.
If DC coupling the sensor to an amplifier or output stage is required, and the magnetic field will not be
repeatable, then the hysteresis in the sensor element must be taken into account as a potential error in
the reading. For NVE’s AA-Series sensors, this potential error can be as high as 4% if the sensor is
exposed to one polarity of magnetic field (unipolar mode of operation), and as high as 20% if the
sensor is exposed to a bipolar field. However, even in these cases the large output signal of the GMR
sensor elements can provide advantages over other technologies.
The polarity of the magnetic field that is applied to the sensor has a strong effect on the amount of
hysteresis. Unipolar operation is when the applied magnetic field at the sensor is always in the same
polarity, or direction. Bipolar operation is when the magnetic field at the sensor changes direction.
Hysteresis is much more exaggerated in the sensor element when a bipolar magnetic field is applied to
the sensor.
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Application Notes
The following chart shows the output of an AA-Series sensor when it is exposed to a saturating
unipolar field:
Voltage
Output
Output Follows This
Curve from Positive
Saturation Field Back
to Zero
Output Follows This
Curve from Zero to
Positive Saturation
Field
- Applied Field
+ Applied Field
In the case of a unipolar field, the sensor is operating on the minor hysteresis loop. The hysteresis in
this case is relatively small.
The following chart shows the output of the same sensor when it is exposed to a saturating bipolar
field:
Output Follows This
Curve from Negative
Saturation Field Back
to Zero
Output Follows This
Curve from Positive
Saturation Field Back
to Zero
Voltage
Output
Output Follows This
Curve from Zero to
Positive Saturation
Field
Output Follows This
Curve from Zero to
Negative Saturation
Field
- Applied Field
+ Applied Field
In this case the sensor is operating on the major hysteresis loop, so the hysteresis shown by the output
characteristic of the sensor is relatively large. This is the worst-case hysteresis exhibited by the sensor
element.
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Application Notes
After-saturation effects are important in understanding how the sensor behaves. It is important to note
that after the sensor is saturated by a magnetic field, either in the positive or negative direction, it
returns to zero field along the inside curve of the major loop characteristic. As shown in the diagram
below, a negative saturating field applied to the sensor, followed by a small positive field, will result in
a negative voltage output:
After Negative
Saturation
Field, Sensor Returns
to Zero Along This Line
Voltage
Output
After returning to zero,
a small positive field will
cause the output voltage
to go negative
- Applied Field
+ Applied Field
The same small positive field, applied after a positive saturating field, will result in a positive voltage
output:
Voltage
Output
After Positive
Saturation
Field, Sensor Returns
to Zero Along This Line
After returning to zero,
a small positive field will
cause the output voltage
to go positive
- Applied Field
+ Applied Field
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Application Notes
This confusing result is often seen when trying to detect very small magnetic fields such as the earth’s
field in magnetic compass applications or currency detection applications. The solution to this problem
is to bias the sensor element with an external magnetic field, so that the operating point of the sensor is
on the linear portion of the characteristic curve. This can be done either with an external permanent
magnet, or a current running near the sensor. Biasing the sensor with a positive external field from a
magnet or current will shift the sensor’s output characteristic as shown below:
Voltage
Output
- Applied Field
+ Applied Field
With this approach, a small applied field to the sensor will result in a bipolar output signal.
Furthermore, the slope of the signal characteristic will be the same no matter which curve the sensor is
operating on. So, the magnetic sensitivity of the device is the same, no matter how much hysteresis the
sensor has.
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Application Notes
Also important to note regarding hysteresis is that it scales with the applied magnetic field. For
applications where the magnetic field variations are small, hysteresis is small. The following diagram
illustrates this point:
Voltage
Output
Output Follows This
Curve from Positive
Saturation Field Back
to Zero
Output Follows This
Curve from Zero to
Positive Saturation
Field
- Applied Field
+ Applied Field
The enlarged area on the left shows the outer boundaries of the sensor hysteresis loop when it is
operated in unipolar mode (positive magnetic fields only). Inside the outer boundaries is the sensor
behavior if it is exposed to small but increasing magnetic fields. For example, if this was the
characteristic of an AA002-02 sensor, the magnetic field history for the characteristic between the
boundaries might start at 6 Gauss, then go to 6.5, then 5.5, then 7, then 7.5, and so forth. The curvature
of the lines between the boundaries is exaggerated for clarity. The diagram shows that for small
variations of the magnetic field, the hysteresis is also small, and as the variations in field increase, so
does the hysteresis.
Sensor hysteresis presents challenges in some applications, but in most cases the sensor elements can
be used to advantage despite the hysteresis characteristics.
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Application Notes
GMR Magnetic Field Sensors (Magnetometers)
The NVE standard line of magnetic field sensors use a unique configuration employing a Wheatstone
bridge of resistors and various forms of flux shields and concentrators. Using magnetic materials for
shielding eliminates the need for a bias field with GMR sensors. NVE has developed a process to
plates a thick layer of magnetic material on the sensor substrate. This layer forms a shield over the
GMR resistors underneath, essentially conducting any applied magnetic field away from the shielded
resistors. The configuration allows two resistors (opposite legs of the bridge) to be exposed to the
magnetic field. The other two resistors are located under the plated magnetic material, effectively
shielding them from the external applied magnetic field. When the external field is applied, the
exposed resistors decrease in electrical resistance while the other resistor pair remain unchanged,
causing a signal output at the bridge terminals.
The plating process developed by NVE for use in GMR sensor applications has another benefit: it
allows flux concentrators to be deposited on the substrate. These flux concentrators increase the
sensitivity of the raw GMR material by a factor of 2 to 100. The flux concentration factor is roughly
equivalent to the length of one shield divided by the length of the gap. This allows use of GMR
materials that saturate at higher fields. For example, to sense a field from 0 to 100 Oersteds, NVE
deposits a GMR sensor that saturates at a nominal 300 Oersteds and flux concentrators with a
magnification factor of three. The figure below shows the basic layout of the device:
Axis of sensitivity
Silicon substrate
(1300 µm x 400 µm)
Flux concentrator (2)
Metal interconnects
Gap
Magnetically shielded resistor (2)
Bonding pads (4)
(100µm x 100µm)
Magnetically active resistor pair
TYPICAL GMR MAGNETIC FIELD SENSOR LAYOUT
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Application Notes
The magnetic characteristic of a shielded bridge device is shown below. This characteristic was taken
from an actual production device with 5V supplied to the bridge power terminals (5 kΩ bridge).
AA002-02 Se nsor Characte ristic, 5V Supply
0.3
0.25
Voltage Output
0.2
0.15
0.1
0.05
0
-20
-15
-10
-5
0
5
10
15
20
Applied Field (Oe)
GMR MAGNETIC FIELD SENSOR OUTPUT CHARACTERISTIC
This signal output can be coupled directly into a linear amplifier or a comparator to generate a high
level electrical signal proportional to the strength of the magnetic field seen by the sensor.
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Application Notes
GMR Magnetic Gradient Sensors (Gradiometers)
The NVE gradiometer is a GMR magnetic field sensor used to detect field gradients between
Wheatstone bridge configured resistors. This device is “unshielded” (i.e., it does not employ resistor
shields) therefore all four (4) legs of the Wheatstone bridge are active (they respond to changes in field
level). Gradiometers can be used to detect either magnetic or ferrous targets. To detect gradient
changes caused by the proximity to a moving ferrous target, a biasing magnet is required. Refer to the
Magnetic Biasing section and the GT Sensor application notes for gradiometer biasing guidelines.
The output of the gradiometer differs from that of a standard GMR Magnetic Field Sensor. The
gradiometer’s output can be bipolar versus unipolar and can be shaped by the use of magnetic biasing
and the application of external flux shaping devices (flux guides). The figure below shows an example
design:
Axis of sensitivity
Silicon substrate
(1250 µm x 650 µm)
Bonding pads (4)
(100µm x 100µm)
Active resistor pairs
Metal interconnects
Unused resistor pairs
(different resistor spacing may be
incorporated based on application)
BASIC GRADIOMETER BRIDGE SENSOR LAYOUT
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Application Notes
The following graph shows the output characteristic from a gradiometer as the field gradient is varied
across the sensor IC:
Typical Gradiometer Transfer Function
Differential Voltage Out of Sensor (mV)
50
40
30
20
Increasing field
on X resistors
10
0
-400Increasing -200
field
on Y resistors
-10
0
200
400
-20
-30
-40
-50
Magnetic Field Applied to Resistors
GRADIOMETER BRIDGE SENSOR OUTPUT CHARACTERISTIC
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Application Notes
Magnetic Reference Information
Permanent Magnets
The Magnetic Materials Producers Association (MMPA) publishes two reference booklets with
valuable reference information on basic magnetic theory, permanent magnet materials and their
practical application. They are:
MMPA Standard no. 0100-96
Standard Specifications for Permanent Magnet Materials
MMPA PMG-88
Permanent Magnet Guidelines
These booklets can be obtained from the MMPA:
Magnetic Materials Producers Association
8 South Michigan Ave., Suite 1000
Chicago, IL 60603
(312) 456-5590
(312) 580-0165 (fax)
Measurement Systems
Unit
Symbol
cgs System
SI System
English System
Length
L
centimeter (cm)
meter (m)
inch (in)
Flux
φ
maxwell
weber (Wb)
maxwell
Flux density
B
gauss (G)
tesla (T)
lines/in
Magnetizing force
H
oersted (Oe)
ampere turns/m (At/m)
ampere turns/in (At/in)
Magnetomotive force
F
gilbert (Gb)
ampere turn (At)
ampere turn (At)
Permeability in air
µ0
1
4π x 10
-7
2
3.192
Conversion factors for between measurement systems can be found in the appendix to this catalog.
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Application Notes
Signal Conditioning Circuits
A number of methods exist for pre-amplification of an NVE GMR bridge sensor output. This section
shows some representative circuits and compares the relative advantages and disadvantages of some
common configurations. The circuits shown were designed for low power and 5V operation. Low
noise or high performance applications should be designed with lower noise, higher performance
components.
Operational Amplifier (Op Amp) Bridge Preamplifier Circuits
Single Op Amp Bridge Amplifier
The figure below shows a simple circuit for amplifying an NVE AAxxx-02 GMR Magnetic Field
Sensor’s bridge output using a single 5V supply. The advantages of this configuration are simplicity,
low component count, and low cost.
+5V
Vref
+5V
C1 0.1uF
C2 0.1uF
R4
R3
3 +
8 Vin+
U1
AAxxx-02
Bridge Sensor
5 Vout+
2 1 Vout-
R1
7 V+
U2
LMC7101A/NS
Vout
6
4 V-
R2
4 Vin-
SINGLE OP AMP PREAMPLIFIER CIRCUIT
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Application Notes
The equation for the amplified voltage is:

 R4  
 R2   R3 + R4 
Vout =  ( Vout + )

 − ( Vout − )   + Vref
 R3  
 R1 + R2   R3 

Assuming R1 + R2 = R3 + R4 >> 5K
This type of amplifier has two significant limitations in that;
1) the feedback resistors load the output of the NVE bridge sense resistors,
and
2) the circuit has a poor common mode rejection (CMRR) if the resistor ratios are not ideally matched.
Users of this circuit should be aware of the deficiencies and ensure that the feedback resistors are large
compared to the bridge resistor values and that the bridge supply is stable and free from noise and
ripple. Any pickup on the bridge leads should be minimized through proper layout, filter capacitors,
and/or shielding.
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Application Notes
Two Op Amp Bridge Amplifier
The two op amp circuit shown below reduces the loading of the preamplifier on the NVE bridge
outputs but still has a CMRR that is dependent on the ratio of resistor matching. The AC CMRR is also
poor in that any delay of the common mode signal through op amp U2 provides a mismatch in the
signals being delivered to op amp U3 for cancellation. Its advantages are simplicity and low cost.
+5V
+5V
C3 0.1uF
C1 0.1uF
3 +
+5V
U1
AAxxx-02
Bridge Sensor
8 Vin+
C2 0.1uF
5 Vout+
1 Vout-
2 3 +
4 Vin2 -
Vref
R4
7 V+
U2
LMC7101A/NS
R1
7 V+
U3
LMC7101A/NS
Vout
6
4 V-
R2
6
4 V-
R3
RG
TWO OP AMP PREAMPLIFIER CIRCUIT
The equation for DC gain of the two op amp circuit (assuming infinite input impedance of the op
amps) is:
  R2   2R2  
 R2   R4 
Vout = Vref + VIN  1 +   + 
  for   =   and VIN = (Vout+) - (Vout-)
 R1   R3 
  R1   RG  
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Application Notes
Three Op Amp Bridge Amplifier
The three op-amp circuit shown in the figure below is the most robust version of an op amp
implementation. In this circuit the CMRR still depends on the resistor ratios of the differential
amplifier (U4) but is not dependent on the resistors R1, RG, and R2. Therefore to minimize common
mode errors the gain of the first stage should be made large compared to the gain of the second stage.
The minimum gain of the second stage is dependent on amplifiers U2 and U3 output voltage range and
Op Amp U4’s common-mode input range, which for the LMC7101, is rail-to-rail allowing a gain of
one (1) in the second stage.
+5V
C2 0.1uF
3 +
7 V+
U2
LMC7101A/NS
2 +5V
Vref
6
4 VR6
C1 0.1uF
+5V
C4 0.1uF
R4
R2
RG
U1
AAxxx-02
Bridge Sensor
8 Vin+
C3 0.1uF
5 Vout+
1 Vout-
3 +
+5V
2 3 +
4 Vin-
7 V+
U3
LMC7101A/NS
2 -
7 V+
U4
LMC7101A/NS
Vout
6
4 V-
R3
6
R5
4 V-
R1
THREE OP AMP PREAMPLIFIER CIRCUIT
The DC transfer function of the circuit is:
 2R1  R4 
Vout = Vref +  1 +
   VIN for R1 = R2, R3 = R5, R4 = R6 and VIN=(Vout+) - (Vout-)

RG   R3 
The symmetrical nature of this configuration also allows for cancellation of common mode errors in
amplifiers U2 and U3 if the errors track.
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Application Notes
Instrumentation Amplifier Bridge Preamplifier
The advent of low-cost, high-performance Instrumentation Amplifier (IAs) such as the Analog Devices
AD620 and the Burr Brown INA118 have greatly simplified the design of bridge preamplifiers while
adding significant advantages in noise, size, and performance over op amp implementations. The
figure below shows the design of a bridge amplifier circuit using an INA118 (the Analog Devices
AD620 is pin-for-pin compatible with the INA118).
+5V
+5V
C1 0.1uF
C2 0.1uF
Use for AC
coupling
U1
AAxxx-02
Bridge Sensor
8 Vin+
4 Vin-
7
5 Vout+
2 IN-
R3
C3
3 IN+
1 RG1
RG
C3
1 Vout-
8 RG2
6
U2
INA118/BB
Vout
5 REF
R3
4
-5 V
Vref
INSTRUMENTATION AMPLIFIER PREAMPLIFIER CIRCUIT
The gain of this circuit is:
50K 

V OUT =  1 +
 V IN + V ref

RG 
1
point is given by f =
2πR3 C3
with VIN = (Vout+) - (Vout-) and the frequency 3dB
Integrated circuit instrumentation amplifiers utilize circuit techniques where resistor matching is not as
critical to the CMRR as active device matching. Active device matching can be easily controlled on
integrated circuits allowing for greatly improved CMRR of instrumentation amplifiers over op amp
implementations. Also, the gain-bandwidth product of instrumentation amplifier circuits can be higher
than op amp circuits.
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Application Notes
Threshold Detection Circuit
The figure below shows the implementation of a low power threshold detection circuit that utilizes the
AAxxx-02 GMR Magnetic Field Sensor and the Burr Brown INA118 instrumentation amplifier.
Comparator hysteresis has been added around the LM311 comparator to minimize random triggering
of the circuit on potential noise sources and pickup. The gain of the instrumentation amplifier is the
same as before. The hysteresis of the comparator is approximately:
R1
R2 

Vh ≈ 2.5
−
 Neglecting the finite output swing of the comparator.
 R1 + R2 + R3 R1 + R2 
+5V
+5V
C1 0.1uF
C2 0.1uF
7
U1
AAxxx-02
Bridge Sensor
8 Vin+
2 IN5 Vout+
3 IN+
1 RG1
1 Vout-
8 RG2
RG
6
U2
INA118/BB
5 REF
4 Vin-
4
-5 V
Vref
+5V
R2
C3 0.1uF
R1
R3
2 +
+2.5V
8 V+
U3 IM311
7
1 G
3 4 V-
THRESHOLD DETECTION CIRCUIT
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Vout
Application Notes
Noise In NVE Giant Magnetoresistive Sensors
The 1/f noise characteristic of NVE GMR sensors is approximately an order of magnitude higher than
noise for thin film resistors. The noise has been shown to follow the usual characteristics of being
proportional to the square of the current density. The figure below shows a noise plot of an AA002-02
sensor using various methods for powering the sensor:
100000
AA002-02 Spectrum Analysis 6/10/98
9V Battery
1.616 mA
18V Battery
3.233 mA
479 nA Blue
Box
498 uA Blue
Box
2.003 mA
Blue Box
Log nV/√Hz/Gain
10000
1000
100
10
0.01
0.1
1
10
100
1000
10000
100000
Log Frequency (Hz)
For use in low-field applications, the noise of the NVE GMR sensors limits the minimum signal
detected. For measuring low fields it is recommended that an AC modulation/demodulation scheme be
implemented. The figure below shows a block diagram of an AC modulation/demodulation circuit.
The phase shifter block is required to account for parasitic phase shift around the loop.
PHASE SHIFTER
SINE WAVE
GENERATOR
8 Vin+
+
RG
1 Vout-
RG1
RG2
INST AMP
-
4 Vin-
IN1
DEMODULATOR
U1
AAXXX-02
BRIDGE SENSOR
IN2
5 Vout+
Vout
OUT
Rf
Cf
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Application Notes
Use Of GMR Magnetic Field Sensors
General Considerations
All of NVE’s GMR Magnetic Field sensors have a primary axis of sensitivity. The figure below shows
an AAxxx-02 Series GMR Magnetic Field Sensor with a cut away view of the die orientation (not to
scale) within an SOIC8 package.
Flux Concentrators
Axis of Sensitivity
SENSITIVE MAGNETIC AXIS – AA00X-02 SENSOR
The flux concentrators on the sensor die gather the magnetic flux along the axis shown and focus it at
the GMR bridge resistors in the center of the die. The sensor will have the largest output signal when
the magnetic field of interest is parallel to the flux concentrator axis. For this reason, care should be
taken when positioning the sensor to optimize performance. Although sensor position tolerance may
not be critical in gross field measurement, small positional variation can introduce undesirable output
signal errors in certain applications.
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Application Notes
Magnetic Biasing
In many applications, GMR Magnetic Field Sensors make use of biasing magnetic fields. Biasing
magnetic fields provide either a magnetic field to sense (where one is not present) or create a pseudo
zero field. Back-biasing a sensor consists of applying a magnetic field through the sensor package
without influencing the sensor. The purpose is to create a magnetic field that the device can sense for
applications where no magnetic field is present such as ferrous material detection. The figure below
shows a permanent magnet used for this purpose. The magnet adjusted in the X direction, as shown,
achieves the maximum field in the Z direction and minimum field in the sensitive X direction.
Z
N
S
X
MAGNETIC BIASING CONFIGURATION
Another means of biasing a GMR Magnetic Field Sensor is to provide a constant magnetic field in the
sensitive direction. The result is a sensor biased part way up its output curve shown in the figure
below.
AA002 with Negative Bias Field Applied
0.3
0.25
Voltage Output
0.2
0.15
0.1
0.05
0
-30
-20
-10
0
10
20
-0.05
Applie d Fie ld (Oe)
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Application Notes
This biasing technique creates a bipolar output with a DC offset. Another typical purpose for this kind
of biasing is to bias the sensor away from the zero field area, where hysteresis is more pronounced.
Since gradiometers respond to the flux gradient rather than the field itself, they can be biased to zero
offset to work in a gear tooth sensing application. It is important not to bias a gradiometer to a high
enough field to saturate the GMR resistors.
More information on biasing gradiometers for gear tooth sensor applications is found in the GT Sensor
application notes section.
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Application Notes
Application Notes for GT Sensors
General Theory of Operation of Differential Sensors (Gradiometers)
Differential sensors, or gradiometers, provide an output signal by sensing the gradient of the magnetic
field across the sensor IC. For example, a typical GMR sensor of this type will have four resistive
sensor elements on the IC, two on the left side of the IC, and two on the right. These resistive sensor
elements will be wired together in a Wheatstone bridge configuration. When a magnetic field
approaches the sensor IC from the right, the right two resistive sensor elements will decrease in
resistance before the elements on the left. This leads to an imbalance condition in the bridge, providing
a signal output from the bridge terminals.
R1 and R2 see a Larger Field than R3 and R4
R3
R4
R1
R1
Out-
Out+
GT Sensor
R4
R2
Field Decreases as Distance from Source Increases
R2
R3
Point
Source
of
Magnetic
Field
Note that if a uniform magnetic field is applied to the sensor IC, all the resistive sensor elements will
change at the same time and the same amount, thus leading to no signal output from the bridge
terminals. Therefore, a differential sensor cannot be used as a magnetometer or an absolute field
detector; it must be used to detect the presence of a magnetic gradient field.
Gradient fields are present at the edge of magnetic encoders and magnetically biased gear teeth. As a
result, differential sensor elements are ideally suited for speed and position detection in these
applications.
GT Sensor Operation with Permanent Magnet Bias
Magnetic encoders generate their own magnetic field, but a gear tooth wheel does not, so if a
differential sensor is to be used to detect gear teeth, a permanent magnet is required to generate a
magnetic bias field. The differential magnetic sensor will then be used to detect variations in the field
of the permanent magnet as the gear tooth passes by in close proximity.
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Application Notes
The following series of drawings shows a biased GT Sensor. The drawings show how the magnetic
field generated by the bias magnet is influenced by the moving gear tooth, and how the output signal
appears at four equally spaced positions between adjacent gear teeth:
Direction of Sensitivity
GMR Sensor
Resistors R3, R4
Magnet
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
GMR Sensor
Resistors R3, R4
Magnet
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
GMR Sensor
Resistors R3, R4
Magnet
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
GMR Sensor
Resistors R3,
R4
Magnet
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
Despite the simplicity of the preceding drawings, magnetically biasing a gear tooth for a production
product can be complex. Typically, the position of the sensor relative to the magnet is fixed, but there
is a variation in the airgap between the sensor and the target gear tooth. This can lead to magnetic
conditions that can cause an unstable output.
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Application Notes
For example, tolerances on the placement of the magnet relative to the sensor are not perfect, and any
slight variation in the placement of the magnet can lead to offset problems; see the drawing below:
Direction of Sensitivity
Voltage Output of
GMR Bridge
Magnet
GMR Sensor
Resistors R3, R4
GMR Sensor
Resistors R1, R2
Rotation
Offset Induced by
Asymmetry of Magnet
and Sensor Elements
Generally the magnet is glued in place; this can lead to tilting of the magnet with respect to the sensor,
introducing more variations in the field at the sensor, and more offset problems, as well as potential
glue joint problems. Furthermore, the composition of most inexpensive magnets is not particularly
uniform, and many have cracks or other mechanical imperfections on the surface or internally that lead
to a non-uniform field. Most permanent magnets have a temperature coefficient, and some can lose up
to 50% of their room temperature strength at 125°C. The following drawing shows the effects of
temperature added onto an imperfect bias. The offset of the sensor varies with temperature as shown:
Direction of Sensitivity
GMR Sensor
Resistors R3, R4
Magnet
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
25C
25C
125 C
125 C
Rotation
Finally, as the airgap changes, the magnetic field at the sensor also changes. So, the magnetic field at
the sensor will vary from one installation to the next, and if the gear has runout, wobble, or expands
with temperature, the output signal and offset of the sensor element will vary.
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Application Notes
As a solution to these potential problems, NVE’s AKL-Series GT Sensors offer internal signal
processing which compensates for temperature variation, sensor output variation, and magnet/target
variation. This results in a stable digital output signal with wide tolerance for magnet placement and
quality. For analog applications, NVE offers the following guidelines for biasing GT Sensors with
permanent magnets:
1.
NVE recommends about 1.5 mm distance from the back of the sensor to the face of the
magnet, in order to keep the flux lines at the sensor element “flexible” and able to follow the
gear teeth with relative freedom. This distance can be achieved by putting the sensor on one
side of a circuit board, and the magnet on the other.
2.
To fix the position of the magnet on the circuit board more precisely, the board can be made
thicker, and a pocket can be machined into it to hold the magnet. This service is readily
available from most circuit board manufacturers.
3.
Various high temperature epoxies can be used to glue the magnet in position; NVE
recommends 3M products for this purpose.
4.
If zero speed operation is not required, AC coupling the sensor to any amplifier circuitry will
remove the offset induced in the sensor by the magnet.
5.
If zero speed operation is required, some method of zeroing the magnet-induced offset voltage
from the sensor will be required for maximum airgap performance. NVE’s AKL-Series
sensors have this feature built in, and NVE’s DD001-12 signal conditioning IC also includes
this feature.
6.
GT Sensor ICs are centered in the plastic package, so placement of the permanent magnet
should be symmetrical with the package.
7.
Ceramic 8 magnets are a popular choice in this application, and provide good field
characteristics and low cost. However, C8 magnets lose substantial magnetic strength at
higher temperatures. For analog output applications where a consistent signal size over
temperature is desirable, use of an Alnico 8 magnet (the most temperature stable magnet) is
recommended. Samarium-Cobalt magnets and Neodymium-Iron-Boron magnets are not
recommended because they are so strong that they tend to saturate the GMR sensor element.
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Application Notes
GT Sensor Operation with Magnetic Encoders
Magnetic encoders generate their own magnetic field, so they are much easier to work with than gear
tooth wheels, as no bias magnet is required for the sensor. Also, magnetic encoders have alternating
north and south magnetic poles on their faces. Therefore the magnetic field is generated by the moving
body, and sensor offset problems are greatly reduced. The following drawing shows a GT Sensor
response to a magnetic encoder:
Direction of Sensitivity
GMR Sensor
Resistors R3, R4
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
S
N
S
N
GMR Sensor
Resistors R3, R4
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
S
N
S
N
GMR Sensor
Resistors R3, R4
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
S
N
S
N
GMR Sensor
Resistors R3, R4
GMR Sensor
Resistors R1, R2
Voltage Output of
GMR Bridge
Rotation
S
N
S
N
Note that in this case, as long as the sensor is positioned symmetrically with the encoder, offset is
minimized. Also note that the GT Sensor provides one full sine wave output for each magnetic pole.
This is double the frequency of a Hall effect sensor, which provides one full sine wave output for each
north-south pole pair. As a result, replacing a Hall sensor with a GT sensor doubles the resolution of
the output signal.
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Application Notes
NVE offers the following guidelines for using GT Sensors in magnetic encoder applications:
1.
Position the sensor as symmetrically as possible with the encoder to minimize offset
problems.
2.
AC couple the sensor to an amplifier to eliminate any offset issues if zero speed operation is
not required.
3.
If zero speed operation is required, NVE’s AKL-Series and DD-Series parts automatically
compensate for offset variations and provide a digital output signal.
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Application Notes
Application Circuits
Signal processing circuitry for analog output sensors, such as NVE’s ABL-Series products, varies
widely in cost, complexity, and capability. Depending on user requirements, a single op amp design
may be sufficient. For low signal level detection, a low noise instrumentation amp may be desirable.
For complete control of all parameters, use of a complete signal processing IC which can tailor gain,
offset calibration, and temperature compensation may be required. Please see NVE’s Engineering and
Application Notes bulletin for further details on the various approaches that are available.
For digital output applications, NVE’s AKL-Series and DD-Series products provide the most cost
effective approach. Both of these products provide two-wire, i.e., current modulated output signals. For
many applications, an open collector or digital voltage output signal is desirable. The following two
circuits convert a two-wire current modulated signal into an open collector or digital voltage output
signal:
VCC
AKL00x Sensor
or DD001 IC
Ground
Open Collector
(Current Sink)
Output
+
VCC
-
100 Ohm
Vref (0.7V)
VCC
+
VCC
-
AKL00x
Sor DD001 IC
Ground
Comparator
Digital
Voltage
Output
100 Ohm
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Application Notes
Measuring Displacement
Basic concepts
Because of their high sensitivity, GMR Magnetic Field Sensors can effectively provide positional
information of actuating components in machinery, proximity detectors, and linear position
transducers. The figures below illustrate two simple sensor/permanent magnet configurations used to
measure linear displacement. In the first diagram, displacement along the y-axis varies the Bx field
magnitude detected by the sensor that has its sensitive plane lying along the x-axis. The second
diagram has the direction of displacement and the sensitive plane along the x-axis.
N
S
y
X (axis of sensitivity)
N
S
y
X (axis of sensitivity)
Application examples
•
•
•
•
•
•
Hydraulic/pneumatic pressure cylinder stroke position
Suspension position
Fluid level
Machine tool slide position
Aircraft control-surface position
Vehicle detection
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Application Notes
Current Measurement
Basic concepts
GMR Magnetic Field Sensors can effectively sense the magnetic field generated by a current. The
figure below illustrates the sensor package orientation for detecting the field from a current-carrying
wire. This application allows for current measurement without breaking or interfering with the circuit
of interest. The wire can be located above or below the chip, as long as it is oriented perpendicular to
the sensitive axis.
Axis of
sensitivity
Direction of
current flow
SENSING MAGNETIC FIELD FROM A CURRENT-CARRYING WIRE
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Application Notes
The figure below shows another configuration where a current trace on a PCB is under the boardmounted sensor.
NVE
AAxxx-xx
Axis of Sensitivity
Current carrying
PCB trace
PCB
SENSING MAGNETIC FIELD FROM A CURRENT CARRYING PCB TRACE
An Excel spreadsheet is available on NVE’s web site which helps calculate the magnetic field at the
sensor from a current carrying trace on the board as shown in the diagram above.
Principles of Operation
The magnetic field created by the current surrounds the conductor radially. As the magnetic field
affects the GMR material in the sensor, a differential output is produced at the out pins of the sensor.
The magnetic field strength is directly proportional to the current flowing through the conductor. As
the current increases, the surrounding magnetic field will also increase, thus increasing the output from
the sensor. Similarly, as the current decreases, the magnetic field and sensor output decrease.
Since the current is not measured directly, the sensor output must be correlated to the current. The
following data and graphs are based upon analysis of NVE’s evaluation board contained in our current
sensor evaluation kit, part number AG003-01. The PCB contains four traces of three different widths:
90 mils, 60 mils, and 10 mils.
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Application Notes
DATA ANALYSIS- One To Ten Amps
Currents (1-10 A) were run through the 90 and 60-mil traces found on the PCB in NVE’s Current
Sensor Evaluation Kit AG003-01. An AA003-02 sensor was placed over the 90 and 60-mil traces and
different levels of DC current were run through the traces. This current and the corresponding output
from the sensors are shown in the following graphs.
AA003-02 over 0.090" wide,
0.0023" thick trace
450
400
Output (mV)
350
300
250
200
150
100
50
mV Out = 29.8 ± 0.2A
@8.33V
0
0
2
4
6
8
10
Current(A)
The sensor was supplied with 8.33V and was hand-soldered over the trace. The trace is 0.090” wide
and 0.0023 ± 0.0002" thick. The marks on the graph are output error bars which cover the expected
error from this part due to intrinsic hysteresis and measurement errors. The current was swept from
zero to ten Amps and back to zero multiple times. The output voltage at specific current levels was
analyzed and an output voltage precision was determined to have a relative error of approximately
±0.7% with errors of up to 2% possible at low currents.
A linear fit on the data above shows a 29.8 ± 0.2 mV/A correlation in this configuration. The sensor
utilizes a Wheatstone bridge and thus the applied voltage across the bridge is directly related to the
output. By dividing the slope by 8.33V, we get a more useful number of 3.57 ± 0.02 mV/V/A. With
this number, the user can determine the expected output for any applied voltage.
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Application Notes
The same analysis was given to a 0.060" wide trace of the same thickness. A voltage of 8.33V was
applied and the resulting graph is shown below.
AA003-02 over 0.060" wide
0.0023" thick trace
350
Output (mV)
300
250
200
150
100
@ 8.33V
mV Out = 33.6 ± 0.8(A)
50
0
0
2
4
6
Current (A)
8
10
The current in this trace was swept from zero to nine Amps, similarly to the 90-mil analysis. The
sensor output to current correlation from this graph is 4.0 ± 0.1 mV/V/A. The differences between the
90 and 60-mil traces is due to the field distribution/density differences between the two due to the
difference in width.
Resolution
The resolution of the sensor is a function of environmental electromagnetic noise, intrinsic noise, and
hysteresis. In most applications, the environmental noise is the limiting factor in resolution. Data and
information in this section are based upon non-filtered, non-amplified, non-shielded output. In this
“raw” configuration, a resolution of better than 1 mA was found. With proper filtering, amplifying and
shielding, the noise level can be decreased and thus the usable resolution will increase.
Hysteresis and Repeatability in GMR Current Sensors
All magnetic materials have an effect called magnetic hysteresis. This hysteresis contributes greatly to
the error values given above. Hysteresis also creates a potential that the same current can produce two
different voltage outputs. The hysteresis, and thus the error, is largest when the current changes
direction. If the current changes direction, the precision of the output at low currents decreases
significantly. The specified error of 0.7% will not be obtained again until the current goes above
approximately 2A. This guideline is very rough as applications vary.
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Application Notes
Another magnetic contribution to the error can be overcome by an initialization current. Often,
depending on the magnetic history (hysteresis) of the sensor, the initial outputs are different from
subsequent outputs as seen in the figure below:
Initialization of AA003-02
300
250
Output (mV)
200
Initial sweep
Series2
150
Series3
100
Series4
Series5
50
Series6
0
0
2
4
6
Current (A)
8
10
The initial sweep data has deviated from the other series of current sweeps. After the first sweep was
completed, the subsequent five sweeps fell right on each other. This shows that a lower error can be
obtained by “initializing” the sensor. After initialization, the error will be much lower until the
working current range is exceeded in either direction. Saturation of the device (currents in the 20A
range) as well as changing the applied current direction will increase the hysteresis/error.
For currents of approximately 2 Amps and smaller, the output repeatability is nominally 2% while
higher currents produce output repeatability errors of less than 1%. Low current measurements of an
initial current sweep may exceed 15% error in repeatability.
DATA ANALYSIS- Low Current Sensing
The low current analysis is handled here separately from the higher current analysis due to special
considerations that must be made, although much of the same hysteresis and resolution considerations
from high field sensing apply here. For low current sensing, two configurations of 0.010" wide traces
were used. The first analysis will be with an AA003-02 sensor over a single 10-mil trace and the
second analysis will consist of an AA003-02 sensor over seven 10-mil traces. With these traces,
milliamp and sub-milliamp currents are of interest. Due to the hysteresis at low currents as discussed
above, a biasing magnet was used to set the parts to approximately half of their linear range, or
approximately 20 mV/V. This bias point can be seen as the Y intercept in the figures below. In this
way, the output will not be near the natural zero current range, and thus, repeatability is increased.
With this configuration an alternating sense current will produce a bipolar output with a DC offset in
an AC application.
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Application Notes
Note that although a permanent magnet was used for biasing in these experiments, a better method is to
use a constant current. The current can be run on a trace parallel to the trace to be sensed, and will add
to the current of interest. The magnetic field from the bias current can be more closely controlled than
the field from a permanent magnet, which varies substantially with distance from the sensor. In
addition, provided the bias current is stable over temperature, the bias field at the sensor element will
also be stable over temperature. Permanent magnets often have large temperature coefficients, leading
to biasing changes with temperature.
AA003-02 over single 0.010" wide
0.0023" thick trace
155
mV Out = -29.19 ± 0.08(A)
154.5
@8.06V
Output (mV)
154
153.5
153
152.5
152
151.5
0
0.02
0.04
0.06
0.08
0.1
Current (A)
The sensor that was used to take this data was supplied with 8.06V. The marks on the graph are output
error bars that cover the expected error from this part due to the part’s intrinsic hysteresis and
measurement errors. The current was swept from zero to 100 mA and back to zero multiple times. In
this biased state, the sensor is extremely linear and hysteresis is low. A weighed linear fit shows a
-29.19 ± 0.08 mV/A correlation with 8.06V supplied which results in a sensitivity of 3.70 ± 0.01
mV/V/A.
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Application Notes
The same analysis was performed on the seven 0.010" wide traces of the same thickness. A voltage of
8.06V was again applied and the resulting graph is shown below in the figure below.
Output (mV)
AA003-02 over seven 0.010" wide
0.0023" thick traces
194
192
190
188
186
184
182
180
178
176
174
mV Out = 177.74 ± 0.06(A)
@8.06V
0
0.02
0.04
0.06
0.08
0.1
0.12
Current (A)
Seven traces were run under the part so that the magnetic fields from the seven traces are additive at
the sensor thus getting a much higher output with less applied current. To a first-order approximation,
theory predicts that the field will be increased seven fold from just a single trace. The sensitivity from
the single trace above is 3.7 mV/V/A; seven times this is 25.9 mV/V/A, which is not quite achieved.
This discrepancy is due to the different current distributions. The loss would not be as extreme if seven
times the current went through the single trace.
Resolution
Resolution is a function of environmental noise. By shielding, amplifying, and filtering, the low limit
and usable resolution can be greatly increased. The data for the analysis done here was with a “raw”
setup, no amplification or filtering. In a zero gauss chamber, single microamps were detected but the
measurement equipment limited any in-depth analysis.
Effects of Biasing
For the analysis done above, a small ceramic magnet was used to supply a magnetic bias field in a
direction which is parallel to the sensitive axis of the sensor. This magnetic bias “pushes” the output to
a certain value, which is now a “psuedo zero” field point. The magnetic field from a current carrying
conductor is also directional. If a current flows in such a direction as to add to the biasing field, the
output from the sensor will increase. Likewise, if a current flows in the opposite direction, its resultant
field will subtract from the biasing field, and the output will decrease. This directionality can be seen
by looking at the output slopes of the previous two graphs. In the first graph, the output displayed
shows the current produced a field opposite to the biasing magnetic field. Thus showing as the current
increases, the output of the sensor decreases. In the same respect, the second graph shows that the field
from the current was in the same direction as the biasing field.
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Application Notes
Offset Characteristics
When using the specified sensitivity to predict the output of a sensor, remember that the sensor
typically has a DC offset voltage. This is due to electrical bridge imbalance as well as external
magnetic field bias (earth’s field, magnets…). The output of the sensor without applying the current of
interest is the base line output. The effects of the current will be added to this base line value. For the
graphs shown on pages 130 and 131, the Y axis intercept is the base line offset. To determine the
output of the sensor for a given field, this Y intercept number must be added to the value obtained by
multiplying the current value by the slope.
AC
As mentioned previously, most information thus far has focused on DC applications. AC current
detection with an AA003-02 is unique and thus deserves special attention in a separate application.
Because the sensor is magnetically omni-polar, the output will be the same sign for either direction of
magnetic field. As an AC current changes direction, the field surrounding the conductor will also
change direction. The sensor’s output will produce a fully rectified output. Low current AC is
particularly laden with hysteretic errors. One method of creating both a bipolar output and a lower
error is to magnetically bias the sensor. Biasing is discussed above in this Engineering and Application
Notes booklet.
Part-to-Part Sensitivity
The data and evaluation thus far have focused on individual part performance. The part-to-part
performance will also be briefly examined here. Each current sensor is tested and sorted to be within
certain limits as given in the specification sections of this catalog. The main specification that affects
the output of the sensor is the sensitivity. The AA003-02 sensors are tested to a sensitivity range of 2.0
to 3.2 mV/V/Oe. The offset specification also affects the output. The offset is the zero current or
electrical imbalance of the Wheatstone bridge inside the sensor.
The magnetic field of the earth at NVE, is approximately 0.5G at a 70-degree angle to the horizon
(values will vary depending on geographical location). The effects of this magnetic field should be
analyzed in each application.
Care should be taken by the user to reduce the number and proximity of ferrous materials and magnetic
field producers around the sensor. This typically is not a concern, but in some highly populated boards,
this may be a necessity. Close proximity to such devices can increase the magnetic hysteresis or affect
the output. In turn, these devices will decrease the sensor’s output precision.
The output of the AA003-02 is functionally dependent on the distance between the sensor and the
current. The field from a current carrying conductor is inversely proportional to the distance from the
conductor. As the distance from the sensor to the conductor increases, the output from the sensor
decreases. Likewise, as the sensor moves closer to the conductor, the output will increase. For the data
analysis done in this report, the sensor was placed “live bug” over the current traces. In this
configuration, the actual sensor element is about 0.04" from the top of the PCB trace. The output will
increase with the current carrying conductor placed directly over-top of the sensor package. In this
configuration, the sensing element is approximately 0.02" from the surface of the conductor. This
distance change will account for an estimated doubling of sensor output.
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Application Notes
Current Sensing - Detailed Considerations
Care must be taken in interpreting the output waveform when using GMR as current sensors. GMR
sensors function as omnipolar sensors by producing positive output regardless of the magnetic field
direction. In the case of AC excitation, the bipolar field created by a sinusoidal AC current will
produce an output that will look like a full-wave rectified sinusoidal waveform. Biasing the sensor
partway up the curve will restore a sinusoidal output with a DC component.
Although most of the examples given in this section use the AA003-02 sensor element, any of NVE’s
AA-Series, AAH-Series, or AAL-Series analog sensors will function as a current sensor as described
above. The customer can select from a wide range of magnetic sensitivities in order to have the best
sensing characteristics for the current range to be detected.
Current Sensing Application Examples
• Non-intrusive AC or DC current detection or sensing
• PCB mounted current detection or sensing (PCB trace or strap current carrier)
• Toroidal Hall effect current detector or sensor replacements
• Industrial instrumentation
• Industrial process control
• Current probes
NVE has a current sensor evaluation kit, AG003-01, which has a variety of different size traces
complete with on-board sensors, available directly or through our distributors.
- 125 www.nve.com phone: 952-829-9217 fax: 952-829-9189
Application Notes
Magnetic Media Detection
General discussion
GMR Magnetic Field Sensors can be used for detecting different types of magnetic media. In this
situation, NVE defines magnetic media as material that has a distinct magnetic signature. The media is
typically a non-magnetic substrate with magnetic material placed in or on the substrate. Typically,
GMR sensors are used to “read” the magnetic signature by sweeping the substrate and the sensor past
each other.
Depending upon the application, the magnetic parts of the substrate can be detected indirectly by
sensing a perturbation of an externally applied field or sensed directly due to the part’s own field. The
output of the sensor will be a function of: (1) the magnetic properties of the media; (2) the working
gap; and (3) the type of sensor used.
Application examples
•
•
•
•
•
Magnetic ink detection
Magnetic stripe reading
Fine magnetic particle detection
Media magnetic signature detection
Magnetic anomaly detection in substrates
Basic concepts
For applications in which minimum size is not critical, external flux concentrators can be used to
increase sensor sensitivity. These external flux concentrators function in the same manner as the flux
concentrators within the sensor.
External flux concentrator
L gap
L concentrator
NVE
AAxxx-xx
External flux concentrator
Axis of Sensitivity
Flux concentration factor:
FC ~ L concentrator/L gap
Elongated pieces of soft magnetic material gather external magnetic flux and expose the sensor to a
magnetic field that is larger than the external magnetic field. For best results, two pieces of soft
magnetic material of the same size are used. The concentration factor is approximately the ratio of one
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Application Notes
flux concentrator’s length to the gap between the two flux concentrators. The long dimension of the
flux concentrators should be aligned with the sensitive axis of the NVE sensor. To minimize the gap,
the flux concentrators should butt up against the NVE sensor package.
Since the effective permeability of the flux concentrators is equal to the concentration factor, material
with permeability 100 or more times the concentration factor, will be more than sufficient. Hot rolled
iron wire or even cut off iron nails will work. Flux concentrators can be round or rectangular in cross
section for mounting considerations. The NVE sensor must be centered within the flux concentrators’
cross sectional area. The diameter of the flux concentrators should be an appreciable fraction of the
gap length or flux spreading in the gap will reduce the concentration factor. The flux concentration
achieved will depend on all dimensions. However, it will depend primarily on the ratio of the
concentrator length to gap. The best calculation, however, is an experimental measurement made with
an actual sensor and flux concentrators. For prototyping and production, the external flux concentrator
can be placed down on the PCB or other substrate. The top of the metal strip must be at least as high as
the sensor package to be truly effective.
It should be noted that a flux concentrator that increases the sensitivity of a GMR sensor by a factor of
five will also reduce the maximum field to which the sensor can respond to one-fifth its original value.
Currency Detection and Validation
Currency detection and validation is a very important application of magnetic media detection. NVE’s
sensors have been used for detecting the magnetic material in paper bills. This magnetic material can
be modeled as very small bar magnets. The magnetic field emitted by the bar magnets has two
detectable orientations. The first is the vertical (radial) component of the field, and second is the
horizontal (axial) component of the field. The sensitive axis of the sensor should be parallel with the
component of field desired, i.e., the horizontal axis, to pickup the horizontal component of the field.
Horizontal
Component
Vertical
Component
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Application Notes
The magnetic particles in the ink of most currencies, and also any magnetic stripes on the currency,
can be magnetized and demagnetized by an external field. With only the earth’s field present, the bill’s
magnetic properties can be seen. However, the signal increases when using an external field.
This external magnetic field can be set up in a few different orientations, either in a front/back biasing
configuration or positioned “upstream” of the sensor. The back biasing configuration typically consists
of an electro/permanent magnet glued to the under side of the sensor or to the under side of the PCB.
The magnet should be aligned to produce the minimum output from the sensor. The ferromagnetic
particles in the bill will magnetize and thus distort the field to produce a field in the sensitive direction
at the sensor. Front biasing works in much the same manner except in this case the source of external
field is coming from the other side of the bill.
Flux
Bill
AA002-02
Passive
mounting
4 leads, V+,VOut+, Out-
Magnet
Front biasing
Magnet
Back biasing
Positioning the magnet “upstream” from the sensor consists of magnetizing the bill before it reaches
the sensor—this terminology comes from an application where the bills are moving past the sensor on
a conveyer belt or rollers. With a magnet placed near the moving bill, the bill is magnetized before
passing the sensor. The application’s geometrical requirements, strength of magnet, as well as sensorbill distance will determine which configuration works the best in each application. The following are
some graphs that show the characteristics of back-biasing an AA002 sensor.
To determine the sensitivity of back biasing positioning, the magnet was moved along the sensors
sensitive axis. The goal was to position the magnet so that there is minimum field in the sensitive
direction. To obtain this, one pole of the magnet must be directly under the sensing resistors of the
bridge. Note the steep slope around the zero output, which makes exact positioning difficult.
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Application Notes
Characteristc of magnet moving in
sensitive direction
Offset voltage (V)
4.5
3.5
2.5
1.5
0.5
-0.5 0
0.2
0.4
0.6
0.8
-1.5
Relative postion (in)
The graph below shows the variation in signal at the sensor as the currency is moved farther away from
the GMR sensor element. Close proximity to the sensor is important in order to maximize output signal
from the sensor.
Characteristic of moving sensor further
from bill
8
V (mv) trial 1
Voltage out from amp (10x)
(mV)
7
V (mv) trial 2
6
V avg
5
4
3
2
1
0
-0.02
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Distance from bill to sensor package (in)
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Application Notes
In most currency detection applications, the signal from the bill is so small that it requires AC coupling
the sensor to a high gain low noise amplifier in order to get usable signal levels.
In order to achieve the highest possible signal, NVE’s most sensitive sensors are necessary. NVE’s
AA002-02, AAH002-02, and AAL002-02 sensors are recommended. These parts utilize large flux
concentrators for high sensitivity. These flux concentrators also contribute to the magnetic hysteresis
of the sensor. The hysteresis shows up mainly in a changing DC offset of the part. By AC coupling the
output of the sensor, the changes in magnetic field are seen at the output rather than the DC offset.
Another feature of AC coupling is a consistent output independent of the sensor’s orientation with
respect to the earth’s field. The device is sensitive enough to pick up the earth’s DC field. By AC
coupling, the DC offset contributed by the earth’s field, is not seen at the output.
Bipolar output signals are often very useful in currency detection and other magnetic media detection
applications. As a result, NVE recommends biasing the sensors in these applications by using a current
strap under the sensor to carry a bias current, and therefore bias the sensor higher, on its magnetic
operating characteristic.
Magnetic media detection and validation is an important and fast-growing application for magnetic
sensors. NVE’s sensors provide a reliable, non-contact, static or dynamic detection of the magnetic ink
on paper currency. NVE’s AA002 sensor can resolve the distinct features printed on U.S. and other
currency. NVE’s magnetic field sensors have been used for counterfeit detection, sorting, and simple
bill presence detection.
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Appendix
Appendix
Package Drawings and Specifications
Package Drawing – SOIC8
.193 (4.90)
.154 (3.91)
.236 (5.99)
NVE
XXXXX
-XX
.015 (.381)
x 45°
.154 (3.91)
.016 (.40) NOM.
.020 (.508)
.188 (4.77)
.017 TYP.
Dimensions: inch (mm)
.054 (1.37)
.061 (1.55)
.050 (1.27) x 6
BASIC
.004 (.10) MIN.
.010 (.26) MAX.
Note: SOIC8 Package has thermal power dissipation of 240°C/Watt in free air.
Attaching the package to a circuit board improves thermal performance.
Package Drawing – MSOP8
.118
(3.00)
.118 (3.00)
.193 (4.90)
NVE
XXX
.005 (.13) NOM.
.118 (3.00)
.021 (.533)
.154 (3.91)
.012 TYP.
.034 (.86)
.040 (1.02)
Dimensions: inches (mm)
.0256 (.65) x 6
BASIC
.004 (.10) MIN.
.012 (.31) MAX.
Note: MSOP8 Package has thermal power dissipation of 320°C/Watt in free air.
Attaching the package to a circuit board improves thermal performance.
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Appendix
Package Drawing – TDFN6 2.5 mm x 2.5 mm
2.00 ± 0.05
0.80 MAX
4
4
6
1.30 ± 0.05
2.50 ± 0.10
6
C0.10
PIN 1 ID
1
3
1
0.65 TYP. (4x)
3
0.30 ± 0.05(6x)
0.30 ± 0.05(6x)
2.50 ± 0.10
0.0-0.05
PIN 1 INDEX AREA
1.30 REF (2X)
0.20 REF.
Note: Dimensions in mm. TDFN6 package has thermal power dissipation of 320°C/Watt in free air.
Attaching the package to a circuit board improves thermal performance.
Package Drawing – TDFN SO8
PIN 1 INDEX AREA
0.75±0.05
4
4
1
1
6.00 ± 0.20
3.40 ± 0.15
Pin 1 ID
3.90 ± 0.15
5
0.65 ± 0.10 (8x)
8
5
5
4.900 ± 0.20
0.0-0.05 0.40 ± 0.05 (8x)
1.27 Typ. (6x)
3.81REF (2x)
0.75±0.05 MAX
Note: Dimensions in mm. TDFN SO8 Package has thermal power dissipation of 240°C/Watt in free air.
Attaching the package to a circuit board improves thermal performance.
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Appendix
Package Drawing – PLLP6 3.0 mm x 3.0 mm
3.10 (0.122)
3.00 (0.118)
3.10 (0.122)
3.00 (0.118)
0.98 (0.038)
0.93 (0.036)
0.45 (0.018)
0.35 (0.014)
1.55 (0.061)
1.45 (0.057)
0.45 (0.018)
0.40 (0.016)
0.12 (0.005)
0.02 (0.001)
2.30 (0.091)
2.20 (0.087)
1.00 (0.039)
0.85 (0.033)
0.05 (0.002)
0.00 (0.000)
Note: The PLLP6 package has thermal power dissipation of 320°C/Watt in free air. Attaching the package to
a circuit board improves thermal performance. Dimensions are in mm (inches).
Note on Lead-Free Packages
The electronics industry has been working to provide lead-free products in response to concerns about
the environmental impact of the use of lead (Pb) in solder finishes. Increasing customer demand and
directives to decrease the amounts of lead in consumer electronics products from governments around
the globe, drives this effort.
Lead-free finishes utilizing pure tin (Sn) have already been qualified at NVE and are available in most
of our products. However, additional lead times are associated with these parts.
Since most lead-free solders being used in board assembly environments have higher melting
temperatures than traditional tin-lead solders, higher reflow temperatures may be necessary to form an
equivalent solder joint between the component and the PC board. NVE characterizes all lead-free
packages using elevated temperature (245°C to 260°C) reflow profiles characteristic of lead-free board
assembly environments. All lead-free products will be identified with an “E” suffix on the part number
and a lower case “e” marking on the package.
This lead-free transition is an important component of NVE’s commitment to take an active part in
protecting the environment and our responsibility to our customers and the communities around the
world in which we do business. We remain dedicated to meeting our customers’ requirements and
expectations.
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Appendix
Recommended Solder Reflow Profile
NVE recommends the following soldering profile:
300
For leaded (Pb) parts, the peak temperature shown in this profile can be decreased to as low as 230°C.
Exceeding 265°C at peak or the time at peak temperature shown in this profile can damage the parts.
Specifically:
1.
AA- and AD-Series sensors are rated at 150°C maximum storage temperature. They can withstand
the solder profile shown above with no harmful effects. However, temperatures above 265°C for
even a brief period or extended periods above 160°C can cause degradation of the GMR sensor
element.
2.
AKL- and DD-Series parts contain an on-chip EEPROM. Exposure to temperatures in excess of
265°C can cause EEPROM data corruption, which will cause the parts to fall out of specification.
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Appendix
Magnet Data
NVE supplies Ceramic 8 magnets in some of our GMR sensor evaluation kits. The characteristics for
these magnets are given below:
Material Type
Ceramic 8 (C8)
Maximum Operating Temperature
300°C
Curie Temperature
450°C
Temperature Coefficient of Flux Density
-0.20 %/°C
Maximum Energy Product
3.5 MGOe
Residual Induction
3850 Gauss
Coercive Force
2950 Oersteds
Ceramic 8 M agnetic Characteristics
4500
3500
3000
2500
2000
1500
Flux D e nsity, G auss (G )
4000
-35C
+25C
+85C
1000
500
0
-5000
-4000
-3000
-2000
-1000
0
De magne tizing Force , O e rste ds (O e )
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Appendix
Magnet drawings for the two round disc magnets included in the GT Sensor evaluation kits are given
below. These magnets are available from NVE as production parts. Contact NVE for pricing and
delivery information. In addition, NVE can have custom magnets built for specific applications in
Ceramic 8 or Alnico 8 materials. Please contact NVE for more details.
Ceramic 8 Disc Magnets
Note: All Dimensions in mm.
N
N
S
S
Magnet Part Number
Diameter (mm)
Length (mm)
12216
6
4
12217
3.5
4
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Appendix
Part Numbers and Marking Codes
NVE’s part number format consists of two or three letters, then three numbers, a dash, and then two
more numbers, and in some cases a final letter. Here is an example:
AAH004-00E
The meanings of the numbers and letters are defined as follows:
First Two
Letters
AA
AB
General Part Description
Analog output magnetometer or spin valve sensor
Analog output gradiometer
AD
Digital output magnetometer
AG
Evaluation kit or printed circuit board assembly
AK
Digital output gradiometer
BD
Custom digital output magnetometer
DB
Digital input signal processing IC
DC
Voltage regulator
DD
Analog input signal processing IC
Third Letter
GMR Material Used In Product
No third letter indicates NVE’s standard multilayer material
H
High sensitivity, high temperature multilayer material
L
Low hysteresis, high temperature multilayer material
V
Spin valve material with synthetic anti-ferromagnet pinning
Three Digits
xxx
Two Digits
After Dash
Consecutive Part Number
Meaning for AD-Series parts is described in the GMR Switch section of this
catalog; other products have numbers assigned consecutively with no meaning
implied
Package Type
-00
MSOP 8 pin package
-01
Raw IC (die); available in diced wafer on blue tape or waffle pack form
-02
SOIC 8 pin package
-07
Non-semiconductor style package; used for eval kits and PCBs
-10
TDFN6 2.5mm X 2.5mm 6 pin package
-11
PLLP6 3.0mm X 3.0mm 6 pin package
-12
TDFN SO8 4.9mm X 6.0mm 8 pin package
Final Letter
E
Consecutive Part Number
No final letter means a standard package; E means a lead-free package
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Appendix
Some of NVE’s products are delivered in packages that are too small to be marked with the complete
part number. In these cases a three-letter code is used to identify the part. The following table provides
a cross-reference from part number to marking code:
NVE Part Number
AA004-00
AA006-00
AAH004-00
AAV001-11
AAV002-11
AB001-00
ABH001-00
ABL004-00
ABL005-00
ABL006-00
ABL014-00
ABL015-00
ABL016-00
ABL004-10
ABL005-10
ABL006-10
ABL014-10
ABL015-10
ABL016-10
AD004-00
AD005-00
AD006-00
AD020-00
AD021-00
AD022-00
AD023-00
AD024-00
AD024-10
AD104-00
AD105-00
AD106-00
AD120-00
AD121-00
AD122-00
AD123-00
AD124-00
AD204-00
AD205-00
AD206-00
AD220-00
AD221-00
AD222-00
AD223-00
AD224-00
AD304-00
AD305-00
AD306-00
AD320-00
AD321-00
AD322-00
Code
CBD
CBC
CBF
BBP
BBQ
CBG
CBH
FDB
FDC
FDL
FDD
FDF
FDM
FDG
FDH
FDN
FDJ
FDK
FDP
BBH
BBG
BBJ
BBK
BBB
BBC
BBD
BBF
BBL
DBH
DBG
DBJ
DBK
DBB
DBC
DBD
DBF
FBH
FBG
FBJ
FBK
FBB
FBC
FBD
FBF
GBH
GBG
GBJ
GBK
GBB
GBC
NVE Part Number
AD323-00
AD324-00
AD404-00
AD405-00
AD406-00
AD420-00
AD421-00
AD422-00
AD423-00
AD424-00
AD504-00
AD505-00
AD506-00
AD520-00
AD521-00
AD522-00
AD523-00
AD524-00
AD604-00
AD605-00
AD606-00
AD620-00
AD621-00
AD622-00
AD623-00
AD624-00
AD704-00
AD705-00
AD706-00
AD720-00
AD721-00
AD722-00
AD723-00
AD724-00
AD081-00
AD082-00
AD083-00
AD084-00
AD821-00
AD822-00
AD823-00
AD824-00
AD921-00
AD922-00
AD923-00
AD924-00
ADH025-00
BD012-00
DB001-00
DC001-10
DC002-10
Code
GBD
GBF
HBH
HBG
HBJ
HBK
HBB
HBC
HBD
HBF
JBH
JBG
JBJ
JBK
JBB
JBC
JBD
JBF
KBH
KBG
KBJ
KBK
KBB
KBC
KBD
KBF
LBH
LBG
LBJ
LBK
LBB
LBC
LBD
LBF
BDB
BDC
BDD
BDF
MBB
MBC
MBD
MBF
NBB
NBC
NBD
NBF
MBL
ZBF
FFD
FFB
FFC
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Appendix
The following table provides a cross-reference from marking code to part number:
Code
BBB
BBC
BBD
BBF
BBG
BBH
BBJ
BBK
BBL
BBP
BBQ
BDB
BDC
BDD
BDF
CBC
CBD
CBF
CBG
CBH
DBB
DBC
DBD
DBF
DBG
DBH
DBJ
DBK
FBB
FBC
FBD
FBF
FBG
FBH
FBJ
FBK
FDB
FDC
FDD
FDF
FDG
FDH
FDJ
FDK
FDL
FDM
FDN
FDP
FFB
FFC
NVE Part Number
AD021-00
AD022-00
AD023-00
AD024-00
AD005-00
AD004-00
AD006-00
AD020-00
AD024-10
AAV001-11
AAV002-11
AD081-00
AD082-00
AD083-00
AD084-00
AA006-00
AA004-00
AAH004-00
AB001-00
ABH001-00
AD121-00
AD122-00
AD123-00
AD124-00
AD105-00
AD104-00
AD106-00
AD120-00
AD221-00
AD222-00
AD223-00
AD224-00
AD205-00
AD204-00
AD206-00
AD220-00
ABL004-00
ABL005-00
ABL014-00
ABL015-00
ABL004-10
ABL005-10
ABL014-10
ABL015-10
ABL006-00
ABL016-00
ABL006-10
ABL016-10
DC001-10
DC002-10
Code
FFD
GBB
GBC
GBD
GBF
GBG
GBH
GBJ
GBK
HBB
HBC
HBD
HBF
HBG
HBH
HBJ
HBK
JBB
JBC
JBD
JBF
JBG
JBH
JBJ
JBK
KBB
KBC
KBD
KBF
KBG
KBH
KBJ
KBK
LBB
LBC
LBD
LBF
LBG
LBH
LBJ
LBK
MBB
MBC
MBD
MBF
MBL
NBB
NBC
NBD
NBF
ZBF
NVE Part Number
DB001-00
AD321-00
AD322-00
AD323-00
AD324-00
AD305-00
AD304-00
AD306-00
AD320-00
AD421-00
AD422-00
AD423-00
AD424-00
AD405-00
AD404-00
AD406-00
AD420-00
AD521-00
AD522-00
AD523-00
AD524-00
AD505-00
AD504-00
AD506-00
AD520-00
AD621-00
AD622-00
AD623-00
AD624-00
AD605-00
AD604-00
AD606-00
AD620-00
AD721-00
AD722-00
AD723-00
AD724-00
AD705-00
AD704-00
AD706-00
AD720-00
AD821-00
AD822-00
AD823-00
AD824-00
ADH025-00
AD921-00
AD922-00
AD923-00
AD924-00
BD012-00
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Appendix
Definitions and Conversion Factors
Definitions:
CSK or Sink: Current sinking output, also referred to as Open Collector output.
Differential: The field difference between the Operate Point and the Release Point.
Electrical Offset: The inherent imbalance of the bridge expressed in differential voltage output.
HBM: Human Body Model for ESD specifications.
Hysteresis: The maximum deviation in volts between the output with increasing field and the output
with decreasing field, where the applied field is unipolar (applied in either a positive or negative
direction, without crossing the zero field point), divided by Voltage Span. Expressed as a percentage.
Input Voltage Range: The voltage range that can be applied across the bridge.
IOL (Current Output Low): The output current in the low (logic 0) state (output stage switched on).
Max Output: A specification given in millivolts per applied voltage. This is the maximum output
voltage possible. This output condition is achieved when one set of resistors is in magnetic saturation
(have achieved the maximum resistance change possible) while the other pair are at zero applied
magnetic field.
Nonlinearity: The maximum deviation from a linear fit taken over the Field Range divided by the
Voltage Span. Expressed as a percentage.
Off-axis Characteristic: A specification that describes the variation in sensor output versus the angle
between the applied field direction and the sensitive axis of the GMR sensor with constant electrical
and magnetic inputs applied. Applicable to non-integrated bridge sensors. The output will vary as the
cosine of the angle rotated.
Operate Point: The field level which produces a logical change in state from “0” to “1” in NVE’s
digital magnetic field sensors ADXXX-XX.
Operating Frequency: Frequency range within which a sensor will produce a responsive output.
Output Leakage Current (Current Output High): The output current in the high (logic 1) state
(output stage switched off).
Output Saturation Voltage (Voltage Output Low): The output voltage in the low (logic 0) state
(output stage switched on).
RBP: Reverse Battery Protection.
Release Point: The field level which produces a logical change in state from “1” to “0” in NVE’s
digital magnetic field sensors ADXXX-XX.
Resistor Separation: This is the mean separation between the two pairs of resistors, in a Gradiometer
or Differential sensor.
Sensitivity: A measure of the output magnitude based on electrical and magnetic input conditions.
Expressed in millivolts of differential output per applied voltage per Oersted.
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Appendix
Specified Linear Range: Typically 70% of the field it takes to saturate the part. Field dependent
specifications are based upon this range.
TCOI (Temperature Coefficient of Output at Constant Input Current): The variation of the
output voltage over temperature with a constant input current applied. Expressed as a percentage per
unit temperature change.
TCOV (Temperature Coefficient of Output at Constant Input Voltage): The variation of the
output voltage over temperature with a constant input voltage applied. Expressed as a percentage per
unit temperature change.
TCR (Temperature Coefficient of Resistance): The variation of the GMR resistors over
temperature. Expressed as a percentage per unit temperature change.
Voltage Span: The differential output voltage taken from zero to 70% of the saturation field level.
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Appendix
Conversion Factors
To Convert
µWb
A/cm
A/m
At
G
G
G
G
G
G
G
Gb
kA/m
maxwell
maxwell
mT
maxwell
nT
nT
Into
maxwell
Oe
Oe
Gb
Oe
T
mT
nT
Wb/cm2
Wb/in2
Wb/m2
At
Oe
Wb
µWb
G
volt second
G
gamma (γ)
Multiply by
102
1.256
1.256 x 10-2
1.256
1 (when µo=1)
10-4
10-1
105
10-8
6.452 x 10-8
10-4
0.796
1.256 x 101
10-8
10-2
10
10-8
10-5
1
Oe
A/cm
7.962 x 10-1
Oe
Oe
T
T
volt second
volt second
Wb
Wb/cm2
Wb/m2
A/m
kA/m
G
Wb/m2
maxwell
Wb
maxwell
G
G
7.962 x 101
7.962 x 10-2
104
1
108
1
108
108
104
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About NVE
About NVE
NVE Corporation develops and sells devices using spintronics, a nanotechnology we helped pioneer,
which utilizes electron spin rather than electron charge to acquire, store and transmit information.
We make spintronics practical by manufacturing high-performance products including sensors and
couplers that are used in industrial, scientific, and medical applications. We have also licensed our
spintronic magnetoresistive random access memory technology, commonly known as MRAM.
Sensors acquire information, couplers transmit information, and memories store information. Thus our
technology can provide the eyes, nerves, and brains of electronic systems. NVE’s award-winning
products are sold through a worldwide distribution network.
The company is located in Eden Prairie, Minnesota, a suburb of Minneapolis.
Please visit our web site or call our toll free number for information on products, sales, or distribution.
An ISO 9001 Certified Company
NVE Corporation
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Eden Prairie, MN 55344 USA
Telephone: (952) 829-9217
Fax: (952) 829-9189
www.nve.com
e-mail: [email protected]
©NVE Corporation
All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent
of the copyright owner.
SB-00-014
February 6, 2012
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Terms and Conditions
Datasheet Limitations
The information and data provided in datasheets shall define the specification of the product as agreed
between NVE and its customer, unless NVE and customer have explicitly agreed otherwise in writing.
All specifications are based on NVE test protocols. In no event however, shall an agreement be valid in
which the NVE product is deemed to offer functions and qualities beyond those described in the
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Information in this catalog is believed to be accurate and reliable. However, NVE does not give any
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It is customer’s sole responsibility to determine whether the NVE product is suitable and fit for the
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Terms and Conditions
applications and the products or of the application or use by customer’s third party customers. NVE
accepts no liability in this respect.
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Stress above one or more limiting values (as defined in the Absolute Maximum Ratings System of IEC
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