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Texas Instruments Current Sense Amplifiers (Rev. D) Selection guides
Current Sense Amplifiers
ti.com/currentsense
2019
Current Sense Amplifiers
Introduction
What are Current Sense Amplifiers?
Current sense amplifiers, also called current shunt monitors, are specialized
differential amplifiers with a precisely matched resistive gain network with the
following characteristics:
• Designed to monitor the current flow by measuring the voltage drop across
a sense element, typically a shunt resistor
• Tend to be easier to use, more precise and less prone to noise
• Support currents from 10s of µA to 100s of A
• Natively support common-mode voltages from -16 to +80 V and with
additional circuitry up to 100s of volts
System benefits addressed by using current sense amplifiers:
• Real-time overcurrent protection
• Current and power monitoring for system optimization
• Current measurement for closed-loop feedback
Analog Output
+
_
Integrates the full analog signal
processing and provides a voltage
or current output.
Digital Output
Key Parameters
Common Mode Range:
This specification defines the DC voltage range at the input of an amplifier with
respect to ground. Current sense amplifiers are typically designed to support
common-mode voltages well beyond the chip supply voltage. For example, the
INA240 is capable of supporting a common-mode voltages between -4 V to +80 V
while running on a supply as low as 2.7 V.
Offset Voltage:
This is a differential DC error at the input of the amplifier. Historically, to reduce
the impact of amplifiers with high offsets, larger value shunt resistors were used
to increase the measured voltage drop. Today, TI is able to offer current sense
amplifiers with offsets as low as 10µV, enabling higher precision measurements
at low currents and allowing the use of smaller value shunt resistors for improved
system efficiency.
Gain:
Current sense amplifiers come with various gain options that have robust
performance over temperature and process variations by integrating a precisely
matched resistive gain network. The gain options for fixed gain amplifiers vary
from 0.125 V/V to 1000 V/V with gain errors as low as 0.01%.
Temperature Stability:
Current sense amplifiers integrate the amplifier along with all the gain-setting
resistors which enables small and unified temperature drift. This allows for robust
current measurements across the whole specified temperature range. The achieved
temperature stability is one of the key advantages current sense amplifiers have over
discrete implementations.
Integrates the full signal conditioning
path and utilizes a standard 2-wire
digital interface.
Comparator Output
_
_
+
+
Provides a simple ALERT signal when
the load current exceeds a threshold.
Integrated Shunt
+
_
Offers a low-drift, precision integrated
sense element.
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Current Sense Amplifiers Guide 2019
Texas Instruments
Current Sense Amplifiers
Key Design Considerations
High-Side Measurements
Current sensing techniques connect the current sense element
between the supply bus and the load.
System Advantages:
• Able to detect load short to ground
• Current is monitored directly from the source
• High immunity to ground disturbance
System Challenges:
• High bus voltage limits the availability of high input common-mode
voltage devices
+5V
Bus
Voltage
INA240
+5V
+
RS
–
ADS114
I2C
LOAD
Advantages Over Discrete Current Sense Circuit:
• Integrated gain resistors provide excellent matching to enable a
higher performing and more stable platform
• Reduction in board space requirements
• High dynamic changes in the common-mode voltage are difficult
to achieve with standard op amps
• Unique input architecture allows for the common-mode voltage
to greatly exceed the device supply voltage
Low-Side Measurements
Current sensing techniques connect the current sense element
between the load and ground.
System Advantages:
• Simple to implement and low-cost solution
• Wide range of available options
System Challenges:
• Difficult to detect load short to ground
• System ground disturbance by the shunt resistor
Advantages Over Discrete Current Sense Circuit:
• Integrated gain resistors provide excellent matching to enable a
higher performing and more stable platform
• Reduction in board space requirements
• True differential measurement across the shunt resistor
• Lower VOFFSET saves system power by enabling the use of
smaller value shunt resistors to achieve the same error level
Bus
Voltage
LOAD
INA181
+5V
RS
+
–
ADS114
I2C
Total Error
• For light loads with small current values that result in small
differential voltage signals at the input, the total error will be
dominated by the amplifier’s offset voltage. Low input offsets are
critical to achieving accurate measurements at the low end of the
dynamic range.
• For heavy loads with large current values that result in large
differential voltage signals at the input, the total error will be
dominated by the amplifier’s gain error.
Texas Instruments
Current Sense Amplifiers Guide 2019
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3
Current Sense Amplifiers
Reference Designs
Current sensing reference designs. See more designs online at ti.com/referencedesigns.
Design Number
Description
Bi-Directional eFuse
Automotive Precision eFuse
Current
Shunt
Reverse
Polarity
Protection &
Switch
Battery
/ LOAD
Battery
/ LOAD
+
INA300
INA300
+
TIDA-00795
One of the keys to preventing damage in automotive
electronic systems is the ability to detect and react
to potentially damaging conditions as rapidly as
possible. This INA300-Q1 eFuse reference design is
focused on providing high accuracy and fast response
over-current protection at current levels as high as
30 A and scalable to > 100 A.
Transient
Supressiion
Transient
Supressiion
Bus Supply
400 V
VSENSE
RSHUNT
+
- VSENSE +
R1 10 Ω
10K Ω
- VSENSE +
R1 10 Ω
Three-phase Current Measurements
for Motor
TIDA-00753
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Current Sense Amplifiers Guide 2019
Device Supply
VS (2.7 to 5.5 V)
VBus
RZ
Load
Maximizing motor control requires accurate current
measurement. This reference design featuring
the INA199 demonstrates a method for enhancing
the signal chain on the output of a current transformer.
In addition, this circuit offers significant power
savings by lowering the burden resistor value.
4.75K Ω
600 V
P-FET
OPA333
-
TIDA-00528
This reference design demonstrates a simple, nonisolated technique using a precision op amp and a
high voltage P-FET to extend the common-mode voltage
of a current sense amplifier up to 400 V. With minor
component changes, this design can be optimized
for any voltage ranging from 40 to 400 V.
I = VSENSE / R1
5.1 V Zener
36 V Transorb
300K Ω
40 V to 400 V Unidirectional Current/
Voltage/Power Monitoring
INA226
IN-
IN+
RSHUNT
C
SCL
SDA
SCL MicroController/
USBDIG
SDA
GND
INA199
+
C
OUT
–
C
INTDKCT
0–300 A
N=3000
VS
IN+
REF
0.1 E, 1W
15ppm,
2515
Texas Instruments
Current Sense Amplifiers
Reference Designs
Current sensing reference designs. See more designs online at ti.com/referencedesigns.
Design Number
Description
DC-DC
48 V to 5 V
5V
Option to provide 3.3 V
to Launchpad™
3.3 V
LDO 3.3 V
3.3 V
LM5018
LP38691
VREF 3.3 V
IC
IA
/PWM
enable
/PCB OT
alert
DC input
LMG5200
LMG5200
PCB
overtemperature
DC input
12 V to 60 V
GaN Driver
6
PWM_AH
PWM_AL
PWM_BH
PWM_BL
PWM_CH
PWM_CL
INA240
GaN Driver
4
INA240
GaN Driver
VA,VB,
VC, VDC
INA240
LaunchPad™ interface connector
TIDA-00913
This design realizes a 48 V/10A 3-phase GaN inverter with
precision in-line shunt-based phase current sensing for
accurate control of precision drives such as servo drives.
One of the largest challenges with in-line shunt-based
phase current sensing is the high common-mode voltage
transients during PWM switching. The INA240 current sense
amplifier overcomes this problem using enhanced PWM
rejection.
REF3333
IB
Buffer for PWM w/ OE
48 V 3-Phase Inverter with Shunt-based
In-line Motor Phase Current Sensing
LMG5200
Phase A
Phase B
Phase C
TMP302
Motor terminal
VA
VB
VC
AC Motor
EMI filter
(optional)
10-V to 20-V DC
TIDA-00440
This design provides a reference solution to
measure insulation resistance up to 100MΩ. It has
an on-board isolated 500 V DC power supply and an
isolated signal conditioning circuit to measure the
leakage current. This design is useful to find leakage
due to insulation breakdown in transformer and motor
windings.
R LIMIT
LDO
5V_VCC2
LDO
(Fly-BuckTM)
MUX
TS5A23157
INA225
To
MCU
V SENSE
150-V
to
800-V
DC
Flyback
(DC/DC)
UCC28711
500-V DC
R CAL
LM5160
V SENSE
Digital
Isolator
ISO
7640
R ISO
R ISO = Insulation resistance
R CAL = Calibration resistance
Texas Instruments
Low-voltage DC/DC
AMC1200
Leakage Current Measurement Reference
Design for Determining Insulation
Resistance
5V_VCC1
Basic isolation
Current Sense Amplifiers Guide 2019
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5
Analog Output Current Sense Amplifiers
Featured Products
AEC-Q100
Available
Bi–Directional
Low–Side
For more information see: ti.com/currentsense.
Description
INA190
Family
4
4
4
1.8 V, High-precision Current Sense Amplifier with Power Down
-0.1 to 40
10
0.1
0.1
10 UQFN,
6 WCSP,
6 SC70
INA210
Family
4
4
4
High performance, Zero-Drift Current Sense Amplifier
-0.3 to 26
35
0.1
0.02
10 UQFN,
6 SC70
4
4
4
High AC CMRR High Common Mode Current Sense Amplifier for
Motor & Solenoid Control
-4 to 80
25
0.05
0.05
Ultra-small, 5 V Current Sense Amplifier
1.8 to 5.5
100
0.06
0.01
4
Value line, Zero-Drift Current Sense Amplifier
-0.3 to 26
150
0.1
0.03
4
350kHz Bandwidth, Unidirectional Current Sense Amplifier for
Cost-sensitive Applications (Single, Dual, & Quad Options)
-0.2 to 26
150
0.2
0.1
8 TSSOP,
8 SOIC
10 UQFN,
4 WSCP
10 UQFN,
6 SC70
5 SOT-23,
8 VSSOP,
14 TSSOP
6 SOT-23,
10 VSSOP,
20 TSSOP
Part
Number
INA240
Family
INA216
Family
INA199
Family
4
4
Common Mode
Voltage Range
Input Offset
±µ V
Max
Input
Offset Drift
±µ V/°C
Typ
Gain Error
% Typ
Package(s)
INAx180
Family
4
INAx181
Family
4
4
4
350kHz Bandwidth, Bidirectional Current Sense Amplifier for
Cost-sensitive Applications (Single, Dual, & Quad Options)
-0.2 to 26
150
0.2
0.1
4
4
4
40 V Bidirectional, Precision Current Sense Amplifier
-0.1 to 40
50
0.05
0.02
6 SC70
110 V High Voltage, High Bandwidth, Unidirectional
Current Sense Amplifier
120 V High Voltage, High Bandwidth, High-side
Current Sense Amplifier
350kHz Bandwidth, High-Precision, Bidirectional Current Sense
Amplifier in SOT-563 Package
-4 to 110
100
0.2
0.02
5 SOT-23
2.7 to 120
100
0.2
0.02
5 SC70
-0.2 to 26
55
0.2
0.05
6 SOT-563
Programmable-Gain, Zero-Drift, High Accuracy
0 to 36
150
0.2
0.05
8 MSOP
High Common Mode, High-Speed
Current Sense Amplifier
4.5 to 76
265
6
0.6
8 VSSOP
High-Speed Current Sense Amplifier
-2 to 42
900
2.6
0.25
6 SOT-23
High Accuracy, Zero-Drift Current Sense Amplifier with 0.1%,
15 PPM/°C 2mΩ Integrated Shunt
High AC CMRR High Common Mode Current Sense Amplifier
Solenoid Control with 0.1%, 15 PPM/°C 2mΩ Integrated Shunt
Overcurrent Protection High-Speed, Precision Current Sense
Amplifier with Integrated Comparator
Overcurrent Protection High-Speed, Precision Current Sense
Amplifier with Integrated Dual Comparators
Overcurrent Protection High-Speed, Precision Current Sense
Amplifier with Integrated Window Comparator
Cost-efficient Current Sense Amplifier with
Integrated Standalone Comparator
0 to 36
50mA
25µA/°C
0.3
16 TSSOP
-4 to 80
12.5mA
25µA/°C
0.25
20 TSSOP
0 to 36
35
0.1
0.03
8 VSSOP
0 to 36
30
0.02
0.02
14 TSSOP
0 to 36
30
0.02
0.02
14 TSSOP
-0.2 to 26
150
0.1
0.1
8 UQFN
INA186
Family
INA293
Family
INA290
Family
INA185
Family
INA225
LMP8481
Family
LMP8640
Family
INA250
Family
INA253
Family
INA301
Family
INA302
Family
INA303
Family
INA381
Family
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Preview devices as of Q2 2019
Digital Output Power Monitors
Measurement
Parameter
Values
Description
4
4
I, V, P
Ultra-High Accuracy, Current, Voltage, & Power
INA260
4
4
I, V, P
INA233
4
4
I, V, P, E
Part
Number
INA226
AEC-Q100
Available
Low–Side
Bi–Directional
Featured Products
4
INA229
4
4
4
I, V, P, E
Ultra-High Accuracy, Current, Voltage, & Power Monitor with
0.1%, 15 PPM/°C 2mΩ Integrated Shunt
High Accuracy, Current, Voltage, Power, & Energy
Monitor with 1.8 V I2C/PMBus
85 V Current/Voltage/Power/Energy/Charge Monitoring Device
with SPI Interface with Internal Temperature Sensor
INA3221
4
4
4
I, V
Triple-channel, Current & Voltage Monitor with Alert
Common
Mode
Voltage
Range
Input
Offset
±µ V
Max
Input
Offset Drift
±µ V/°C
Typ
Gain
Error
% Typ
0 to 36
10
0.02
0.02
Package(s)
10 VSSOP
0 to 36
5mA
1µA/°C
0.02
16 TSSOP
0 to 36
10
0.02
0.02
10 VSSOP
0 to 85
10
0.01
0.02
10 VSSOP
16 VQFN
0 to 26
80
0.1
0.1
16 VQFN
Preview devices as of Q2 2019
Texas Instruments
Current Sense Amplifiers Guide 2019
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