Texas Instruments | LMP9007x/LMP90080 Sensor AFE System: Multi-Channel, Low-Power 16-Bit Sensor AFE With True Continuous Background Calibration (Rev. H) | Datasheet | Texas Instruments LMP9007x/LMP90080 Sensor AFE System: Multi-Channel, Low-Power 16-Bit Sensor AFE With True Continuous Background Calibration (Rev. H) Datasheet

Texas Instruments LMP9007x/LMP90080 Sensor AFE System: Multi-Channel, Low-Power 16-Bit Sensor AFE With True Continuous Background Calibration (Rev. H) Datasheet
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LMP90077, LMP90078, LMP90079, LMP90080
SNAS521H – JULY 2011 – REVISED JANUARY 2016
LMP9007x/LMP90080 Sensor AFE System: Multi-Channel, Low-Power 16-Bit Sensor AFE
With True Continuous Background Calibration
1 Features
•
•
1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
16-Bit Low-Power Sigma Delta ADC
True Continuous Background Calibration at All
Gains
In-Place System Calibration Using Expected
Value Programming
Low-Noise Programmable Gain (1x - 128x)
Continuous Background Open/Short and Out of
Range Sensor Diagnostics
8 Output Data Rates (ODR) with Single-Cycle
Settling
2 Matched Excitation Current Sources from 100
µA to 1000 µA (LMP90080/LMP90078)
4-DIFF / 7-SE Inputs (LMP90080/LMP90079)
2-DIFF / 4-SE Inputs (LMP90078/LMP90077)
7 General Purpose Input/Output Pins
Chopper-Stabilized Buffer for Low Offset
SPI 4/3-Wire with CRC Data Link Error Detection
50 Hz to 60 Hz Line Rejection at ODR ≤13.42
SPS
Independent Gain and ODR Selection per
Channel
Supported by WEBENCH® Sensor AFE Designer
Automatic Channel Sequencer
Key Specifications
– ENOB/NFR: Up to 16/16 Bits
– Offset Error (typ): 8.4 nV
– Gain Error (typ): 7 ppm
– Total Noise: <10 µV-rms
– Integral Non-Linearity (INL Max): ±1 LSB
– Output Data Rates (ODR): 1.6775–214.65
SPS
– Analog Voltage, VA: 2.85 to 5.5 V
– Operating Temp Range: –40°C to 125°C
– Package: 28 Pin Exposed Pad
2 Applications
•
•
•
Temperature and Pressure Transmitters
Strain Gauge Interface
Industrial Process Control
3 Description
The LLMP9007x and LMP90080 are highly
integrated, multi-channel, low-power 16-bit Sensor
AFEs. The devices feature a precision, 16-bit Sigma
Delta Analog-to-Digital Converter (ADC) with a lownoise programmable gain amplifier and a fully
differential high impedance analog input multiplexer.
A true continuous background calibration feature
allows calibration at all gains and output data rates
without interrupting the signal path. The background
calibration feature essentially eliminates gain and
offset errors across temperature and time, providing
measurement accuracy without sacrificing speed and
power consumption.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
HTSSOP (28)
9.70 mm × 4.40 mm
LMP90077
LMP90078
LMP90079
LMP90080
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Typical Sensor Application
2 -Wire RTD
3-Wire RTD
IB1
VIO
SCLK
IB2
CSB
1
+
VREFP1 VREFN1
VA
4-Wire RTD
Thermocouple
VA
2
3
4
VIN0
...
VIN2
...
VIN4
...
VIN6/VREFP2
VIN7/
VREFN2
GND
SDO/DRDYB
LMP90080
LM90xxx 16-bit Sensor AFE Family of Products
MicroController
SDI
D0
...
D6/DRDYB
CLK/XIN XOUT
LEDs/
Switches
Product
Channel Configuration
LMP90080
4 Differential/7 Single-Ended
Current Sources
Yes
LMP90079
4 Differential/7 Single-Ended
No
LMP90078
2 Differential/4 Single-Ended
Yes
LMP90077
2 Differential/4 Single-Ended
No
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LMP90077, LMP90078, LMP90079, LMP90080
SNAS521H – JULY 2011 – REVISED JANUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Description (continued).........................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
9
1
1
1
2
3
3
4
5
Absolute Maximum Ratings ...................................... 5
ESD Ratings.............................................................. 5
Recommended Operating Conditions....................... 6
Thermal Information .................................................. 6
Electrical Characteristics........................................... 6
Timing Requirements .............................................. 11
Timing Requirements - CSB Timing ....................... 11
Timing Requirements - SCLK and SDI Timing ....... 11
Timing Requirements - SDO Timing With DOD1.... 11
Timing Requirements - SDO Timing with DOD2 .. 11
Timing Requirements - SDO and DRDYB Timing 11
Typical Characteristics .......................................... 15
Detailed Description ............................................ 20
9.1
9.2
9.3
9.4
9.5
9.6
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
Register Maps .........................................................
20
20
21
29
32
43
10 Application and Implementation........................ 53
10.1 Application Information.......................................... 53
10.2 Typical Applications .............................................. 54
11 Power Supply Recommendations ..................... 60
12 Layout................................................................... 60
12.1 Layout Guidelines ................................................. 60
12.2 Layout Example .................................................... 60
13 Device and Documentation Support ................. 61
13.1
13.2
13.3
13.4
13.5
13.6
Device Support......................................................
Related Links ........................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
61
62
62
62
62
62
14 Mechanical, Packaging, and Orderable
Information ........................................................... 62
4 Revision History
Changes from Revision G (January 2015) to Revision H
Page
•
Changed Buffer Enable/Disable. .......................................................................................................................................... 48
•
Changed BUF_EN = 1 to 0. ................................................................................................................................................ 53
Changes from Revision F (March 2013) to Revision G
Page
•
Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1
•
Added footnote to INL, GE, and Crosstalk specifications. ..................................................................................................... 6
•
Changed tDOD1 specification. ................................................................................................................................................ 11
•
Deleted CH_STS and ADC_DOUTM from Compute the CRC... sentence.......................................................................... 38
•
Added sentence to the end of the RESET and RESTART section. ..................................................................................... 39
Changes from Revision E (March 2013) to Revision F
•
2
Page
Changed layout of National Data Sheet to TI format ........................................................................................................... 52
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SNAS521H – JULY 2011 – REVISED JANUARY 2016
5 Description (continued)
Another feature of the LMP9007x and LMP90080 is continuous background sensor diagnostics, allowing the
detection of open and short circuit conditions and out-of-range signals, without requiring user intervention,
resulting in enhanced system reliability.
Two sets of independent external reference voltage pins allow multiple ratiometric measurements. In addition,
two matched programmable current sources are available in the LMP90080/LMP90078 to excite external sensors
such as resistive temperature detectors and bridge sensors. Furthermore, seven GPIO pins are provided for
interfacing to external LEDs and switches to simplify control across an isolation barrier.
Collectively, these features make the LMP90080/LMP90079/LMP90078/LMP90077 complete analog front-ends
for low-power, precision sensor applications such as temperature, pressure, strain gauge, and industrial process
control. The LMP90080/LMP90079/LMP90078/LMP90077 are ensured over the extended temperature range of 40°C to +125°C and are available in a 28-pin package with an exposed pad.
6 Device Comparison Table
LM90xxx 16-BIT SENOR AFE FAMILY OF PRODUCTS
DEVICE NUMBER
CHANNEL CONFIGURATION
LMP90080
CURRENT SOURCES
4 Differential/7 Single-Ended
LMP90079
Yes
LMP90078
2 Differential/4 Single-Ended
LMP90077
Copyright © 2011–2016, Texas Instruments Incorporated
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SNAS521H – JULY 2011 – REVISED JANUARY 2016
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7 Pin Configuration and Functions
PWP Package
28-Pin HTSSOP
Top View
LMP90080/
LMP90079 only
VA
1
28
VIN0
2
27
D6 / DRDYB
D5
D4
VIO
VIN1
3
26
VIN2
4
25
VIN3
5
24
D3
VIN4
6
23
D2
22
D1
VIN5
7
VREFP1
8
21
D0
VREFN1
9
20
SDO/DRDYB
SDI
LMP900xx
VIN6/VREFP2
10
19
VIN7/VREFN2
11
18
SCLK
IB2
12
17
CSB
IB1
13
16
GND
XOUT
14
15
XIN/CLK
LMP90080/
LMP90078 only
Pin Functions
PIN
LMP90080
PIN NO.
LMP90079
PIN NO.
LMP90078
PIN NO.
LMP90077 PIN
NO.
TYPE
VA
1
1
1
1
Analog Supply
VIN0
2
2
2
2
VIN1
3
3
3
3
VIN2
4
4
4
4
VIN3
5
5
—
—
VIN4
6
6
—
—
VIN5
7
7
—
—
VIN3
—
—
5
5
VIN4
—
—
6
6
VIN5
—
—
7
7
VREFP1
8
8
8
VREFN1
9
9
VIN6 / VREFP2
10
VIN7 / VREFN2
NAME
FUNCTION
Analog power supply pin
Analog Input
Analog input pins
Analog Input
Analog input pins
No Connect
No connect: must be left
unconnected
8
Analog Input
Positive reference input
9
9
Analog Input
Negative reference input
10
10
10
Analog Input
Analog input pin or VREFP2
input
11
11
11
11
Analog Input
Analog input pin or VREFN2
input
IB2
12
—
12
—
IB1
13
—
13
—
Analog output
Excitation current sources for
external RTDs
IB2
—
12
—
12
IB1
—
13
—
13
XOUT
14
14
14
XIN / CLK
15
15
GND
16
CSB
17
SCLK
18
4
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No Connect
No connect: must be left
unconnected
14
Analog output
External crystal oscillator
connection
15
15
Analog input
External crystal oscillator
connection or external clock
input
16
16
16
Ground
17
17
17
Digital Input
Chip select bar
18
18
18
Digital Input
Serial clock
Power supply ground
Copyright © 2011–2016, Texas Instruments Incorporated
Product Folder Links: LMP90077 LMP90078 LMP90079 LMP90080
LMP90077, LMP90078, LMP90079, LMP90080
www.ti.com
SNAS521H – JULY 2011 – REVISED JANUARY 2016
Pin Functions (continued)
PIN
LMP90080
PIN NO.
LMP90079
PIN NO.
LMP90078
PIN NO.
LMP90077 PIN
NO.
TYPE
SDI
19
19
19
19
Digital Input
SDO / DRDYB
20
20
20
20
Digital Output
D0
21
21
21
21
D1
22
22
22
22
D2
23
23
23
23
D3
24
24
24
24
D4
25
25
25
25
D5
26
26
26
26
D6 / DRDYB
27
27
27
VIO
28
28
Thermal Pad
—
—
NAME
FUNCTION
Serial data input
Serial data output and data
ready bar
Digital IO
General purpose input/output
(GPIO) pins
27
Digital IO
General purpose input/output
pin or data ready bar
28
28
Digital Supply
Digital input/output supply pin
—
—
—
Leave the thermal pad floating
8 Specifications
8.1 Absolute Maximum Ratings
See
(1) (2) (3) (4)
.
MIN
MAX
Analog Supply Voltage, VA
–0.3
6.0
Digital I/O Supply Voltage, VIO
–0.3
6.0
Reference Voltage, VREF
–0.3
VA+0.3
Voltage on Any Analog Input Pin to GND (5)
–0.3
VA+0.3
Voltage on Any Digital Input PIN to GND (5)
–0.3
VIO+0.3
Voltage on SDO (5)
–0.3
VIO+0.3
Input Current at Any Pin (5)
5
Output Current Source or Sink by SDO
5
UNIT
V
mA
Total Package Input and Output Current
20
Junction Temperature (TJMAX)
150
°C
150
°C
Storage Temperature (Tstg)
(1)
(2)
(3)
(4)
(5)
–65
All voltages are measured with respect to GND, unless otherwise specified
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
For soldering specifications see product folder at http://www.ti.com and http://www.ti.com/lit/SNOA549
If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
When the input voltage (VIN) exceeds the power supply (VIN < GND or VIN > VA), the current at that pin must be limited to 5mA and
VIN has to be within the Absolute Maximum Rating for that pin. The 20 mA package input current rating limits the number of pins that
can safely exceed the power supplies with current flow to four pins.
8.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2500
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±1250
Machine models (MM)
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
Copyright © 2011–2016, Texas Instruments Incorporated
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8.3 Recommended Operating Conditions
Analog Supply Voltage, VA
Digital I/O Supply Voltage, VIO
MIN
MAX
2.85
5.5
2.7
Full Scale Input Range, VIN
5.5
V
±VREF / PGA
Reference Voltage, VREF
0.5
VA
Temperature Range for Electrical Characteristics
–40
125
Operating Temperature Range
–40
125
Junction to Ambient Thermal Resistance (RθJA) (1)
(1)
UNIT
41
°C
°C/W
The maximum power dissipation is a function of TJ(MAX) AND RθJA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(MAX) - TA) / RθJA.
8.4 Thermal Information
LMP900xx
THERMAL METRIC (1)
RθJA
(1)
HTSSOP (28 PINS)
Junction-to-ambient thermal resistance
41
UNIT
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
8.5 Electrical Characteristics
Unless otherwise noted, the key for the condition is (VA = VIO = VREF) / ODR (SPS) / buffer / calibration / gain . The typical
values apply for TA = +25°C.
PARAMETER
n
Resolution
ENOB /
NFR
Effective Number of
Bits and Noise Free
Resolution
ODR
Output Data Rates
INL
TEST CONDITIONS
3V / all / ON / OFF / all. Shorted input.
5V / all / ON / OFF / all. Shorted input.
Gain
FGA × PGA
Integral NonLinearity (1)
3V / 214.65 / ON / ON / 1
Total Noise
MIN
TYP
Offset Error
Bits
Bits
See Table 3
See Table 1
214.6
1
See Table 3
128
-1
± 0.5
+1
3V & 5V / 214.65 / ON / ON / 16
±1
µV
See Table 4
µV
3V & 5V / all / ON or OFF / ON / all
Below Noise
Floor (rms)
µV
3V / 214.65 / ON / ON / 128
(1)
6
1.22
9.52
µV
0.00838
0.70
µV
1.79
8.25
µV
0.0112
0.63
µV
100
nV/°C
3V & 5V / 214.65 / ON / ON / 1-8
3
nV/°C
3V & 5V / 214.65 / ON / OFF / 16
25
nV/°C
3V & 5V / 214.65 / ON / ON / 16
0.4
nV/°C
6
nV/°C
3V & 5V / 214.65 / ON / ON / 128
0.125
nV/°C
5V / 214.65 / ON / OFF / 1, TA = 150°C
2360
nV/1000 hours
5V / 214.65 / ON / ON / 1, TA = 150°C
3V & 5V / 214.65 / ON / ON / 1, TMIN ≤ TA ≤ TMAX
Gain Drift over
Temp (1)
LSB
5V / all / ON / OFF / all. Shorted input.
3V & 5V / 214.65 / ON / OFF / 128
Gain Error (1)
LSB
See Table 2
3V & 5V / 214.65 / ON or OFF/OFF/1-8
GE
SPS
3V / all / ON / ON / all. Shorted input.
5V / 214.65 / ON / ON / 128
Offset Drift over
Time (1)
Bits
1.6675
5V / 214.65 / ON / ON / 1
Offset Drift Over
Temp (1)
UNIT
See Table 1
3V / 214.65 / ON / ON / 1
OE
MAX
16
100
-80
nV/1000 hours
80
ppm
3V & 5V / 214.65 / ON / ON / 1
7
ppm
3V & 5V / 13.42 / ON / ON / 16
50
ppm
3V & 5V / 13.42 / ON / ON / 64
50
ppm
3V & 5V / 13.42 / ON / ON / 128
100
ppm
3V & 5V / 214.65 / ON / ON / all
0.5
ppm/°C
This parameter is specified by design and/or characterization and is not tested in production.
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Electrical Characteristics (continued)
Unless otherwise noted, the key for the condition is (VA = VIO = VREF) / ODR (SPS) / buffer / calibration / gain . The typical
values apply for TA = +25°C.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
5V / 214.65 / ON / OFF / 1, TA = 150°C
5.9
ppm/1000
hours
5V / 214.65 / ON / ON / 1, TA = 150°C
1.6
ppm/1000
hours
Gain Drift over Time (1)
CONVERTER CHARACTERISTICS
DC, 3V / 214.65 / ON / ON / 1,
TMIN ≤ TA ≤ TMAX
70
dB
DC, 3V / 214.65 / ON / ON / 1
CMRR
Input Common Mode
Rejection Ratio
Reference Common
Mode Rejection
DC, 5V / 214.65 / OFF / OFF / 1,
TMIN ≤ TA ≤ TMAX
117
dB
DC, 5V / 214.65 / OFF / OFF / 1
120
dB
50/60 Hz, 5V / 214.65 / OFF / OFF / 1
117
dB
VREF = 2.5V
101
dB
115
dB
112
dB
PSRR
Power Supply
Rejection Ratio
DC, 3V / 214.65 / ON / ON / 1
NMRR
Normal Mode
Rejection Ratio (1)
47 Hz to 63 Hz, 5V / 13.42 / OFF / OFF / 1
TMIN ≤ TA ≤ TMAX
95
3V / 214.65 / OFF / OFF / 1, TMIN ≤ TA ≤ TMAX
95
Cross-talk (1)
dB
90
75
DC, 5V / 214.65 / ON / ON / 1
dB
dB
3V / 214.65 / OFF / OFF / 1
5V / 214.65 / OFF / OFF / 1, TMIN ≤ TA ≤ TMAX
136
dB
95
dB
5V / 214.65 / OFF / OFF / 1
143
dB
POWER SUPPLY CHARACTERISTICS
VA
Analog Supply
Voltage
VIO
Digital Supply Voltage
Copyright © 2011–2016, Texas Instruments Incorporated
2.85
3.0
5.5
V
2.7
3.3
5.5
V
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Electrical Characteristics (continued)
Unless otherwise noted, the key for the condition is (VA = VIO = VREF) / ODR (SPS) / buffer / calibration / gain . The typical
values apply for TA = +25°C.
PARAMETER
TEST CONDITIONS
MIN
3V / 13.42 / OFF / OFF / 1, ext. CLK
TYP
3V / 13.42 / OFF / OFF / 1, ext. CLK,
TMIN ≤ TA ≤ TMAX
464
5V / 13.42 / OFF / OFF / 1, ext. CLK,
TMIN ≤ TA ≤ TMAX
600
3V / 13.42 / ON / OFF / 64, ext. CLK,
TMIN ≤ TA ≤ TMAX
690
5V / 13.42 / ON / OFF / 64, ext. CLK,
TMIN ≤ TA ≤ TMAX
1547
3V / 214.65 / ON / OFF / 64, int. CLK,
TMIN ≤ TA ≤ TMAX
Analog Supply
Current
1760
5V / 214.65 / ON / OFF / 64, int. CLK,
TMIN ≤ TA ≤ TMAX
826
3V / 214.65 / OFF / OFF / 1, int. CLK,
TMIN ≤ TA ≤ TMAX
941
5V / 214.65 / OFF / OFF / 1, int. CLK,
TMIN ≤ TA ≤ TMAX
Standby, 3V , int. CLK
3
Standby, 3V , ext. CLK
257
Standby, 5V, int. CLK
5
Standby, 3V, ext. CLK
300
Power-down, 3V, int/ext CLK
2.6
Power-down, 3V, int/ext CLK, TMIN ≤ TA ≤ TMAX
1100
µA
10
µA
µA
15
µA
µA
µA
4.6
Power-down, 5V, int/ext CLK, TMIN ≤ TA ≤ TMAX
µA
µA
5
Power-down, 5V, int/ext CLK
µA
µA
1000
5V / 214.65 / OFF / OFF / 1, int. CLK
µA
µA
2000
3V / 214.65 / OFF / OFF / 1, int. CLK
µA
µA
1700
5V / 214.65 / ON / OFF / 64, int. CLK
µA
µA
800
3V / 214.65 / ON / OFF / 64, int. CLK
µA
µA
700
5V / 13.42 / ON / OFF / 64, ext. CLK
µA
µA
555
3V / 13.42 / ON / OFF / 64, ext. CLK
UNIT
µA
500
5V / 13.42 / OFF / OFF / 1, ext. CLK
IVA
MAX
400
µA
µA
9
µA
VREFN + 0.5
VA
V
GND
VREFP 0.5
V
REFERENCE INPUT
VREFP
Positive Reference
VREFN
Negative Reference
VREF
Differential Reference
VREF = VREFP - VREFN
ZREF
Reference Impedance
3V / 13.42 / OFF / OFF / 1
10
MΩ
IREF
Reference Input
3V / 13.42 / ON or OFF /ON or OFF/all
±2
µA
CREFP
Capacitance of the
Positive Reference
gain = 1
(1)
6
pF
CREFN
Capacitance of the
Negative Reference
gain = 1 (1)
6
pF
ILREF
Reference Leakage
Current
Power-down
1
nA
0.5
VA
V
ANALOG INPUT
VINP
Positive Input
Gain = 1-8, buffer ON
GND + 0.1
VA - 0.1
V
Gain = 16 - 128, buffer ON
GND + 0.4
VA - 1.5
V
GND
VA
V
Gain = 1-8, buffer ON
GND + 0.1
VA - 0.1
V
Gain = 16 - 128, buffer ON
GND + 0.4
VA - 1.5
V
GND
VA
V
Gain = 1-8, buffer OFF
VINN
Negative Input
Gain = 1-8, buffer OFF
8
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Electrical Characteristics (continued)
Unless otherwise noted, the key for the condition is (VA = VIO = VREF) / ODR (SPS) / buffer / calibration / gain . The typical
values apply for TA = +25°C.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VIN
Differential Input
VIN = VINP - VINN
±VREF / PGA
ZIN
Differential Input
Impedance
ODR = 13.42 SPS
15.4
MΩ
CINP
Capacitance of the
Positive Input
4
pF
CINN
Capacitance of the
Negative Input
4
pF
IIN
Input Leakage Current
3V & 5V / 13.42 / ON / OFF / 1-8
500
pA
3V & 5V / 13.42 / ON / OFF / 16 - 128
100
pA
5V / 214.65 / OFF / OFF / 1
5V / 214.65 / OFF / OFF / 1
DIGITAL INPUT CHARACTERISTICS at VA = VIO = VREF = 3.0 V
VIH
Logical "1" Input
Voltage
VIL
Logical "0" Input
Voltage
IIL
Digital Input Leakage
Current
VHYST
Digital Input
Hysteresis
0.7 x VIO
V
-10
0.3 x VIO
V
+10
µA
0.1 x VIO
V
DIGITAL OUTPUT CHARACTERISTICS at VA = VIO = VREF = 3.0 V
VOH
Logical "1" Output
Voltage
Source 300 µA
VOL
Logical "0" Output
Voltage
Sink 300 µA
IOZH,
IOZL
TRI-STATE Leakage
Current
COUT
TRI-STATE
Capacitance
2.6
V
-10
See (1)
0.4
V
10
µA
5
pF
0, 100, 200,
300, 400, 500,
600, 700, 800,
900, 1000
µA
EXCITATION CURRENT SOURCES CHARACTERISTICS (LMP90080/LMP90078 ONLY)
IB1, IB2
Excitation Current
Source Output
VA = VREF = 3V
IB1/IB2 Tolerance
VA = VREF = 3V, TMIN ≤ TA ≤ TMAX
IB1/IB2 Output
Compliance Range
VA = 3.0V & 5.0V, IB1/IB2 = 100 µA to 1000 µA
IB1/IB2 Regulation
VA = 5.0V, IB1/IB2 = 100 µA to 1000 µA
IB1/IB2 Drift
7%
VA = VREF = 5V
VA = VREF = 5V, TMIN ≤ TA ≤ TMAX
IBTC
2.5%
-7%
0.2%
-3.5%
3.5%
VA - 0.8
0.07
V
%/V
VA = 3.0V
95
ppm/°C
VA = 5.0V
60
ppm/°C
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Electrical Characteristics (continued)
Unless otherwise noted, the key for the condition is (VA = VIO = VREF) / ODR (SPS) / buffer / calibration / gain . The typical
values apply for TA = +25°C.
PARAMETER
TEST CONDITIONS
MIN
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 100 µA
TYP
1.53%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 200 µA
0.22%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 200 µA, TMIN ≤ TA ≤ TMAX
1%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 300 µA
0.2%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 300 µA, TMIN ≤ TA ≤ TMAX
0.85%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 400 µA
0.15%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 400 µA, TMIN ≤ TA ≤ TMAX
0.8%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 500 µA
IB1/IB2 Matching
0.14%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 500 µA, TMIN ≤ TA ≤ TMAX
0.7%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 600 µA
0.13%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 600 µA, TMIN ≤ TA ≤ TMAX
0.7%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 700 µA
0.075%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 700 µA, TMIN ≤ TA ≤ TMAX
0.65%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 800 µA
0.085%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 800 µA, TMIN ≤ TA ≤ TMAX
0.6%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 900 µA
0.11%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 900 µA,TMIN ≤ TA ≤ TMAX
0.55%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 1000 µA
0.11%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 1000 µA, TMIN ≤ TA ≤ TMAX
IBMTC
IB1/IB2 Matching Drfit
UNIT
0.34%
3V & 5V / 214.65 / OFF / OFF / 1,
IB1/IB2 = 100 µA, TMIN ≤ TA ≤ TMAX
IBMT
MAX
0.45%
VA = 3.0V & 5.0V, IB1/IB2 = 100 µA to 1000 µA
2
ppm/°C
INTERNAL/EXTERNAL CLK
CLKIN
Internal Clock
Frequency
CLKEXT
External Clock
Frequency
External Crystal
Frequency
893
See (1)
1.8
Input Low Voltage
0
Input High Voltage
1
Frequency
1.8
Start-up time
SCLK
10
3.5717
7.2
MHz
V
V
7.2
MHz
10
MHz
7
Serial Clock
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3.5717
kHz
ms
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SNAS521H – JULY 2011 – REVISED JANUARY 2016
8.6 Timing Requirements
Unless otherwise noted, specified limits apply for VA = VIO = 3 V. The typical values apply for TA = 25°C.
MIN
NOM
fSCLK
tCH
SCLK High time
tCL
SCLK Low time
See Figure 1.
MAX
UNIT
10
MHz
0.4 / fSCLK
ns
0.4 / fSCLK
ns
8.7 Timing Requirements - CSB Timing
MIN
tCSSU
CSB Setup time prior to an SCLK
rising edge
See Figure 2.
tCSH
CSB Hold time after the last rising
edge of SCLK
See Figure 3.
NOM
MAX
UNIT
5
ns
6
ns
8.8 Timing Requirements - SCLK and SDI Timing
MIN
tCLKR
SCLK Rise time
tCLKF
SCLK Fall time
tDISU
SDI Setup time prior to an SCLK rising
edge
tDIH
SDI Hold time after an SCLK rising
edge
NOM
See Figure 4.
See Figure 5.
MAX
UNIT
1.15
ns
1.15
ns
5
ns
6
ns
8.9 Timing Requirements - SDO Timing With DOD1
MIN
tDOA
SDO Access time after an SCLK falling edge
tDOH
SDO Hold time after an SCLK falling edge
tDOD1
SDO Disable time after the rising edge of CSB
NOM
MAX
UNIT
35
See Figure 6.
ns
5
ns
See Figure 7.
27
ns
8.10 Timing Requirements - SDO Timing with DOD2
MIN
tDOD2
SDO Disable time after either edge of SCLK
NOM
See Figure 8 and Figure 9.
MAX
UNIT
27
ns
8.11 Timing Requirements - SDO and DRDYB Timing
MIN
tDOE
SDO Enable time from the falling
edge of the 8th SCLK
tDOR
SDO Rise time (1)
tDOF
SDO Fall time (1)
tDRDYB
(1)
NOM
See Figure 10.
UNIT
35
7
See Figure 11.
Data Ready Bar pulse at every
1/ODR second
MAX
ODR ≤ 13.42 SPS
13.42 < ODR ≤ 214.65 SPS
ns
ns
7
ns
64
µs
4
µs
This parameter is specified by design and/or characterization and is not tested in production.
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CSB
tCH
SCLK
1
2
3
1/fSCLK
tCL
4
5
6
7
8
9
10
11
12
13
14
15
16
n
17
INST2
SDI
MSB
LSB
DRDYB is driving the pin
SDO is driving the pin
Data Byte (s)
SDO/
DRDYB
MSB
LSB
...
Figure 1. Timing Diagram
CSB
CSB
0.3VIO
tCSHmin
tCSSUmin
0.7VIO
SCLK
SCLK
Figure 2. CBS Setup Time
0.7VIO
Figure 3. CBS Hold Time
0.9VIO
0.9VIO
0.7VIO
SCLK
SCLK
0.1VIO
0.1VIO
t CLKR
t DISU
t CLKF
SDI
Figure 4. SCLK Rise and Fall Time
t DIH
0.7VIO
DB
0.3VIO 0.3VIO
0.7VIO
Figure 5. SCLK Setup and Hold Time
0.7VIO
SCLK
0.3VIO
CSB
t DOH
t DOD1
t DOA
0.9VIO
SDO
0.7VIO
0.7VIO
0.3VIO
0.3VIO
DB
DB
Figure 6. SDO Enable Time
12
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SDO
DB0
0.1VIO
Figure 7. SDO Rise and Fall Time
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0.7VIO
SCLK
SCLK
tDOD2 (optional,
0.3 VIO
SW_OFF_TRG = 1)
t DOD2
0.9 VIO
0.9VIO
DB0
SDO
DB0
SDO
0.1 VIO
0.1VIO
Figure 8. SDO Disable Time
8
SCLK
Figure 9. SDO Rise and Fall Time
SDO
tDOE
0.1VIO
0.1VIO
t DOR
0.7VIO
SDO
0.9VIO
0.9VIO
9
0.3VIO
t DOF
DB7
0.3VIO
Figure 10. SDO Enable Time
Figure 11. SDO Rise and Fall Time
Table 1. ENOB (Noise Free Resolution) vs Sampling Rate and Gain At VA = VIO = VREF = 3V
ODR (SPS)
GAIN
1
2
4
8
16
32
64
128
1.6775
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
3.355
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (14.5)
6.71
16 (16)
16 (16)
16 (16)
16 (15.5)
16 (16)
16 (16)
16 (15)
16 (14.5)
13.42
16 (16)
16 (16)
16 (15.5)
16 (15)
16 (16)
16 (15.5)
16 (15)
16 (14)
26.83125
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
16 (15)
53.6625
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15)
16 (14.5)
107.325
16 (16)
16 (16)
16 (16)
16 (15.5)
16 (16)
16 (15.5)
16 (14.5)
16 (14)
214.65
16 (16)
16 (16)
16 (15.5)
16 (15)
16 (16)
16 (15)
16 (14.5)
16 (13.5)
Table 2. RMS Noise (mV) vs Sampling Rate and Gain At VA = VIO = VREF = 3V
ODR (SPS)
GAIN OF THE ADC
1
2
4
8
16
32
64
128
1.6775
3.08
1.90
1.53
1.27
0.23
0.21
0.15
0.14
3.355
4.56
2.70
2.21
1.67
0.34
0.27
0.24
0.26
6.71
6.15
4.10
3.16
2.39
0.51
0.40
0.37
0.35
13.42
8.60
5.85
4.29
3.64
0.67
0.54
0.51
0.49
26.83125
3.35
2.24
1.65
1.33
0.33
0.27
0.26
0.25
53.6625
4.81
3.11
2.37
1.90
0.44
0.39
0.37
0.36
107.325
6.74
4.51
3.38
2.66
0.63
0.54
0.52
0.49
214.65
9.52
6.37
4.72
3.79
0.90
0.79
0.72
0.70
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Table 3. ENOB (Noise Free Resolution) vs Sampling Rate and Gain At VA = VIO = VREF = 5V
SPS
GAIN OF THE ADC
1
2
4
8
16
32
64
128
1.6775
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
3.355
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
6.71
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15)
13.42
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
16 (15)
26.83125
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
53.6625
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15)
107.325
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15.5)
16 (14.5)
214.65
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (16)
16 (15)
16 (14)
Table 4. RMS Noise (mV) vs. Sampling Rate and Gain At VA = VIO = VREF = 5V
SPS
GAIN OF THE ADC
1
2
4
8
16
32
64
128
1.6775
2.68
1.65
1.24
1.00
0.22
0.19
0.17
0.16
3.355
3.86
2.36
1.78
1.47
0.34
0.27
0.22
0.22
6.71
5.23
3.49
2.47
2.09
0.44
0.34
0.30
0.32
13.42
7.94
5.01
3.74
2.94
0.61
0.50
0.45
0.43
26.83125
2.90
1.86
1.34
1.08
0.29
0.24
0.23
0.23
53.6625
4.11
2.60
1.90
1.50
0.39
0.35
0.32
0.31
107.325
5.74
3.72
2.72
2.11
0.56
0.48
0.46
0.44
214.65
8.25
5.31
3.82
2.97
0.79
0.68
0.64
0.63
14
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8.12 Typical Characteristics
250
50
230
30
VOUT ( V)
VOUT ( V)
Unless otherwise noted, specified limits apply for VA = VIO = VREF = 3.0 V. The maximum and minimum values apply for TA
= TMIN to TMAX; the typical values apply for TA = 25°C.
210
190
170
10
-10
-30
VA = 3V
VA = 3V
150
-50
0
200
400
600
TIME (ms)
800
1000
Figure 12. Noise Measurement Without Calibration
at Gain = 1
1400
1400
1200
1200
1000
1000
800
600
400
400
200
200
190
210
230
1000
VA = 3V
0
-50
250
-30
-10
VOUT (PV)
10
30
50
VOUT (PV)
Figure 14. Histogram Without Calibration
at Gain = 1
Figure 15. Histogram With Calibration
at Gain = 1
40
20
35
15
30
10
VOUT ( V)
VOUT ( V)
800
800
600
170
400
600
TIME (ms)
1600
VA = 3V
0
150
200
Figure 13. Noise Measurement With Calibration
at Gain = 1
COUNT
COUNT
1600
0
25
20
15
10
5
0
-5
-10
5
-15
VA = 3V
0
0
200
VA = 3V
-20
400
600
TIME (ms)
800
1000
Figure 16. Noise Measurement Without Calibration
at Gain = 8
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0
200
400
600
TIME (ms)
800
1000
Figure 17. Noise Measurement With Calibration
at Gain = 8
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Typical Characteristics (continued)
Unless otherwise noted, specified limits apply for VA = VIO = VREF = 3.0 V. The maximum and minimum values apply for TA
= TMIN to TMAX; the typical values apply for TA = 25°C.
2000
2000
VA = 3V
1500
COUNT
COUNT
1500
1000
500
-5
5
15
25
0
-25
35
-15
-5
5
15
25
35
VOUT (PV)
VOUT (#V)
Figure 18. Histogram Without Calibration
at Gain = 8
Figure 19. Histogram With Calibration
at Gain = 8
4
4
3
3
2
2
VOUT ( V)
VOUT ( V)
-15
1
0
-1
-2
1
0
-1
-2
-3
-3
VA = 3V
-4
0
200
VA = 3V
-4
400
600
TIME (ms)
800
1000
Figure 20. Noise Measurement Without Calibration
at Gain = 128
3000
0
2500
2000
2000
1500
1000
500
500
-3
-1
1
3
5
800
1000
VA = 3V
1500
1000
-5
400
600
TIME (ms)
3000
VA = 3V
2500
0
200
Figure 21. Noise Measurement With Calibration
at Gain = 128
COUNT
COUNT
1000
500
0
-25
16
VA = 3V
0
-5
-3
-1
1
3
5
VOUT (PV)
VOUT (PV)
Figure 22. Histogram Without Calibration
at Gain = 128
Figure 23. Histogram With Calibration
at Gain = 128
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Typical Characteristics (continued)
Unless otherwise noted, specified limits apply for VA = VIO = VREF = 3.0 V. The maximum and minimum values apply for TA
= TMIN to TMAX; the typical values apply for TA = 25°C.
12
12
VA = 3V
VA = 5V
VA = 3V
VA = 5V
10
RMS NOISE (#V)
RMS NOISE (#V)
10
8
6
4
2
0
8
6
4
2
1
2
4
8
16
32
0
64 128
1
2
4
8
GAIN
16
32
GAIN
Figure 24. Noise vs. Gain Without Calibration
at ODR = 13.42 SPS
Figure 25. Noise vs. Gain With Calibration
at ODR = 13.42 SPS
12
12
VA = 3V
VA = 5V
VA = 3V
VA = 5V
10
RMS NOISE (#V)
RMS NOISE (#V)
10
8
6
4
2
8
6
4
2
0
0
1
2
4
8
16
32
64 128
1
2
4
8
GAIN
16
32
64 128
GAIN
Figure 26. Noise vs. Gain Without Calibration
at ODR = 214.65 SPS
Figure 27. Noise vs. Gain With Calibration
at ODR = 214.65 SPS
300
2.0
VA = 3V
250
200
VA = 5V
150
VA = 3V
100
50
0
OFFSET VOLTAGE ( V)
OFFSET VOLTAGE ( V)
64 128
1.5
1.0
0.5
VA = 5V
0.0
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 28. Offset Error vs. Temperature Without Calibration
at Gain = 1
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-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 29. Offset Error vs. Temperature With Calibration
at Gain = 1
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Typical Characteristics (continued)
Unless otherwise noted, specified limits apply for VA = VIO = VREF = 3.0 V. The maximum and minimum values apply for TA
= TMIN to TMAX; the typical values apply for TA = 25°C.
0.4
20
VA = 5V
15
10
VA = 3V
5
OFFSET VOLTAGE (uV)
OFFSET VOLTAGE ( V)
25
0
VA = 3V
0.0
VA = 5V
-0.2
-0.4
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 30. Offset Error vs. Temperature Without Calibration
at Gain = 8
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 31. Offset Error vs. Temperature With Calibration
at Gain = 8
40
150
VA = 5V
140
130
VA = 3V
GAIN ERROR (ppm)
160
GAIN ERROR (ppm)
0.2
120
20
VA = 5V
0
-20
VA = 3V
110
-40
-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 32. Gain Error vs. Temperature Without Calibration
at Gain = 1
-40 -20
Figure 33. Gain Error vs. Temperature With Calibration
at Gain = 1
-100
-20
VA = 3V
-40
-120
VA = 3V
-130
-140
VA = 5V
-150
-160
-40 -20
GAIN ERROR (ppm)
GAIN ERROR (ppm)
-110
-60
-80
VA = 5V
-100
-120
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 34. Gain Error vs. Temperature Without Calibration
at Gain = 8
18
0 20 40 60 80 100 120
TEMPERATURE (°C)
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-40 -20
0 20 40 60 80 100 120
TEMPERATURE (°C)
Figure 35. Gain Error vs. Temperature With Calibration
at Gain = 8
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Typical Characteristics (continued)
0
0
-20
-20
-40
-40
GAIN (dB)
GAIN (dB)
Unless otherwise noted, specified limits apply for VA = VIO = VREF = 3.0 V. The maximum and minimum values apply for TA
= TMIN to TMAX; the typical values apply for TA = 25°C.
-60
-80
-60
-80
1.7 SPS
3.4 SPS
6.7 SPS
13.4 SPS
-100
26.83 SPS
53.66 SPS
107.33 SPS
214.65 SPS
-100
-120
-120
1
10
FREQUENCY (Hz)
100
10
Figure 36. Digital Filter Frequency Response
100
FREQUENCY (Hz)
1k
Figure 37. Digital Filter Frequency Response
INL (ppm of FSR)
10
5
0
-5
VA = 5V, 13.4 SPS
-10
-5 -4 -3 -2 -1 0 1
VIN (V)
2
3
4
5
Figure 38. INL at Gain = 1
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9 Detailed Description
9.1 Overview
Throughout this datasheet, the LMP90080/LMP90079/LMP90078/LMP90077 will be referred to as the
LMP900xx.
The LMP900xx is a low-power 16-Bit ΣΔ ADC with 4 fully differential/7 single-ended analog channels for the
LMP90080/LMP90079 and 2 full differential/4 single-ended for the LMP90078/LMP90077. Its serial data output is
two’s complement format. The output data rate (ODR) ranges from 1.6775 SPS to 214.65 SPS.
The serial communication for LMP900xx is SPI, a synchronous serial interface that operates using 4 pins: chip
select bar (CSB), serial clock (SCLK), serial data in (SDI), and serial data out / data ready bar (SDO/DRDYB).
True continuous built-in offset and gain background calibration is also available to improve measurement
accuracy. Unlike other ADCs, the LMP900xx’s background calibration can run without heavily impacting the input
signal. This unique technique allows for positive as well as negative gain calibration and is available at all gain
settings.
The registers can be found in the Register Maps section, and a detailed description of the LMP900xx are
provided in the following sections.
9.2 Functional Block Diagram
Chip Configurable
LMP900xx
Channel Configurable
Fixed
VA
EXC.
CURRENT
IB1
LMP90080/
LMP90078 only
VIO
VA
EXC.
CURRENT
Open/Short
Sensor Diag.
IB2
POR
SERIAL I/F
CONTROL
&
CALIBRATION
DATA PATH
VIN0
VIN1
VIN3
LMP90080/
LMP90079 only
VIN4
VIN5
BACKGROUND
CALIBRATION
INPUT MUX
VIN2
FGA
16x
PGA
1x, 2x,
4x, 8x
SCLK
SDI
SDO/DRDYB
CSB
BUFF
16 bit 6'
Module
VIN6/VREFP2
DIGITAL
FILTER
VIN7/VREFN2
CLK
MUX
VREF
Ext. Clk
Detect
Internal
CLK
MUX
GPIO
GND
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VREFP1
VREFN1
XOUT
CLK/ D6/
XIN DRDYB
D0
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9.3 Feature Description
9.3.1 Calibration
As seen in Figure 39, there are two types of calibration: background calibration and system calibration. These
calibrations are further described in the next sections.
Calibration
Background
calibration
Correction
System
calibration
Estimation
Offset
Gain
Figure 39. Types of Calibration
9.3.1.1 Background Calibration
Background calibration is the process of continuously determining and applying the offset and gain calibration
coefficients to the output codes to minimize the LMP900xx’s offset and gain errors. Background calibration is a
feature built into the LMP900xx and is automatically done by the hardware without interrupting the input signal.
Four differential channels, CH0-CH3, each with its own gain and ODRs, can be calibrated to improve the
accuracy.
9.3.1.1.1 Types of Background Calibration:
Figure 39 also shows that there are two types of background calibration:
Type 1: Correction the process of continuously determining and applying the offset and gain calibration
coefficients to the output codes to minimize the LMP900xx’s offset and gain errors.
This method keeps track of changes in the LMP900xx's gain and offset errors due to
changes in the operating condition such as voltage, temperature, or time.
Type 2: Estimation the process of determining and continuously applying the last known offset and gain
calibration coefficients to the output codes to minimize the LMP900xx’s offset and gain errors.
The last known offset or gain calibration coefficients can come from two sources. The first
source is the default coefficient which is pre-determined and burnt in the device’s nonvolatile memory. The second source is from a previous calibration run of Type 1: Correction.
The benefits of using Type 2 calibration is a higher throughput, lower power consumption, and slightly better
noise. The exact savings would depend on the number of channels being scanned, and the ODR and gain of
each channel.
9.3.1.1.2 Using Background Calibration:
There are four modes of background calibration, which can be programmed using the BGCALCN bits. They are
as follows:
• BgcalMode0: Background Calibration OFF
• BgcalMode1: Offset Correction / Gain Estimation
• BgcalMode2: Offset Correction / Gain Correction. Follow Figure 40 to set other appropriate registers when
using this mode.
• BgcalMode3: Offset Estimation / Gain Estimation
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Feature Description (continued)
Is the channel
gain 8 16x?
No
Set
BGCALCN = 10b to
operate the device in
BgcalMode2
Yes
Set CH_SCAN_SEL = 10b to
operate the device in
ScanMode2. Set FIRST_CH &
LAST_CH accordingly.
Correct FGA
error?
No
Set
FGA_BGCAL = 1 to
correct for FGA error
using the last known
coefficients.
Yes
Set FGA_BGCAL = 0 (default)
Figure 40. BgcalMode2 Register Settings
If operating in BgcalMode2, four channels (with the same ODR) are being converted, and FGA_BGCAL = 0
(default), then the ODR is reduced by:
1. 0.19% of 1.6775 SPS
2. 0.39% of 3.355 SPS
3. 0.78% of 6.71 SPS
4. 1.54% of 13.42 SPS
5. 3.03% of 26.83125 SPS
6. 5.88% of 53.6625 SPS
7. 11.11% of 107.325 SPS
8. 20% of 214.65 SPS
9.3.1.2 System Calibration
The LMP900xx provides some unique features to support easy system offset and system gain calibrations.
The System Calibration Offset Registers (CHx_SCAL_OFFSET) hold the System Calibration Offset Coefficients
in 16-bit, two's complement binary format. The System Calibration Gain Registers (CHx_SCAL_GAIN) hold the
System Calibration Gain Coefficient in 16-bit, 1.15, unsigned, fixed-point binary format. For each channel, the
System Calibration Offset coefficient is subtracted from the conversion result prior to the division by the System
Calibration Gain coefficient.
A data-flow diagram of these coefficients can be seen in Figure 41.
Uncalibrated
VIN
±
OFFSET
[CHx_SCAL_
OFFSET]
y
Calibrated
ADC_DOUT
GAIN
[CHx_SCAL_
GAIN]
Figure 41. System Calibration Data-Flow Diagram
There are four distinct sets of System Calibration Offset and System Calibration Gain Registers for use with
CH0-CH3. CH4-CH6 reuse the registers of CH0-CH2, respectively.
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Feature Description (continued)
The LMP900xx provides two system calibration modes that automatically fill the Offset and Gain coefficients for
each channel. These modes are the System Calibration Offset Coefficient Determination mode and the System
Calibration Gain Coefficient Determination mode. The System Calibration Offset Coefficient Determination mode
must be entered prior to the System Calibration Gain Coefficient Determination mode, for each channel.
The system zero-scale condition is a system input condition (sensor loading) for which zero (0x0000) systemcalibrated output code is desired. It may not, however, cause a zero input voltage at the input of the ADC.
The system reference-scale condition is usually the system full-scale condition in which the system's input (or
sensor's loading) would be full-scale and the desired system-calibrated output code would be 0x8000 (unsigned
16-bit binary). However, system full-scale condition need not cause full-scale input voltage at the input of the
ADC.
The system reference-scale condition is not restricted to just the system full-scale condition. In fact, it can be any
arbitrary fraction of full-scale (up to 1.25 times) and the desired system-calibrated output code can be any
appropriate value (up to 0xA000). The CHx_SCAL_GAIN register must be written with the desired systemcalibrated output code (default:0x8000) before entering the System Calibration Gain Coefficient Determination
mode. This helps in in-place system calibration.
9.3.1.2.1 System Calibration Offset Coefficient Determination Mode
Below are the detailed procedures for using the System Calibration Offset Coefficient Determination and System
Calibration Gain Coefficient Determination modes.
1. Apply system zero-scale condition to the channel (CH0/CH1/CH2/CH3).
2. Enter the System Calibration Offset Coefficient Determination mode by programming 0x1 in the SCALCN
register.
3. LMP900xx starts a fresh conversion at the selected output data rate for the selected channel. At the end of
the conversion, the CHx_SCAL_OFFSET register is filled-in with the System Calibration Offset coefficient.
4. The System Calibration Offset Coefficient Determination mode is automatically exited.
5. The computed calibration coefficient is accurate only to the effective resolution of the device and will
probably contain some noise. The noise factor can be minimized by computing over many times, averaging
(externally) and putting the resultant value back into the register. Alternatively, select the output data rate to
be 26.83 SPS or 1.67 SPS.
9.3.1.2.2 System Calibration Gain Coefficient Determination Mode
1. Repeat the System Calibration Offset Coefficient Determination to calibrate the System offset for the
channel.
2. Apply the system reference-scale condition to the channel CH0/CH1/CH2/CH3.
3. In the CHx_SCAL_GAIN register, program the expected (desired) system-calibrated output code for this
condition in 16-bit unsigned format.
4. Enter the System Calibration Gain Coefficient Determination mode by programming 0x3 in the SCALCN
register.
5. LMP900xx starts a fresh conversion at the selected output data rate for the channel. At the end of the
conversion, the CHx_SCAL_GAIN is filled-in (or overwritten) with the System Calibration Gain coefficient.
6. The System Calibration Gain Coefficient Determination mode is automatically exited.
7. The computed calibration coefficient is accurate only to the effective resolution of the device and will
probably contain some noise. The noise factor can be minimized by computing over many times, averaging
(externally) and putting the resultant value back into the register. Alternatively, select the output data rate to
be 26.83 SPS or 1.67 SPS.
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Feature Description (continued)
9.3.1.2.3 Post-Calibration Scaling
LMP900xx allows scaling (multiplication and shifting) for the System Calibrated result. This eases downstream
processing, if any. Multiplication is done using the System Calibration Scaling Coefficient in the
CHx_SCAL_SCALING register and shifting is done using the System Calibration Bits Selector in the
CHx_SCAL_BITS_SELECTOR register.
The System Calibration Bits Selector value should ideally be the logarithm (to the base 2) of the System
Calibration Scaling Coefficient value.
There are four distinct sets of System Calibration Scaling and System Calibration Bits Selector Registers for use
with CH0-CH3. CH4-CH6 reuse the registers of CH0-CH2, respectively.
A data-flow diagram of these coefficients can be seen in Figure 42.
System Calibrated
Code[15:0]
X
[20:0]
SCALING
[CHx_SCAL_
SCALING]
Scaled and Calibrated
ADC_DOUT
BITS SELECTOR
[CHx_SCAL_
BITS_SELECTOR]
Figure 42. Post-Calibration Scaling Data-Flow Diagram
9.3.2 True Continuous Background Calibration
The LMP90080/LMP90079/LMP90078/LMP90077 feature a 16-bit ΣΔ core with continuous background
calibration to compensate for gain and offset errors in the ADC, virtually eliminating any drift with time and
temperature. The calibration is performed in the background without user or ADC input interruption, making it
unique in the industry and eliminating down time associated with field calibration required with other solutions.
Having this continuous calibration improves performance over the entire life span of the end product.
9.3.3 Continuous Background Sensor Diagnostics
Sensor diagnostics are also performed in the background, without interfering with signal path performance,
allowing the detection of sensor shorts, opens, and out-of-range signals, which vastly improves system reliability.
In addition, the fully flexible input multiplexer described below allows any input pin to be connected to any ADC
input channel providing additional sensor path diagnostic capability.
9.3.4 Flexible Input MUX Channels
The flexible input MUX allows interfacing to a wide range of sensors such as thermocouples, RTDs, thermistors,
and bridge sensors. The LMP90080/LMP90079’s multiplexer supports 4 differential channels while the
LMP90078/LMP90077 supports 2. Each effective input voltage that is digitized is VIN = VINX – VINY, where x and y
are any input. In addition, the input multiplexer of the LMP90080/LMP90079 also supports 7 single-ended
channels (LMP90078/LMP90077 supports 4), where the common ground is any one of the inputs.
9.3.5 Programmable Gain Amplifiers (FGA & PGA)
The LMP90080/LMP90079/LMP90078/LMP90077 contain an internal 16x fixed gain amplifier (FGA) and a 1x,
2x, 4x, or 8x programmable gain amplifier (PGA). This allows accurate gain settings of 1x, 2x, 4x, 8x, 16x, 32x,
64x, or 128x through configuration of internal registers. Having an internal amplifier eliminates the need for
external amplifiers that are costly, space consuming, and difficult to calibrate.
9.3.6 Excitation Current Sources (IB1 & IB2) - LMP90080/LMP90078
Two matched internal excitation currents, IB1 and IB2, can be used for sourcing currents to a variety of sensors.
The current range is from 100 µA to 1000 µA in steps of 100 µA.
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Feature Description (continued)
9.3.7 Signal Path
9.3.7.1 Reference Input (VREF)
The differential reference voltage VREF (VREFP – VREFN) sets the range for VIN.
The muxed VREF allows the user to choose between VREF1 or VREF2 for each channel. This selection can be
made by programming the VREF_SEL bit in the CHx_INPUTCN registers (CHx_INPUTCN: VREF_SEL). The default
mode is VREF1. If VREF2 is used, then VIN6 and VIN7 cannot be used as inputs because they share the same pin.
Refer to VREF for VREF applications information.
9.3.7.2 Flexible Input MUX (VIN)
LMP900xx provides a flexible input MUX as shown in Figure 43. The input that is digitized is VIN = VINP – VINN;
where VINP and VINN can be any available input.
The digitized input is also known as a channel, where CH = VIN = VINP – VINN. Thus, there are a maximum of 4
differential channels: CH0, CH1, CH2, and CH3 for the LMP90080/LMP90079. The LMP90078/LMP90077 has 2
differential channels: CH0 and CH1 because it does not have the VIN3, VIN4, and VIN5 pins.
LMP900xx can also be configured single-ended, where the common ground is any one of the inputs. There are a
maximum of 7 single-ended channels: CH0, CH1, CH2, CH3, CH4, CH5, and CH6 for the LMP90080/LMP90079
and 4: CH0, CH1, CH2, CH3 for the LMP90078/LMP90077.
The input MUX can be programmed in the CHx_INPUTCN registers. For example on the LMP90080, to program
CH0 = VIN = VIN4 – VIN1, go to the CH0_INPUTCN register and set:
1. VINP = 0x4
2. VINN = 0x1
VREFP1
VIN0
VIN1
VIN2
VIN3*
VINP
+
+
-
ADC
BUFF
FGA
VINN
+
-
-
VIN4*
VIN5*
VIN6/VREFP2
VIN7/VREFN2
VREFN1
* VIN3, VIN4, VIN5 are only available for LMP90080 and LMP90079
Figure 43. Simplified VIN Circuitry
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Feature Description (continued)
9.3.7.3
Selectable Gains (FGA and PGA)
LMP900xx provides two types of gain amplifiers: a fixed gain amplifier (FGA) and a programmable gain amplifier
(PGA). FGA has a fixed gain of 16x or it can be bypassed, while the PGA has programmable gain settings of 1x,
2x, 4x, or 8x.
Total gain is defined as FGA x PGA. Thus, LMP900xx provides gain settings of 1x, 2x, 4x, 8x, 16x, 32x, 64x, or
128x with true continuous background calibration.
The gain is channel specific, which means that one channel can have one gain, while another channel can have
the same or a different gain.
The gain can be selected by programming the CHx_CONFIG: GAIN_SEL bits.
9.3.7.4 Buffer (BUFF)
There is an internal unity gain buffer that can be included or excluded from the signal path. Including the buffer
provides a high input impedance but increases the power consumption.
When gain ≥ 16, the buffer is automatically included in the signal path. When gain < 16, including or excluding
the buffer from the signal path can be done by programming the CHX_CONFIG: BUF_EN bit.
9.3.7.5 Internal/External CLK Selection
LMP900xx allows two clock options: internal CLK or external CLK (crystal (XTAL) or clock source).
There is an “External Clock Detection” mode, which detects the external XTAL if it is connected to XOUT and
XIN. When operating in this mode, the LMP900xx shuts off the internal clock to reduce power consumption.
Below is a flow chart to help set the appropriate clock registers.
Clock
Options
Internal CLK
External CLK Source
External
XTAL
LMP900xx will use the
internal clock
No
Is there a XTAL
connected to XIN and
XOUT?
Connect a XTAL
to XIN and XOUT
Connect an external
CLK source to the
XIN/CLK pin
LMP900xx will
automatically detect
and use the XTAL if
CLK_EXT_DET = 0
(default)
LMP900xx will
automatically use the
external CLK source
Yes
Set CLK_EXT_DET = 1 to
E\SDVV WKH ³([WHUQDO-Clock
'HWHFWLRQ´ PRGH
Set CLK_SEL = 0 to select
the internal clock
Figure 44. CLK Register Settings
The recommended value for the external CLK is discussed in the next sections.
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Feature Description (continued)
9.3.7.6 Programmable ODRS
If using the internal CLK or external CLK of 3.5717 MHz, then the output date rates (ODR) can be selected
(using the ODR_SEL bit) as:
1. 13.42/8 = 1.6775 SPS
2. 13.42/4 = 3.355 SPS
3. 13.42/2 = 6.71SPS
4. 13.42 SPS
5. 214.65/8 = 26.83125 SPS
6. 214.65/4 = 53.6625 SPS
7. 214.65/2 = 107.325 SPS
8. 214.65 SPS (default)
If the internal CLK is not being used and the external CLK is not 3.5717 MHz, then the ODR will be different. If
this is the case, use the equation below to calculate the new ODR values.
ODR_Base1 = (CLKEXT) / (266,240)
ODR_Base2 = (CLKEXT) / (16,640)
ODR1 = (ODR_Base1) / n, where n = 1,2,4,8
ODR2 = (ODR_Base2) / n, where n = 1,2,4,8
(1)
(2)
(3)
(4)
For example, a 3.6864 MHz XTAL or external clock has the following ODR values:
ODR_Base1 = (3.6864 MHz) / (266,240) = 13.85 SPS
ODR_Base2 = (3.6864 MHz) / (16,640) = 221.54 SPS
ODR1 = (13.85 SPS) / n = 13.85, 6.92, 3.46, 1.73 SPS
ODR2 = (221.54 SPS) / n = 221.54, 110.77, 55.38, 27.69 SPS
(5)
(6)
(7)
(8)
The ODR is channel specific, which means that one channel can have one ODR, while another channel can
have the same or a different ODR.
Note that these ODRs are meant for a single channel conversion; the ODR needs to be divided by n for n
channels scanning. For example, if the ADC were running at 214.65 SPS and four channels are being scanned,
then the ODR per channel would be 214.65/4 = 53.6625 SPS.
9.3.7.7 Digital Filter
The LMP900xx has a fourth order rotated sinc filter that is used to configure various ODRs and to reject power
supply frequencies of 50Hz and 60Hz. The 50/60 Hz rejection is only effective when the device is operating at
ODR ≤ 13.42 SPS. If the internal CLK or the external CLK of 3.5717 MHz is used, then the LMP900xx will have
the frequency response shown in Figure 45 through Figure 49.
0
0
6.71 SPS
13.42 SPS
-20
-20
-40
-40
GAIN (dB)
GAIN (dB)
1.6775 SPS
3.355 SPS
-60
-60
-80
-80
-100
-100
-120
-120
0
12
24
36
48
60
72
84
96
108
120
FREQUENCY (Hz)
Figure 45. Digital Filter Response, 1.6775 SPS and 3.355
SPS
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0
12
24
36
48
60
72
84
96
108
120
FREQUENCY (Hz)
Figure 46. Digital Filter Response, 6.71 SPS and 13.42 SPS
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Feature Description (continued)
-60
0
13.42 SPS
26.83125 SPS
53.6625 SPS
-70
-40
GAIN (dB)
GAIN (dB)
-80
-90
-100
-80
-110
-120
-120
45
47
49
51
53
55
57
59
61
63
65
0
200
400
600
800
FREQUENCY (Hz)
1000
1200
1400
1600
1800
2000
FREQUENCY (Hz)
Figure 47. Digital Filter Response at 13.42 SPS
Figure 48. Digital Filter Response, 26.83125 SPS and
53.6625 SPS
0
0
107.325 SPS
214.65 SPS
Crystal = 3.5717 MHz
Crystal = 3.6864 MHz
-20
-40
GAIN (dB)
GAIN (dB)
-40
-80
-60
-80
-100
-120
-140
-120
0
200
400
600
800
1000
1200
1400
1600
1800
40
2000
45
FREQUENCY (Hz)
Figure 49. Digital Filter Response 107.325 SPS and 214.65
SPS
50
55
60
FREQUENCY (Hz)
65
70
Figure 50. Digital Filter Response for a 3.5717 MHz Versus
3.6864 MHz XTAL
If the internal CLK is not being used and the external CLK is not 3.5717 MHz, then the filter response would be
the same as the response shown above, but the frequency will change according to the equation:
fNEW = [(CLKEXT) / 256 ] x (fOLD / 13.952k)
(9)
Using Equation 9, an example of the filter response for a 3.5717 MHz XTAL versus a 3.6864 MHz XTAL can be
seen in Figure 50.
9.3.7.8 GPIO (D0–D6)
Pins D0-D6 are general purpose input/output (GPIO) pins that can be used to control external LEDs or switches.
Only a high or low value can be sourced to or read from each pin.
Figure 51 shows a flowchart how these GPIOs can be programmed.
inputs
Pins
D0 ± D6 =
outputs
Set
GPIO_DIRCNx = 0
Set
GPIO_DIRCNx = 1
Read the
GPIO_DAT: Dx bit to
determine if Dx is
high or low, where
0 7 x 7 6.
Write to GPIO_DAT: Dx bit
to drive Dx high or low,
where 0 7 x 7 6.
Figure 51. GPIO Register Settings
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9.4 Device Functional Modes
9.4.1 Channels Scan Mode
There are four scan modes. These scan modes are selected using the CH_SCAN: CH_SCAN_SEL bit. The first
scanned channel is FIRST_CH, and the last scanned channel is LAST_CH; they are both located in the
CH_SCAN register.
The CH_SCAN register is double buffered. That is, user inputs are stored in a slave buffer until the start of the
next conversion during which time they are transferred to the master buffer. Once the slave buffer is written,
subsequent updates are disregarded until a transfer to the master buffer happens. Hence, it may be appropriate
to check the CH_SCAN_NRDY bit before programming the CH_SCAN register.
9.4.1.1 ScanMode0: Single-Channel Continuous Conversion
LMP900xx continuously converts the selected FIRST_CH.
Do not operate in this scan mode if gain ≥ 16 and the LMP900xx is running in background calibration modes
BgcalMode1 or BgcalMode2. If this is the case, then it is more suitable to operate the device in ScanMode2
instead.
9.4.1.2 ScanMode1: Multiple-Channels Single Scan
LMP900xx converts one or more channels starting from FIRST_CH to LAST_CH, and then enters the stand-by
state.
9.4.1.3 ScanMode2: Multiple-Channels Continuous Scan
LMP900xx continuously converts one or more channels starting from FIRST_CH to LAST_CH, and then it
repeats this process.
9.4.1.4 ScanMode3: Multiple-Channels Continuous Scan with Burnout Currents
This mode is the same as ScanMode2 except that the burnout current is provided in a serially scanned fashion
(injected in a channel after it has undergone a conversion). Thus it avoids burnout current injection from
interfering with the conversion result for the channel.
The sensor diagnostic burnout currents are available for all four scan modes. The burnout current is further gated
by the BURNOUT_EN bit for each channel. ScanMode3 is the only mode that scans multiple channels while
injecting burnout currents without interfering with the signal. This is described in details in Burnout Currents.
9.4.2 Sensor Interface
The LMP90080/LMP90078 contains two excitation currents (IB1 & IB2) for sourcing external sensors, and the
LMP900xx contain two burnout currents for sensor diagnostics. They are described in the next sections.
9.4.2.1 IB1 & IB2 - Excitation Currents (LMP90080/LMP90078)
IB1 and IB2 can be used for providing currents to external sensors, such as RTDs or bridge sensors. 100µA to
1000µA, in steps of 100µA, can be sourced by programming the ADC_AUXCN: RTD_CUR_SEL bits.
Refer to 3–Wire RTD to see how IB1 and IB2 can be used to source a 3-wire RTD.
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Device Functional Modes (continued)
9.4.2.2 Burnout Currents
As shown in Figure 52, the LMP900xx contains two internal 10 µA burnout current sources, one sourcing current
from VA to VINP, and the other sinking current from VINN to ground. These currents are used for sensor
diagnostics and can be enabled for each channel using the CHx_INPUTCN: BURNOUT_EN bit.
Burnout
Current = 10 PA
VIN0
VIN1
VIN2
VIN3
VINP
VINN
VIN4
VIN5
VIN6/VREFP2
VIN7/VREFN2
Burnout
Current = 10 PA
* VIN3, VIN4, VIN5 are only available for LMP90080 and LMP90079
Figure 52. Burnout Currents
9.4.2.2.1 Burnout Current Injection
Burnout currents are injected differently depending on the channel scan mode selected.
When BURNOUT_EN = 1 and the device is operating in ScanMode0, 1, or 2, the burnout currents are injected
into all the channels for which the BURNOUT_EN bit is selected. This will cause problems and hence in this
mode, more than one channel should not have its BURNOUT_EN bit selected. Also, the burnout current will
interfere with the signal and introduce a fixed error depending on the particular external sensor.
When BURNOUT_EN = 1 and the device is operating in ScanMode3, burnout currents are injected into the last
sampled channel on a cyclical basis (Figure 53). In this mode, burnout currents injection is truly done in the
background without affecting the accuracy of the on-going conversion. Operating in this mode is recommended.
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Device Functional Modes (continued)
Burnout Currents
BURNOUT_EN
CH0 is being sampled
CH0
CH1
CH2
CH3
BURNOUT_EN
CH1 is being sampled
CH0
CH1
CH2
CH3
BURNOUT_EN
CH2 is being sampled
CH0
CH1
CH2
CH3
BURNOUT_EN
CH3 is being sampled
CH0
CH1
CH2
CH3
Figure 53. Burnout Currents Injection for Scanmode3
9.4.2.3 Sensor Diagnostic Flags
Burnout currents can be used to verify that an external sensor is still operational before attempting to make
measurements on that channel. A non-operational sensor means that there is a possibility the connection
between the sensor and the LMP900xx is open circuited, short circuited, shorted to VA or GND, overloaded, or
the reference may be absent. The sensor diagnostic flags diagram can be seen in Figure 54.
RAILS_FLAG
Generator
RAILS_FLAG
Overflow detection
OFLO_FLAGS
VINP
FGA
VINN
BUFF
Modulator
ADC_DOUT
Filter
RAILS_FLAG
Generator
RAILS_FLAG
SENDIAG_THLDH
and SENDIAG_THLDL
SHORT_THLD_
FLAG
Figure 54. Sensor Diagnostic Flags Diagram
The sensor diagnostic flags are located in the SENDIAG_FLAGS register and are described in further details
below.
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Device Functional Modes (continued)
9.4.2.3.1 SHORT_THLD_FLAG
The short circuit threshold flag is used to report a short-circuit condition. It is set when the output voltage (VOUT)
is within the absolute Vthreshold. Vthreshold can be programmed using the 8-bit SENDIAG_THLDH register.
For example, assume VREF = 5V, gain = 1, SENDIAG_THLD = 0xDA (218d). In this case, Vthreshold can be
calculated as:
Vthreshold = [(SENDIAG_THLD)(2)(VREF)] / [(Gain)(216)]
Vthreshold = [(218)(2)(5V)] / [(1)(216)]
Vthreshold = 33.3 mV
(10)
(11)
(12)
When (-33.3mV) ≤ VOUT ≤ (33.3mV), then SHORT_THLD_FLAG = 1; otherwise, SHORT_THLD_FLAG = 0.
9.4.2.3.2 RAILS_FLAG
The rails flag is used to detect if one of the sampled channels is within 50mV of the rails potential (VA or VSS).
This can be further investigated to detect an open-circuit or short-circuit condition. If the sampled channel is near
a rail, then RAILS_FLAG = 1; otherwise, RAILS_FLAG = 0.
9.4.2.3.3 POR_AFT_LST_RD
If POR_AFT_LST_READ = 1, then there was a power-on reset since the last time the SENDIAG_FLAGS register
was read. This flag's status is cleared when this bit is read, unless this bit is set again on account of another
power-on-reset event in the intervening period.
9.4.2.3.4 OFLO_FLAGS
OFLO_FLAGS is used to indicate whether the modulator is over-ranged or under-ranged. The following
conditions are possible:
1. OFLO_FLAGS = 0x0: Normal Operation
2. OFLO_FLAGS = 0x1: The differential input is more than (±VREF/Gain) but is not more than ±(1.3*VREF/Gain)
to cause a modulator over-range.
3. OFLO_FLAGS = 0x2: The modulator was over-ranged towards +VREF/Gain.
4. OFLO_FLAGS = 0x3: The modulator was over-ranged towards −VREF/Gain.
The condition of OFLO_FLAGS = 10b or 11b can be used in conjunction with the RAILS_FLAG to determine the
fault condition.
9.4.2.3.5 SAMPLED_CH
These three bits show the channel number for which the ADC_DOUT and SENDIAG_FLAGS are available. This
does not necessarily indicate the current channel under conversion because the conversion frame and
computation of results from the channels are pipelined. That is, while the conversion is going on for a particular
channel, the results for the previous conversion (of the same or a different channel) are available.
9.5 Programming
9.5.1 Serial Digital Interface
A synchronous 4-wire serial peripheral interface (SPI) provides access to the internal registers of LMP900xx via
CSB, SCLK, SDI, SDO/DRDYB.
9.5.1.1 Register Address (ADDR)
All registers are memory-mapped. A register address (ADDR) is composed of an upper register address (URA)
and lower register address (LRA) as shown in Table 5. For example, ADDR 0x3A has URA=0x3 and LRA=0xA.
Table 5. ADDR Map
32
BIT
[6:4]
[3:0]
Name
URA
LRA
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9.5.1.2
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Register Read/Write Protocol
Figure 55 shows the protocol how to write to or read from a register.
Transaction 1 sets up the upper register address (URA) where the user wants to start the register-write or
register-read.
Transaction 2 sets the lower register address (LRA) and includes the Data Byte(s), which contains the incoming
data from the master or outgoing data from the LMP900xx.
Examples of register-reads or register-writes can be found in Register Read/Write Examples.
Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Instruction Byte 1 (INST1)
Upper Address Byte (UAB)
[7:0]
[7:3]
[2:0]
RA/WAB
0x0
Upper Register
Address (URA)
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
Data Byte (s)
7
[6:5]
4
[3:0]
[N:0]
R/WB
SZ
0
Lower Register
Address (LRA)
Data Byte (s)
R/WB = Read/Write Data
0: Write Data
1: Read Data
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 55. Register Read/Write Protocol
9.5.1.3 Streaming
When writing/reading 3+ bytes, the user must operate the device in Normal Streaming mode or Controlled
Streaming mode. In the Normal Streaming mode, which is the default mode, data runs continuously starting from
ADDR until CSB deasserts. This mode is especially useful when programming all the configuration registers in a
single transaction. See the Normal Streaming Example section for an example of the Normal Streaming mode.
In the Controlled Streaming mode, data runs continuously starting from ADDR until the data has run through all
(STRM_RANGE + 1) registers. For example, if the starting ADDR is 0x1C, STRM_RANGE = 5, then data will be
written to or read from the following ADDRs: 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21. Once the data reaches ADDR
0x21, LMP900xx will wrap back to ADDR 0x1C and repeat this process until CSB deasserts. See the Controlled
Streaming Example section for an example of the Controlled Streaming mode.
If streaming reaches ADDR 0x7F, then it will wrap back to ADDR 0x00. Furthermore, reading back the Upper
Register Address after streaming will report the Upper Register Address at the start of streaming, not the Upper
Register Address at the end of streaming.
To stream, write 0x3 to INST2’s SZ bits as seen in Figure 55. To select the stream type, program the
SPI_STREAMCN: STRM_TYPE bit. The STRM_RANGE can also be programmed in the same register.
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9.5.1.4 CSB – Chip Select Bar
An SPI transaction begins when the master asserts (active low) CSB and ends when the master deasserts
(active high) CSB. Each transaction might be separated by a subsequent one with a CSB deassertion, but this is
optional. Once CSB is asserted, it must not pulse (deassert and assert again) during a (desired) transaction.
CSB can be grounded in systems where LMP900xx is the only SPI slave. This frees the software from handling
the CSB. Care has to be taken to avoid any false edge on SCLK, and while operating in this mode, the streaming
transaction should not be used because exiting from this mode can only be done through a CSB deassertion.
9.5.1.5 SPI Reset
SPI Reset resets the SPI-Protocol State Machine by monitoring the SDI for at least 73 consecutive 1's at each
SCLK rising edge. After an SPI Reset, SDI is monitored for a possible Write Instruction at each SCLK rising
edge.
SPI Reset will reset the Upper Address Register (URA) to 0, but the register contents are not reset.
By default, SPI reset is disabled, but it can be enabled by writing 0x01 to SPI Reset Register (ADDR 0x02).
9.5.1.6 DRDYB - Data Ready Bar
DRDYB is a signal generated by the LMP900xx that indicates a fresh conversion data is available in the
ADC_DOUT registers.
DRDYB is automatically asserted every (1/ODR) second as seen in Figure 56. Before the next assertion, DRDYB
will pulse for tDRDYB second. The value for tDRDYB can be found in Timing Requirements.
1/ODR
DRDYB:
tDRDYB
...
SDO:
Figure 56. DRDYB Behavior
If ADC_DOUT is being read while a new ADC_DOUT becomes available, then the ADC_DOUT that is being
read is still valid (Figure 57). DRDYB will still be deasserted every 1/ODR second, but a consecutive read on the
ADC_DOUT register will fetch the newly converted data available.
1/ODR
D6 = drdyb
1/ODR
ADC
Data 1
ADC
Data 2
Valid
ADC_DOUT
(ADC Data 2)
Valid
ADC_DOUT
(ADC Data 1)
MSB
SDO
LSB
MSB
LSB
Figure 57. DRDYB Behavior For An Incomplete ADC_DOUT Reading
DRDYB can also be accessed via registers using the DT_AVAIL_B bit. This bit indicates when fresh conversion
data is available in the ADC_DOUT registers. If new conversion data is available, then DT_AVAIL_B = 0;
otherwise, DT_AVAIL_B = 1.
A complete reading for DT_AVAIL_B occurs when the MSB of ADC_DOUTH is read out. This bit cannot be reset
even if REG_AND_CNV_RST = 0xC3.
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9.5.1.6.1 DrdybCase1: Combining SDO/DRDYB with SDO_DRDYB_DRIVER = 0x00
uC
LMP900xx
SCLK
SCLK
CSB
CSB
SDI
MOSI
SDO/
DRDYB
MISO
INT
Figure 58. DrdybCase1 Connection Diagram
As shown in Figure 58, the DRDYB signal and SDO can be multiplexed on the same pin as their functions are
mostly complementary. In fact, this is the default mode for the SDO/DRDYB pin.
Figure 59 shows a timing protocol for DrdybCase1. In this case, start by asserting CSB first to monitor a DRDYB
assertion. When the DRDYB signal asserts, begin writing the Instruction Bytes (INST1, UAB, INST2) to read from
or write to registers. Note that INST1 and UAB are omitted from the figure below because this transaction is only
required if a new UAB needs to be implemented.
While the CSB is asserted, DRDYB is driving the SDO/DRDYB pin unless the device is reading data, in which
case, SDO will be driving the pin. If CSB is deasserted, then the SDO/DRDYB pin is High-Z.
CSB
tCH
SCLK
1
2
3
1/fSCLK
tCL
4
5
6
7
8
9
10
11
12
13
14
15
16
n
17
INST2
SDI
MSB
LSB
DRDYB is driving the pin
SDO is driving the pin
Data Byte (s)
SDO/
DRDYB
MSB
LSB
...
Figure 59. Timing Protocol for DrdybCase1
9.5.1.6.2 DrdybCase2: Combining SDO/DRDYB with SDO_DRDYB_DRIVER = 0x03
SDO/DRDYB can be made independent of CSB by setting SDO_DRDYB_DRIVER = 0x03 in the SPI Handshake
Control register. In this case, DRDYB will drive the pin unless the device is reading data, independent of the
state of CSB. SDO will drive the pin when CSB is asserted and the device is reading data.
With this scheme, one can use SDO/DRDYB as a true interrupt source, independent of the state of CSB. But this
scheme can only be used when the LMP900xx is the only device connected to the master's SPI bus because the
SDO/DRDYB pin will be DRDYB even when CSB is deasserted.
The timing protocol for this case can be seen in Figure 60. When DRDYB asserts, assert CSB to start the SPI
transaction and begin writing the Instruction Bytes (INST1, UAB, INST2) to read from or write to registers.
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CSB
tCH
SCLK
1
1/fSCLK
tCL
4
5
6
7
8
9
10
11
12
13
14
15
16
n
17
INST2
SDI
MSB
LSB
DRDYB is driving the pin
SDO is driving the pin
Data Byte (s)
SDO/
DRDYB
MSB
LSB
...
Figure 60. Timing Protocol For DrdybCase2
9.5.1.6.3 DrdybCase3: Routing DRDYB to D6
LMP900xx
uC
SCLK
SCLK
CSB
CSB
SDI
MOSI
SDO
MISO
D6 = DRDYB
Interrupt
Figure 61. DrdybCase3 Connection Diagram
The DRDYB signal can be routed to pin D6 by setting SPI_DRDYB_D6 high and SDO_DRDYB_DRIVER to 0x4.
This is the behavior for DrdybCase3 as shown in Figure 61.
The timing protocol for this case can be seen in Figure 62. Since DRDYB is separated from SDO, it can be
monitored using the interrupt or polling method. If polled, the DRDYB signal needs to be polled faster than tDRDYB
to detect a DRDYB assertion. When DRDYB asserts, assert CSB to start the SPI transaction and begin writing
the Instruction Bytes (INST1, UAB, INST2) to read from or write to registers.
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CSB
SCLK
1
2
3
4
5
6
7
9
8
10
11
12
13
14
15
16
17
n
INST2
SDI
MSB
LSB
Drdyb = D6
...
Data Byte (s)
High-Z
SDO
MSB
LSB
Figure 62. Timing Protocol for DrdybCase3
9.5.1.7 Data Only Read Transaction
In a data only read transaction, one can directly access the data byte(s) as soon as the CSB is asserted without
having to send any instruction byte. This is useful as it brings down the latency as well as the overhead
associated with the instruction byte (as well as the Upper Address Byte, if any).
In order to use the data only transaction, the device must be placed in the data first mode. The following table
lists transaction formats for placing the device in and out of the data first mode and reading the mode status.
Table 6. Data First Mode Transactions
BIT[7]
BITS[6:5]
BIT[4]
BITS[3:0]
DATA BYTES
Enable Data First Mode Instruction
1
11
1
1010
None
Disable Data First Mode Instruction
1
11
1
1011
None
Read Mode Status Transaction
1
00
1
1111
One
Note that while being in the data first mode, once the data bytes in the data only read transaction are sent out,
the device is ready to start on any normal (non-data-only) transaction including the Disable Data First Mode
Instruction. The current status of the data first mode (enabled/disabled status) can be read back using the Read
Mode Status Transaction. This transaction consists of the Read Mode Status Instruction followed by a single
data byte (driven by the device). The data first mode status is available on bit [1] of this data byte.
The data only read transaction allows reading up to eight consecutive registers, starting from any start address.
Usually, the start address will be the address of the most significant byte of conversion data, but it could just as
well be any other address. The start address and number of bytes to be read during the data only read
transaction can be programmed using the DATA_ONLY_1 AND DATA_ONLY_2 registers respectively.
The upper register address is unaffected by a data only read transaction. That is, it retains its setting even after
encountering a data only transaction. The data only transaction uses its own address (including the upper
address) from the DATA_ONLY_1 register. When in the data first mode, the SCLK must stop high before
entering the Data Only Read Transaction; this transaction should be completed before the next scheduled
DRDYB deassertion.
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9.5.1.8 Cyclic Redundancy Check (CRC)
CRC can be used to ensure integrity of data read from LMP900xx. To enable CRC, set EN_CRC high. Once
CRC is enabled, the CRC value is calculated and stored in SPI_CRC_DAT so that the master device can
periodically read for data comparison. The CRC is automatically reset when CSB or DRDYB is deasserted.
The CRC polynomial is x8 + x5 + x4 + 1. The reset value of the SPI_CRC_DAT register is zero, and the final
value is ones-complemented before it is sent out. Note that CRC computation only includes the bits sent out on
SDO and does not include the bits of the SPI_CRC_DAT itself; thus it is okay to read SPI_CRC_DAT repeatedly.
The DRDYB signal normally deasserts (active high) every 1/ODR second. However, this behavior can be
changed so that DRDYB deassertion can occur after SPI_CRC_DAT is read, but not later than normal DRDYB
deassertion which occurs at every 1/ODR seconds. This is done by setting bit DRDYB_AFT_CRC high.
The timing protocol for CRC can be found in Figure 63.
1/ODR
1/ODR
Sampling CH0
Sampling CH1
D6 = drdyb
Reading
SPI_CRC_DAT
Reading
ADC_DOUT of CH0
SDO
LSB
MSB
MSB
LSB
Reading
SPI_CRC_DAT
Reading
ADC_DOUT of CH1
LSB
MSB
MSB
LSB
Figure 63. Timing Protocol for Reading SPI_CRC_DAT
If SPI_CRC_DAT read extends beyond the normal DRDYB deassertion at every 1/ODR seconds, then
CRC_RST has to be set in the SPI Data Ready Bar Control Register. This is done to avoid a CRC reset at the
DRDYB deassertion. Timing protocol for reading CRC with CRC_RST set is shown in Figure 64.
1/ODR
CH0
1/ODR
CH1
D6 = drdyb
Reading
ADC_DOUT of CH0
SDO
MSB
LSB
Reading
SPI_CRC_DAT
MSB
LSB
Reading
ADC_DOUT of CH1
MSB
LSB
Reading
SPI_CRC_DAT
MSB
LSB
Figure 64. Timing Protocol for Reading SPI_CRC_DAT Beyond Normal DRDYB Deassertion at Every
1/ODR Seconds
Follow the steps below to enable CRC:
1. Set SPI_CRC_CN = 1 (register 0x13, bit 4) to enable CRC.
2. Set DRDYB_AFT_CRC = 1 (register 0x13, bit 2) to dessert the DRDYB after CRC.
3. Compute the CRC externally, which should include ADC_DOUTH and ADC_DOUTL.
4. Collect the data and verify the reported CRC matches with the computed CRC (step above).
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9.5.2 RESET and RESTART
Writing 0xC3 to the REG_AND_CNV_RST field will reset the conversion and most of the programmable registers
to their default values. The only registers that will not be reset are the System Calibration Registers
(CHx_SCAL_OFFSET, CHx_SCAL_GAIN) and the DT_AVAIL_B bit.
If it is desirable to reset the System Calibration Coefficient Registers, then set RESET_SYSCAL = 1 before
writing 0xC3 to REG_AND_CNV_RST. If the device is operating in the “System Calibration Offset/Gain
Coefficient Determination” mode (SCALCN register), then write REG_AND_CNV_RST = 0xC3 twice to get out of
this mode.
After a register reset, any on-going conversions will be aborted and restarted. If the device is in the power-down
state, then a register reset will bring it out of the power-down state.
To restart a conversion, write 1 to the RESTART bit. This bit can be used to synchronize the conversion to an
external event.
After a restart conversion, the first sample is not valid. To restart with a valid first sample, issue a stand-by
command followed by an active command.
9.5.3 Register Read/Write Examples
9.5.3.1 Writing to Register Examples
Using the register read/write protocol shown in Figure 55, the following example shows how to write three data
bytes starting at register address (ADDR) 0x1F. After the last byte has been written to ADDR 0x21, deassert
CSB to end the register-write.
Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Instruction Byte 1 (INST1)
Upper Address Byte (UAB)
[7:0]
[7:3]
[2:0]
0x10
0x0
0x1
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Data Bytes
Instruction Byte 2 (INST2)
7
4
[6:5]
[3:0]
[23:0]
st
The 1 Data Byte will be written to ADDR 0x1F, the 2
0
0x2
0
R/WB = Read/Write Data
0: Write Data
1: Read Data
0xF
nd
Data Byte will
rd
be written to ADDR 0x20, and the 3 Data Byte will be written to ADR
0x21. After this process, deassert CSB.
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 65. Register-Write Example 1
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The next example shows how to write one data byte to ADDR 0x12. Since the URA for this example is the same
as the last example, transaction 1 can be omitted.
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
Data Byte (s)
7
[6:5]
4
[3:0]
[7:0]
0
0x00
0
0x2
One Data Byte will be written to ADDR 0x12. After this process, deassert CSB.
R/WB = Read/Write Data
0: Write Data
1: Read Data
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 66. Register-Write Example 2
9.5.3.2 Reading from Register Example
The following example shows how to read two bytes. The first byte will be read from starting ADDR 0x24, and
the second byte will be read from ADDR 0x25.
Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Instruction Byte 1 (INST1)
Upper Address Byte (UAB)
[7:0]
[7:3]
[2:0]
0x10
0x0
0x2
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
7
[6:5]
4
[3:0]
1
0x1
0
0x4
R/WB = Read/Write Data
0: Write Data
1: Read Data
Data Bytes
[15:0]
2 Data Bytes will be read from ADDR 0x24 and ADDR 0x25.
After this process, deassert CSB.
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 67. Register-Read Example
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9.5.4 Streaming Examples
9.5.4.1 Normal Streaming Example
This example shows how to write six data bytes starting at ADDR 0x28 using the Normal Streaming mode.
Because the default STRM_TYPE is the Normal Streaming mode, setting up the SPI_STREAMCN register can
be omitted.
Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Upper Address Byte (UAB)
Instruction Byte 1 (INST1)
[7:0]
[7:3]
[2:0]
0x10
0x0
0x2
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
7
[6:5]
4
Data Bytes
[3:0]
[47:0]
st
nd
The 1 Data Byte will be written to ADDR 0x28, the 2
0
0x3
0
R/WB = Read/Write Data
0: Write Data
1: Read Data
0x8
Data Byte will be
th
written to ADDR 0x29, etc. The last and 6 Data Byte will be written to
ADDR 0x2D. After this process, deassert CSB.
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 68. Normal Streaming Example
9.5.4.2 Controlled Streaming Example
This example shows how to read the 16-bit conversion data (ADC_DOUT) four times using the Controlled
Streaming mode. The ADC_DOUT registers consist of ADC_DOUTH at ADDR 0x1A and ADC_DOUTL at ADDR
0x1B.
The first step (Figure 69) sets up the SPI_STREAMCN register. This step enters the Controlled Streaming mode
by setting STRM_TYPE high in ADDR 0x03. Since two registers (ADDR 0x1A - 0x1B) need to be read, the
STRM_RANGE is 1.
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Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Instruction Byte 1 (INST1)
Upper Address Byte (UAB)
[7:0]
[7:3]
[2:0]
0x10
0x0
0x0
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
Data Byte (s)
7
[6:5]
4
[3:0]
[7:0]
0
0x0
0
0x3
1000_0001b
R/WB = Read/Write Data
0: Write Data
1: Read Data
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 69. Setting Up SPI_STREAMCN
The next step shows how to perform the Controlled Streaming mode so that the master device will read
ADC_DOUT from ADDR 0x1A and 0x1B, then wrap back to ADDR 0x1A, and repeat this process for four times.
After this process, deassert CSB to end the Controlled Streaming mode.
Transaction 1 ± URA Setup ± necessary only when the previous URA is different than the desired URA.
Instruction Byte 1 (INST1)
Upper Address Byte (UAB)
[7:0]
[7:3]
[2:0]
0x10
0x0
0x1
R/WB = Read/Write Address
0x10: Write Address
0x90: Read Address
Transaction 2 ± Data Access
Instruction Byte 2 (INST2)
7
[6:5]
4
[3:0]
1
0x3
0
0xA
R/WB = Read/Write Data
0: Write Data
1: Read Data
Data Byte (s)
[63:0]
Read ADC_DOUTH and ADC_DOUTL four times. After this process,
deassert CSB.
SZ = Size
0x0: 1 byte
0x1: 2 bytes
0x2: 3 bytes
0x3: Streaming ± 3+ bytes until CSB is de-asserted
Figure 70. Controlled Streaming Example
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9.6 Register Maps
1. If written to, RESERVED bits must be written to only 0 unless otherwise indicated.
2. Read back value of RESERVED bits and registers is unspecified and should be discarded.
3. Recommended values must be programmed and forbidden values must not be programmed where they are
indicated in order to avoid unexpected results.
4. If written to, registers indicated as Reserved must have the indicated default value as shown below. Any
other value can cause unexpected results.
Table 7. Register Map
REGISTER NAME
ADDR (URA & LRA)
TYPE
DEFAULT
RESETCN
Reset Control
0x00
WO
-
SPI_HANDSHAKECN
SPI Handshake Control
0x01
R/W
0x00
SPI_RESET
SPI Reset Control
0x02
R/W
0x00
SPI_STREAMCN
SPI Stream Control
0x03
R/W
0x00
Reserved
-
0x04 - 0x07
-
0x00
PWRCN
Power Mode Control and Status
0x08
RO & WO
0x00
DATA_ONLY_1
Data Only Read Control 1
0x09
R/W
0x1A
DATA_ONLY_2
Data Only Read Control 2
0x0A
R/W
0x02
ADC_RESTART
ADC Restart Conversion
0x0B
WO
-
Reserved
-
0x0C - 0x0D
-
0x00
GPIO_DIRCN
GPIO Direction Control
0x0E
R/W
0x00
GPIO_DAT
GPIO Data
0x0F
RO & WO
-
BGCALCN
Background Calibration Control
0x10
R/W
0x00
SPI_DRDYBCN
SPI Data Ready Bar Control
0x11
R/W
0x03
ADC_AUXCN
ADC Auxiliary Control
0x12
R/W
0x00
SPI_CRC_CN
CRC Control
0x13
R/W
0x02
SENDIAG_THLD
Sensor Diagnostic Threshold
0x14
R/W
0x00
Reserved
-
0x15-0x16
-
0x0000
SCALCN
System Calibration Control
0x17
R/W
0x00
ADC_DONE
ADC Data Available
0x18
RO
-
SENDIAG_FLAGS
Sensor Diagnostic Flags
0x19
RO
-
ADC_DOUT
Conversion Data 1 and 0
0x1A - 0x1B
RO
-
Reserved
-
0x1C
-
-
SPI_CRC_DAT
CRC Data
0x1D
RO & WO
-
CHANNEL CONFIGURATION REGISTERS (CH4 to CH6 for LMP90080/LMP90079 only)
CH_STS
Channel Status
0x1E
RO
0x00
CH_SCAN
Channel Scan Mode
0x1F
R/W
0x30
CH0_INPUTCN
CH0 Input Control
0x20
R/W
0x01
CH0_CONFIG
CH0 Configuration
0x21
R/W
0x70
CH1_INPUTCN
CH1 Input Control
0X22
R/W
0x13
CH1_CONFIG
CH1 Configuration
0x23
R/W
0x70
CH2_INPUTCN
CH2 Input Control
0x24
R/W
0x25
CH2_CONFIG
CH2 Configuration
0x25
R/W
0x70
CH3_INPUTCN
CH3 Input Control
0x26
R/W
0x37
CH3_CONFIG
CH3 Configuration
0x27
R/W
0x70
CH4_INPUTCN
CH4 Input Control
0x28
R/W
0x01
CH4_CONFIG
CH4 Configuration
0x29
R/W
0x70
CH5_INPUTCN
CH5 Input Control
0x2A
R/W
0x13
CH5_CONFIG
CH5 Configuration
0x2B
R/W
0x70
CH6_INPUTCN
CH6 Input Control
0x2C
R/W
0x25
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Register Maps (continued)
Table 7. Register Map (continued)
REGISTER NAME
ADDR (URA & LRA)
TYPE
DEFAULT
CH6_CONFIG
CH6 Configuration
0x2D
R/W
0x70
Reserved
-
0x2E - 0x2F
-
0x00
0x30 - 0x31
R/W
0x0000
0x32
-
0x00
SYSTEM CALIBRATION REGISTERS
CH0_SCAL_OFFSET
CH0 System Calibration Offset Coefficients
Reserved
-
CH0_SCAL_GAIN
CH0 System Calibration Gain Coefficients
0x33 - 0x34
R/W
0x8000
Reserved
-
0x35
-
0x00
CH0_SCAL_SCALING
CH0 System Calibration Scaling Coefficients
0x36
R/W
0x01
CH0_SCAL_BITS_
SELECTOR
CH0 System Calibration Bit Selector
0x37
R/W
0x00
CH1_SCAL_OFFSET
CH1 System Calibration Offset Coefficients
0x38 - 0x39
R/W
0x0000
Reserved
-
0x3A
-
0x00
CH1_SCAL_GAIN
CH1 System Calibration Gain Coefficient
0x3B - 0x3C
R/W
0x8000
Reserved
-
0x3D
-
0x00
CH1_SCAL_SCALING
CH1 System Calibration Scaling Coefficients
0x3E
R/W
0x01
0x3F
R/W
0x00
0x40 - 0x41
R/W
0x0000
CH1_SCAL_BITS_SELECT
CH1 System Calibration Bit Selector
OR
CH2_SCAL_OFFSET
CH2 System Calibration Offset Coefficients
Reserved
-
CH2_SCAL_GAIN
CH2 System Calibration Gain Coefficient
Reserved
-
CH2_SCAL_SCALING
CH2 System Calibration Scaling Coefficients
CH2_SCAL_BITS_
SELECTOR
CH2 System Calibration Bit Selector
CH3_SCAL_OFFSET
CH3 System Calibration Offset Coefficients
Reserved
-
CH3_SCAL_GAIN
CH3 System Calibration Gain Coefficient
Reserved
-
CH3_SCAL_SCALING
CH3 System Calibration Scaling Coefficients
CH3_SCAL_BITS_
SELECTOR
CH3 System Calibration Bit Selector
Reserved
-
0x42
-
0x00
0x43 - 0x44
R/W
0x8000
0x45
-
0x00
0x46
R/W
0x01
0x47
R/W
0x00
0x48 - 0x49
R/W
0x0000
0x4A
-
0x00
0x4B - 0x4C
R/W
0x8000
0x4D
-
0x00
0x4E
R/W
0x01
0x4F
R/W
0x00
0x50 - 0x7F
-
0x00
9.6.1 Power and Reset Registers
Table 8. RESTCN
RESET CONTROL (ADDRESS 0x00)
BIT
BIT SYMBOL
BIT DESCRIPTION
Register and Conversion Reset 0xC3: Register and conversion reset
[7:0] REG_AND_CNV_RST
44
Others: Neglected
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Table 9. SPI_RESET
SPI RESET CONTROL (ADDRESS 0x02)
BIT
BIT SYMBOL
[0]
SPI_RST
BIT DESCRIPTION
SPI Reset Enable
0x0 (default): SPI Reset Disabled
0x1: SPI Reset Enabled (1)
Table 10. PWRCN
POWER MODE CONTROL AND STATUS (ADDRESS 0x08)
BIT
BIT SYMBOL
[7:2] Reserved
BIT DESCRIPTION
Power Control
Write Only – power down mode control
0x0: Active Mode
0x1: Power-down Mode
[1:0] PWRCN
0x3: Stand-by Mode
Read Only – the present mode is:
0x0 (default): Active Mode
0x1: Power-down Mode
0x3: Stand-by Mode
(1)
Once written, the contents of this register are sticky. That is, the content of this register cannot be changed with subsequent write.
However, a Register reset clears the register as well as the sticky status.
9.6.2 ADC Registers
Table 11. ADC_RESTART
ADC RESTART CONVERSION (ADDRESS 0x0B)
BIT
BIT SYMBOL
[7:1] Reserved
0
RESTART
BIT DESCRIPTION
Restart conversion
1: Restart conversion.
Table 12. ADC_AUXCN
ADC AUXILIARY CONTROL (ADDRESS 0x12)
BIT
BIT SYMBOL
BIT DESCRIPTION
7
Reserved
-
6
RESET_SYSCAL
The System Calibration registers (CHx_SCAL_OFFSET and CHx_SCAL_GAIN) are:
0 (default): preserved even when "REG_AND_CNV_RST" = 0xC3.
1: reset by setting "REG_AND_CNV_RST" = 0xC3.
External clock detection
5
CLK_EXT_DET
0 (default): "External Clock Detection" is operational
1: "External-Clock Detection" is bypassed
Clock select – only valid if CLK_EXT_DET = 1
4
CLK_SEL
0 (default): Selects internal clock
1: Selects external clock
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Table 12. ADC_AUXCN (continued)
ADC AUXILIARY CONTROL (ADDRESS 0x12)
BIT
BIT SYMBOL
BIT DESCRIPTION
Selects RTD Current as follows:
0x0 (default): 0 µA
0x1: 100 µA
0x2: 200 µA
0x3: 300 µA
RTD_CUR_SEL (LMP90080
[3:0]
and LMP90078 only)
0x4: 400 µA
0x5: 500 µA
0x6: 600 µA
0x7: 700 µA
0x8: 800 µA
0x9: 900 µA
0xA: 1000 µA
Table 13. ADC_DONE
ADC DATA AVAILABLE (ADDRESS 0x18)
BIT
BIT SYMBOL
BIT DESCRIPTION
Data Available – indicates if new conversion data is available
0x00 − 0xFE: Available
[7:0] DT_AVAIL_B
0xFF: Not available
Table 14. ADC_DOUT
(1)
16-BIT CONVERSION DATA (TWO’S COMPLEMENT) (ADDRESS 0x1A - 0x1B)
ADDRESS
(1)
NAME
REGISTER DESCRIPTION
0x1A
ADC_DOUTH
ADC Conversion Data [15:8]
0x1B
ADC_DOUTL
ADC Conversion Data [7:0]
0x1C
Reserved
Reserved
Repeat reads of these registers are allowed as long as such reads are spaced apart by at least 72 µs.
9.6.3 Channel Configuration Registers
Table 15. CH_STS
CHANNEL STATUS (ADDRESS 0x1E)
BIT
BIT SYMBOL
BIT DESCRIPTION
[7:2] Reserved
Channel Scan Not Ready – indicates if it is okay to program CH_SCAN
1
CH_SCAN_NRDY
0: Update not pending, CH_SCAN register is okay to program
1: Update pending, CH_SCAN register is not ready to be programmed
Invalid or Repeated Read Status
0
INV_OR_RPT_RD_STS
0: ADC_DOUT just read was valid and hitherto unread
1: ADC_DOUT just read was either invalid (not ready) or there was a repeated read.
46
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Table 16. CH_SCAN
(1)
CHANNEL SCAN MODE (ADDRESS 0x1F)
BIT
BIT SYMBOL
BIT DESCRIPTION
Channel Scan Select
0x0 (default): ScanMode0: Single-Channel Continuous Conversion
[7:6] CH_SCAN_SEL
0x1: ScanMode1: One or more channels Single Scan
0x2: ScanMode2: One or more channels Continuous Scan
0x3: ScanMode3: One or more channels Continuous Scan with Burnout Currents
Last channel for conversion
0x0: CH0
0x1: CH1
LAST_CH (CH4 to CH6 for
[5:3] LMP90080 and LMP90079
only)
0x2: CH2
0x3: CH3
0x4: CH4
0x5: CH5
0x6 (default): CH6 (2)
Starting channel for conversion
0x0 (default): CH0
0x1: CH1
FIRST_CH (CH4 to CH6 for
[2:0] LMP90080 and LMP90079
only)
0x2: CH2
0x3: CH3
0x4: CH4
0x5: CH5
0x6: CH6 (3)
(1)
(2)
While writing to the CH_SCAN register, if 0x7 is written to FIRST_CH or LAST_CH the write to the entire CH_SCAN register is ignored.
LAST_CH cannot be smaller than FIRST_CH. For example, if LAST_CH = CH5, then FIRST_CH cannot be CH6. If 0x7 is written it is
ignored.
FIRST_CH cannot be greater than LAST_CH. For example, if FIRST_CH = CH1, then LAST_CH cannot be CH0. If 0x7 is written it is
ignored.
(3)
Table 17. CHx_INPUTCN
CHANNEL INPUT CONTROL (CH4 TO CH6 FOR LMP90080/LMP90079 ONLY)
REGISTER ADDRESS (HEX): CH0: 0x20, CH1: 0x22, CH2: 0x24, CH3: 0x26, CH4: 0x28, CH5: 0x2A, CH6: 0x2C
BIT
BIT SYMBOL
BIT DESCRIPTION
Enable sensor diagnostic
7
BURNOUT_EN
0 (default): Disable Sensor Diagnostics current injection for this Channel
1: Enable Sensor Diagnostics current injection for this Channel
Select the reference
6
VREF_SEL
0 (Default): Select VREFP1 and VREFN1
1: Select VREFP2 and VREFN2
Positive input select
0x0: VIN0
0x1: VIN1
0x2: VIN2
[5:3]
VINP
0x3: VIN3 (LMP90080/LMP90079 only)
0x4:VIN4 (LMP90080/LMP90079 only)
0x5:VIN5 (LMP90080/LMP90079 only)
0x6: VIN6
0x7: VIN7 (1)
(1)
To see the default values for each channel, refer to the table below.
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Table 17. CHx_INPUTCN (continued)
CHANNEL INPUT CONTROL (CH4 TO CH6 FOR LMP90080/LMP90079 ONLY)
REGISTER ADDRESS (HEX): CH0: 0x20, CH1: 0x22, CH2: 0x24, CH3: 0x26, CH4: 0x28, CH5: 0x2A, CH6: 0x2C
BIT
BIT SYMBOL
BIT DESCRIPTION
Negative input select
0x0: VIN0
0x1: VIN1
0x2: VIN2
[2:0]
VINN
0x3: VIN3 (LMP90080/LMP90079 only)
0x4:VIN4 (LMP90080/LMP90079 only)
0x5:VIN5 (LMP90080/LMP90079 only)
0x6: VIN6
0x7: VIN7 (1)
Table 18. Default VIN for CH0-CH6
VINP
VINN
CH0
VIN0
VIN1
CH1
VIN2
VIN3 (LMP90080/LMP90079 only)
CH2
VIN4 (LMP90080/LMP90079 only)
VIN5 (LMP90080/LMP90079 only)
CH3
VIN6
VIN7
CH4 (LMP90080/LMP90079 only)
VIN0
VIN1
CH5 (LMP90080/LMP90079 only)
VIN2
VIN3
CH6 (LMP90080/LMP90079 only)
VIN4
VIN5
Table 19. CHx_CONFIG
CHANNEL CONFIGURATION (CH4 TO CH6 LMP90080/LMP90079 ONLY)
REGISTER ADDRESS (HEX): CH0: 0x21, CH1: 0x23, CH2: 0x25, CH3: 0x27, CH4: 0x29, CH5: 0x2B, CH6: 0x2D
BIT
7
BIT SYMBOL
BIT DESCRIPTION
Reserved
ODR Select
0x0: 13.42 / 8 = 1.6775 SPS
0x1: 13.42 / 4 = 3.355 SPS
0x2: 13.42 / 2 = 6.71 SPS
[6:4] ODR_SEL
0x3: 13.42 SPS
0x4: 214.65 / 8 = 26.83125 SPS
0x5: 214.65 / 4 = 53.6625 SPS
0x6: 214.65 / 2 = 107.325 SPS
0x7(default): 214.65 SPS
Gain Select
0x0 (default): 1 (FGA OFF)
0x1: 2 (FGA OFF)
0x2: 4 (FGA OFF)
[3:1] GAIN_SEL
0x3: 8 (FGA OFF)
0x4: 16 (FGA ON)
0x5: 32 (FGA ON)
0x6: 64 (FGA ON)
0x7: 128 (FGA ON)
Enable/Disable the buffer
0
BUF_EN
0 (default): Exclude the buffer in the signal path
1: Include the buffer from the signal path (1)
(1)
48
When gain ≥ 16, the buffer is automatically included in the signal path irrespective of this bit.
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9.6.4 Calibration Registers
Table 20. BGCALCN
BACKGROUND CALIBRATION CONTROL (ADDRESS 0x10)
BIT
BIT SYMBOL
BIT DESCRIPTION
[7:2] Reserved
Background calibration control – selects scheme for continuous background calibration.
0x0 (default): BgcalMode0: Background Calibration OFF
[1:0] BGCALN
0x1: BgcalMode1: Offset Correction / Gain Estimation
0x2: BgcalMode2: Offset Correction / Gain Correction
0x3: BgcalMode3: Offset Estimation / Gain Estimation
Table 21. SCALCN
SYSTEM CALIBRATION CONTROL (ADDRESS 0x17)
BIT
BIT SYMBOL
BIT DESCRIPTION
[7:2] Reserved
System Calibration Control
When written, set SCALCN to:
0x0 (default): Normal Mode
0x1: “System Calibration Offset Coefficient Determination” mode
0x2: “System Calibration Gain Coefficient Determination” mode
[1:0] SCALCN
0x3: Reserved
When read, this bit indicates the system calibration mode is in:
0x0: Normal Mode
0x1: "System Calibration Offset Coefficient Determination" mode
0x2: "System Calibration Gain Coefficient Determination" mode
0x3: Reserved (1)
(1)
When read, this bit will indicate the current System Calibration status. Since this coefficient determination mode will only take 1
conversion cycle, reading this register will only return 0x00, unless this register is read within 1 conversion window.
Table 22. CHx_SCAL_OFFSET
CH0-CH3 SYSTEM CALIBRATION OFFSET REGISTERS (TWO'S-COMPLEMENT)
ADDR
NAME
DESCRIPTION
0x48
CHx_SCAL_OFFSETH
System Calibration Offset Coefficient Data [15:8]
0x49
CHx_SCAL_OFFSETM
System Calibration Offset Coefficient Data [7:0]
0x4A
Reserved
-
CH0
CH1
CH2
CH3
0x30
0x38
0x40
0x31
0x39
0x41
0x32
0x3A
0x42
Table 23. CHx_SCAL_GAIN
CH0-CH3 SYSTEM CALIBRATION GAIN REGISTERS (FIXED POINT 1.23 FORMAT)
ADDR
NAME
DESCRIPTION
0x4B
CHx_SCAL_GAINH
System Calibration Gain Coefficient Data [15:8]
0x44
0x4C
CHx_SCAL_GAINL
System Calibration Gain Coefficient Data [7:0]
0x45
0x4D
Reserved
-
CH0
CH1
CH2
CH3
0x33
0x3B
0x43
0x34
0x3C
0x35
0x3D
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Table 24. CHx_SCAL_SCALING
CH0-CH3 SYSTEM CALIBRATION SCALING COEFFICIENT REGISTERS
ADDR
CH0
CH1
CH2
CH3
0x36
0x3E
0x46
0x4E
NAME
DESCRIPTION
CHx_SCAL_SCALING
System Calibration Scaling Coefficient Data [5:0]
Table 25. CHx_SCAL_BITS_SELECTOR
CH0-CH3 SYSTEM CALIBRATION BIT SELECTOR REGISTERS
ADDR
CH0
CH1
CH2
CH3
0x37
0x3F
0x47
0x4F
NAME
DESCRIPTION
CHx_SCAL_BITS_SELECTOR
System Calibration Bit Selection Data [2:0]
9.6.5 Sensor Diagnostic Registers
Table 26. SENDIAG_THLD
SENSOR DIAGNOSTIC THRESHOLD (ADDRESS 0x14)
ADDRESS
0x14
NAME
REGISTER DESCRIPTION
SENDIAG_THLD
Sensor Diagnostic threshold
Table 27. SENDIAG_FLAGS
SENSOR DIAGNOSTIC FLAGS (ADDRESS 0x19)
BIT
BIT SYMBOL
BIT DESCRIPTION
7
SHORT_THLD_ FLAG
Short Circuit Threshold Flag = 1 when the absolute value of VOUT is within the absolute threshold
voltage set by the SENDIAG_THLD register.
6
RAILS_FLAG
Rails Flag = 1 when at least one of the inputs is near rail (VA or GND).
5
POR_AFT_LST_RD
Power-on-reset after last read = 1 when there was a power-on-reset event since the last time the
SENDIAG_FLAGS register was read.
Overflow flags
0x0: Normal operation
0x1: The modulator was not over-ranged, but ADC_DOUT got clamped to 0x7f_ffff (positive
fullscale) or 0x80_0000 (negative full scale)
[4:3] OFLO_FLAGS
0x2: The modulator was over-ranged (VIN > 1.2*VREF/GAIN)
0x3: The modulator was over-ranged (VIN < -1.2*VREF/GAIN)
[2:0] SAMPLED_CH
Channel Number – the sampled channel for ADC_DOUT and SENDIAG_FLAGS.
9.6.6 SPI Registers
Table 28. SPI_HANDSHAKECN
SPI HANDSHAKE CONTROL (ADDRESS 0x01)
BIT
BIT SYMBOL
BIT DESCRIPTION
[7:4] Reserved
SDO/DRDYB Driver – sets who is driving the SDO/DRDYB pin
[3:1] SDO_DRDYB_ DRIVER
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Whenever CSB is
Asserted and the Device
is Reading ADC_DOUT
Whenever CSB is
Asserted and the Device
is Not Reading
ADC_DOUT
CSB is Deasserted
0x0 (default)
SDO is driving
DRDYB is driving
High-Z
0x3
SDO is driving
DRDYB is driving
DRDYB is driving
0x4
SDO is driving
High-Z
High-Z
Others
Forbidden
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Table 28. SPI_HANDSHAKECN (continued)
SPI HANDSHAKE CONTROL (ADDRESS 0x01)
BIT
BIT SYMBOL
BIT DESCRIPTION
Switch-off trigger - refers to the switching of the output drive from the slave to the master.
0
SW_OFF_TRG
0 (default): SDO will be high-Z after the last (16th, 24th, 32nd, etc) rising edge of SCLK. This
option allows time for the slave to transfer control back to the master at the end of the frame.
1: SDO’s high-Z is postponed to the subsequent falling edge following the last (16th, 24th, 32nd,
etc) rising edge of SCLK. This option provides additional hold time for the last bit, DB0, in nonstreaming read transfers.
Table 29. SPI_STREAMCN
SPI STREAMING CONTROL (ADDRESS 0x03)
BIT
BIT SYMBOL
7
STRM_TYPE
BIT DESCRIPTION
Stream type
0 (default): Normal Streaming mode
1: Controlled Streaming mode
[6:0] STRM_ RANGE
Stream Range – selects Range for Controlled Streaming mode
Default: 0x00
Table 30. DATA_ONLY_1
DATA ONLY READ CONTROL 1 (ADDRESS 0x09)
BIT
BIT SYMBOL
BIT DESCRIPTION
7
Reserved
-
[6:0]
DATA_ONLY_ADR
Start address for the Data Only Read Transaction
Default: 0x1A
Please refer to the description of DT_ONLY_SZ in Table 31 register.
Table 31. DATA_ONLY_2
DATA ONLY READ CONTROL 2 (ADDRESS 0x0A)
BIT
[7:3]
BIT SYMBOL
BIT DESCRIPTION
Reserved
-
DATA_ONLY_SZ
Number of bytes to be read out in Data Only mode. A value of 0x0 means read one byte and 0x7
means read 8 bytes.
[2:0]
Default: 0x2
Table 32. SPI_DRDYBCN
SPI DATA READY BAR CONTROL (ADDRESS 0x11)
BIT
BIT SYMBOL
BIT DESCRIPTION
Enable DRDYB on D6
7
SPI_DRDYB_D6
0 (default): D6 is a GPIO
1: D6 = DRDYB signal
6
Reserved
5
CRC_RST
CRC Reset
0 (default): Enable CRC reset on DRDYB deassertion
1: Disable CRC reset on DRDYB deassertion
4
Reserved
Gain background calibration
3
FGA_BGCAL
0 (default): Correct FGA gain error. This is useful only if the device is operating in BgcalMode2
and ScanMode2 or ScanMode3.
1: Correct FGA gain error using the last known coefficients.
[2:0] Reserved
Default - 0x3 (do not change this value)
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Table 33. SPI_CRC_CN
CRC CONTROL (ADDRESS 0x13)
BIT
BIT SYMBOL
BIT DESCRIPTION
[7:5] Reserved
Enable CRC
4
EN_CRC
0 (default): Disable CRC
1: Enable CRC
3
Reserved
2
DRDYB_AFT_CRC
Default - 0x0 (do not change this value)
DRDYB After CRC
0 (default): DRDYB is deasserted (active high) after ADC_DOUTL is read.
1: DRDYB is deasserted after SPI_CRC_DAT (which follows ADC_DOUTL), is read.
[1:0] Reserved
-
Table 34. SPI_CRC_DAT
CRC DATA (ADDRESS 0x1D)
BIT
BIT SYMBOL
BIT DESCRIPTION
CRC Data
When written, this register reset CRC:
[7:0] CRC_DAT
Any Value: Reset CRC
When read, this register indicates the CRC data.
9.6.7 GPIO Registers
Table 35. GPIO_DIRCN
GPIO DIRECTION (ADDRESS 0x0E)
BIT
7
BIT SYMBOL
BIT DESCRIPTION
Reserved
GPIO direction control – these bits are used to control the direction of each General Purpose
Input/Outputs (GPIO) pins D0 - D6.
0 (default): Dx is an Input
x
GPIO_DIRCNx
1: Dx is an Output
where 0 ≤ x ≤ 6
For example, writing a 1 to bit 6 means D6 is an Output. (1)
(1)
If D6 is used for DRDYB, then it cannot be used for GPIO.
Table 36. GPIO_DAT
GPIO DATA (ADDRESS 0x0F)
BIT
7
BIT SYMBOL
BIT DESCRIPTION
Reserved
Write Only - when GPIO_DIRCNx = 0
0: Dx is LO
1: Dx is HI
Read Only - when GPIO_DIRCNx = 1
0: Dx driven LO
x
1: Dx driven HI
Dx
where 0 ≤ x ≤ 6
For example, writing a 0 to bit 4 means D4 is LO.
It is okay to Read the GPIOs that are configured as outputs and write to GPIOs that are configured
as inputs. Reading the GPIOs that are outputs would return the current value on those GPIOs, and
writing to the GPIOs that are inputs are neglected.
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10 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
10.1 Application Information
10.1.1 Connecting the Supplies
10.1.1.1
VA and VIO
Any ADC architecture is sensitive to spikes on the analog voltage, VA, digital input/output voltage, VIO, and
ground pins. These spikes may originate from switching power supplies, digital logic, high power devices, and
other sources. To diminish these spikes, the LMP900xx’s VA and VIO pins should be clean and well bypassed. A
0.1 µF ceramic bypass capacitor and a 1 µF tantalum capacitor should be used to bypass the LMP900xx
supplies, with the 0.1 µF capacitor placed as close to the LMP900xx as possible.
Since the LMP900xx has both external VA and VIO pins, the user has two options on how to connect these pins.
The first option is to tie VA and VIO together and power them with the same power supply. This is the most cost
effective way of powering the LMP900xx but is also the least ideal because noise from VIO can couple into VA
and negatively affect performance. The second option involves powering VA and VIO with separate power
supplies. These supply voltages can have the same amplitude or they can be different.
10.1.1.2 VREF
Operation with VREF below VA is also possible with slightly diminished performance. As VREF is reduced, the
range of acceptable analog input voltages is also reduced. Reducing the value of VREF also reduces the size of
the LSB. When the LSB size goes below the noise floor of the LMP900xx, the noise will span an increasing
number of codes and performance will degrade. For optimal performance, VREF should be the same as VA and
sourced with a clean source that is bypassed with a ceramic capacitor value of 0.1 µF and a tantalum capacitor
of 10 µF.
LMP900xx also allows ratiometric connection for noise immunity reasons. A ratiometric connection is when the
ADC’s VREFP and VREFN are used to excite the input device’s (i.e. a bridge sensor) voltage references. This type
of connection severely attenuates any VREF ripple seen the ADC output, and is thus strongly recommended.
10.1.2 Quick Start
This section shows step-by-step instructions to configure the LMP900xx to perform a simple DC reading from
CH0.
1. Apply VA = VIO = VREFP1 = 5V, and ground VREFN1
2. Apply VINP = ¾VREF and VINN = ¼VREF for CH0. Thus, set CH0 = VIN = VINP - VINN = ½VREF (CH0_INPUTCN
register)
3. Set gain = 1 (CH0_CONFIG: GAIN_SEL = 0x0)
4. Exclude the buffer from the signal path (CH0_CONFIG: BUF_EN = 0)
5. Set the background to BgcalMode2 (BGCALCN = 0x2)
6. Select VREF1 (CH0_INPUTCN: VREF_SEL = 0)
7. To use the internal CLK, set CLK_EXT_DET = 1 and CLK_SEL = 0.
8. Follow the register read/write protocol (Figure 55) to capture ADC_DOUT from CH0.
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Application Information (continued)
10.1.3 ADC_DOUT Calculation
The output code of the LMP900xx can be calculated as:
§ (VINP - VINN)
ADC_DOUT = ± ¨
©
x GAIN ·
15
¸ x (2 )
¹
VREFP - VREFN
Output Code
(13)
ADC_DOUT is in 16−bit two's complement binary format. The largest positive value is 0x7FFF (or 32767 in
decimal), while the largest negative value is 0x8000 (or 32768 in decimal). In case of an over range the value is
automatically clamped to one of these two values.
Figure 71 shows the theoretical output code, ADC_DOUT, vs. analog input voltage, VIN, using the equation
above.
ADC_DOUT
0x7FFF or 32767d
-1 LSB
|
|
(-VREF + 1LSB)
1d
|
|
+1LSB
0xFFFF or -65535d
VIN
(VREF - 1LSB)
|
|
0x8000 or -32768d
Figure 71. ADC_DOUT vs. VIN of a 16-Bit Resolution (VREF = 5.5 V, Gain = 1).
10.2 Typical Applications
10.2.1 Typical Sensor Application
2 -Wire RTD
3-Wire RTD
IB1
VIO
SCLK
IB2
CSB
1
+
VREFP1 VREFN1
VA
4-Wire RTD
Thermocouple
VA
2
3
4
VIN0
...
VIN2
...
VIN4
...
VIN6/VREFP2
VIN7/
VREFN2
GND
SDO/DRDYB
LMP90080
LM90xxx 16-bit Sensor AFE Family of Products
MicroController
SDI
D0
...
D6/DRDYB
CLK/XIN XOUT
LEDs/
Switches
Product
Channel Configuration
Current Sources
LMP90080
4 Differential/7 Single-Ended
Yes
LMP90079
4 Differential/7 Single-Ended
No
LMP90078
2 Differential/4 Single-Ended
Yes
LMP90077
2 Differential/4 Single-Ended
No
Figure 72. Typical Sensor Application
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Typical Applications (continued)
10.2.1.1 Design Requirements
• VA = 3 V
• VIO = 3 V
• 3-Wire RTD using 2 current sources
10.2.1.2 Detailed Design Procedure
Figure 72 shows the first topology for a 3-wire resistive temperature detector (RTD) application. Topology #1
uses two excitation current sources, IB1 and IB2, to create a differential voltage across VIN0 and VIN1. As a
result of using both IB1 and IB2, only one channel (VIN0-VIN1) needs to be measured. As shown in Equation 14,
the equation for this channel is IB1 x (RTD – RCOMP) assuming that RLINE1 = RLINE2.
VIN0 = IB1 (RLINE1 + RTD) + (IB1 + IB2) (RLINE3 + RREF)
VIN1 = IB2 (RLINE2 + RCOMP) + (IB1 + IB2) (RLINE3 + RREF)
If RLINE1 = RLINE2, then:
VIN = (VIN0 - VIN1) = IB1 (RTD - RCOMP)
VIN Equation for Topology #1
(14)
The PT-100 changes linearly from 100 Ω at 0°C to 146.07 Ω at 120°C. If desired, choose a suitable
compensating resistor (RCOMP) so that VIN can be virtually 0 V at any desirable temperature. For example, if
RCOMP = 100 Ω, then at 0°C, VIN = 0 V and thus a higher gain can be used.
The advantage of this circuit is its ratiometric configuration, where VREF = (IB1 + IB2) x (RREF). Equation 15
shows that a ratiometric configuration eliminates IB1 and IB2 from the output equation, thus increasing the
overall performance.
ADC_DOUT =
VIN (Gain) ( n)
2
2 VREF
ADC_DOUT =
[IB1( RTD - RCOMP) Gain] n
(2 )
2( IB1 + IB 2 ) RREF
ADC_DOUT =
>(RTD - RCOMP) Gain@
2 (2 ) RREF
( 2 n)
ADC_DOUT Showing IB1 & IB2 Elimination
(15)
Resistance ( )
10.2.1.3 Application Curve
RTD
(Temp)
Temperature (°C)
Figure 73. PT-100 RTD Resistance from –200°C to 850°C
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Typical Applications (continued)
10.2.2 3–Wire RTD
+
1 PF
3V
3V
VA
VIO
+
0.1 PF
0.1 PF
1 PF
SCLK
IB1
CSB
IB1 =
1 mA
SDO
SDI
drdyb = D6
VIN0
LMP90080
RLINE1
RTD
PT-100
RCOMP
= 0:
D5
RLINE2
Microcontroller
IB2 =
1 mA
VIN1
IB2
12 pF
VIN6/VREFP2
RLINE3
3.57
MHz
XOUT
RREF
VIN7/VREFN2
XIN/CLK
12 pF
Figure 74. Topology #1: 3-Wire RTD using 2 Current Sources
3V
3V
VA
VIO
+
+
0.1 PF
2.2 PF
0.1 PF
1 PF
SCLK
IB1
IB1 =
1 mA
CSB
SDO/DRDYB
RLINE1
SDI
VIN0
Microcontroller
RTD
PT-100
LMP90080
D2
VIN1
RLINE2
VIN6/VREFP2
RLINE3
RREF
OSC
XIN/CLK
VIN7/VREFN2
51:
Figure 75. Topology #2: 3-Wire RTD using 1 Current Source
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Typical Applications (continued)
10.2.2.1 Design Requirements
•
•
•
VA = 3V
VIO = 3V
3-Wire RTD using 1 current source
10.2.2.2 Detailed Design Procedure
Figure 75 shows the second topology for a 3-Wire RTD application. Topology #2 shows the same connection as
topology #1, but without IB2. Although this topology eliminates a current source, it requires two channel
measurements as shown in Equation 16.
VIN0 = IB1 (RLINE1 + RTD + RLINE3 + RREF)
VIN1 = IB1 (RLINE3 + RREF)
VIN6 = IB1 (RREF)
CH0 = VIN0 - VIN1 = IB1 (RLINE1 + RTD)
CH1 = VIN1 - VIN6 = IB1 (RLINE3)
Assume RLINE1 = RLINE3, thus:
CH0 - CH1 = IB1 (RTD)
VIN Equation for Topology #2
(16)
Resistance ( )
10.2.2.3 Application Curve
RTD
(Temp)
Temperature (°C)
Figure 76. PT-100 RTD Resistance from –200°C to 850°C
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Typical Applications (continued)
10.2.3 Thermocouple and IC Analog Temperature
5V
2.7V
+
+
0.1 PF
1 PF
VA
Thermocouple
VIO
Tcold
SCLK
VIN4
Thot
10 nF
VREFP1
CSB
+
TC [ VIN4 ± VIN3]
-
2.2 PF
1 PF
0.1 PF
SDO
2k
SDI
VIN3
2k
D6 = DRDYB
10 nF
LMP90080
Microcontroller
5V
LM94022
IC Temp
Sensor
+
1 PF
Tcold
VIN5
+
LM [ VIN5]
-
0.1 PF
VIN7
XOUT
5V
VREFP1
LM4140-4.1
+
1 PF
0.1 PF
0.1 PF
XIN/CLK
GND
Figure 77. Thermocouple with CJC
10.2.3.1 Design Requirements
•
•
•
VA = 5V
VIO = 2.7V
Thermocouple with Cold Junction Compensation
10.2.3.2 Detailed Design Procedure
The LMP900xx is also ideal for thermocouple temperature applications. Thermocouples have several advantages
that make them popular in many industrial and medical applications. Compare to RTDs, thermistors, and IC
sensors, thermocouples are the most rugged, least expensive, and can operate over the largest temperature
range.
A thermocouple is a sensor whose junction generates a differential voltage, VIN, that is relative to the
temperature difference (Thot – Tcold). Thot is also known as the measuring junction or “hot” junction, which is
placed at the measured environment. Tcold is also known as the reference or “cold” junction, which is placed at
the measuring system environment.
Because a thermocouple can only measure a temperature difference, it does not have the ability to measure
absolute temperature. To determine the absolute temperature of the measured environment (Thot), a technique
known as cold junction compensation (CJC) must be used.
In a CJC technique, the “cold” junction temperature, Tcold, is sensed by using an IC temperature sensor, such as
the LM94022. The temperature sensor should be placed within close proximity of the reference junction and
should have an isothermal connection to the board to minimize any potential temperature gradients.
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Typical Applications (continued)
Once Tcold is obtained, use a standard thermocouple look-up-table to find its equivalent voltage. Next, measure
the differential thermocouple voltage and add the equivalent cold junction voltage. Lastly, convert the resulting
voltage to temperature using a standard thermocouple look-up-table.
For example, assume Tcold = 20°C. The equivalent voltage from a type K thermocouple look-up-table is 0.798
mV. Next, add the measured differential thermocouple voltage to the Tcold equivalent voltage. For example, if the
thermocouple voltage is 4.096 mV, the total would be 0.798 mV + 4.096 mV = 4.894 mV. Referring to the type K
thermocouple table gives a temperature of 119.37°C for 4.894 mV.
10.2.3.3 Application Curve
Figure 78. Thermocouple Output as Function of Temperature
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11 Power Supply Recommendations
The device can be placed in Active, Power-Down, or Stand-By state.
In Power-Down, the ADC is not converting data, contents of the registers are unaffected, and there is a drastic
power reduction. In Stand-By, the ADC is not converting data, but the power is only slightly reduced so that the
device can quickly transition into the active state if desired.
These states can be selected using the PWRCN register. When written, PWRCN brings the device into the
Active, Power-Down, or Stand-By state. When read, PWRCN indicates the state of the device.
The read value would confirm the write value after a small latency (approximately 15 µs with the internal CLK). It
may be appropriate to wait for this latency to confirm the state change. Requests not adhering to this latency
requirement may be rejected.
It is not possible to make a direct transition from the power-down state to the stand-by state. This state diagram
is shown below.
PWRCN
= 11b
PWRCN
= 00b
Stand-by
PWRCN
= 01b
Active
PWRCN
= 00b
Power-down
Figure 79. Active, Power-Down, Stand-By State Diagram
12 Layout
12.1 Layout Guidelines
•
•
•
•
•
Follow the guidelines in the Power Supply Recommendations section.
Keep analog traces away from digital traces.
Never run an analog and digital trace parallel to each other.
If a digital and analog trace need to cross each other cross them at a 90° angle.
Use a solid ground plane under the device.
12.2 Layout Example
Figure 80. LMP90xx Sample Layout
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13 Device and Documentation Support
13.1 Device Support
13.1.1 Device Nomenclature
COMMON MODE REJECTION RATIO is a measure of how well in-phase signals common to both input pins are
rejected. To calculate CMRR, the change in output offset is measured while the common mode input voltage is
changed.
CMRR = 20 LOG(ΔCommon Input / ΔOutput Offset)
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) – says that the converter is equivalent to a
perfect ADC of this (ENOB) number of bits. LMP90080’s ENOB is a DC ENOB spec, not the dynamic ENOB that
is measured using FFT and SINAD. Its equation is as follows:
§ 2 x VREF/Gain·
ENOB = log2 ¨¨
¸¸
© RMS Noise ¹
(17)
GAIN ERROR is the deviation from the ideal slope of the transfer function.
INTEGRAL NON-LINEARITY (INL) is a measure of the deviation of each individual code from a straight line
through the input to output transfer function. The deviation of any given code from this straight line is measured
from the center of that code value. The end point fit method is used. INL for this product is specified over a
limited range, per the Electrical Tables.
NEGATIVE FULL-SCALE ERROR is the difference between the differential input voltage at which the output
code transitions to negative full scale and (-VREF + 1LSB).
NEGATIVE GAIN ERROR is the difference between the negative full-scale error and the offset error divided by
(VREF / Gain).
NOISE FREE RESOLUTION is a method of specifying the number of bits for a converter with noise.
§ 2 x VREF/Gain ·
NFR = log2 ¨¨
¸¸
© Peak-to-Peak Noise¹
(18)
ODR Output Data Rate.
OFFSET ERROR is the difference between the differential input voltage at which the output code transitions from
code 0000h to 0001h and 1 LSB.
POSITIVE FULL-SCALE ERROR is the difference between the differential input voltage at which the output
code transitions to positive full scale and (VREF – 1LSB).
POSITIVE GAIN ERROR is the difference between the positive full-scale error and the offset error divided by
(VREF / Gain).
POWER SUPPLY REJECTION RATIO (PSRR) is a measure of how well a change in the analog supply voltage
is rejected. PSRR is calculated from the ratio of the change in offset error for a given change in supply voltage,
expressed in dB.
PSRR = 20 LOG (ΔVA / ΔOutput Offset)
Copyright © 2011–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LMP90077 LMP90078 LMP90079 LMP90080
61
LMP90077, LMP90078, LMP90079, LMP90080
SNAS521H – JULY 2011 – REVISED JANUARY 2016
www.ti.com
13.2 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 37. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
LMP90077
Click here
Click here
Click here
Click here
Click here
LMP90078
Click here
Click here
Click here
Click here
Click here
LMP90079
Click here
Click here
Click here
Click here
Click here
LMP90080
Click here
Click here
Click here
Click here
Click here
13.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
13.4 Trademarks
E2E is a trademark of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
13.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
13.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
14 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
62
Submit Documentation Feedback
Copyright © 2011–2016, Texas Instruments Incorporated
Product Folder Links: LMP90077 LMP90078 LMP90079 LMP90080
PACKAGE OPTION ADDENDUM
www.ti.com
3-Sep-2014
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LMP90077MH/NOPB
ACTIVE
HTSSOP
PWP
28
48
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90077
MH
LMP90077MHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90077
MH
LMP90077MHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90077
MH
LMP90078MH/NOPB
ACTIVE
HTSSOP
PWP
28
48
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90078
MH
LMP90078MHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90078
MH
LMP90078MHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90078
MH
LMP90079MH/NOPB
ACTIVE
HTSSOP
PWP
28
48
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90079
MH
LMP90079MHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90079
MH
LMP90079MHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90079
MH
LMP90080MH/NOPB
ACTIVE
HTSSOP
PWP
28
48
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90080
MH
LMP90080MHE/NOPB
ACTIVE
HTSSOP
PWP
28
250
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90080
MH
LMP90080MHX/NOPB
ACTIVE
HTSSOP
PWP
28
2500
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
LMP90080
MH
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
3-Sep-2014
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF LMP90080 :
• Automotive: LMP90080-Q1
NOTE: Qualified Version Definitions:
• Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
31-May-2019
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
LMP90077MHE/NOPB
HTSSOP
PWP
28
250
178.0
16.4
LMP90077MHX/NOPB
HTSSOP
PWP
28
2500
330.0
LMP90078MHE/NOPB
HTSSOP
PWP
28
250
178.0
LMP90078MHX/NOPB
HTSSOP
PWP
28
2500
LMP90079MHE/NOPB
HTSSOP
PWP
28
LMP90079MHX/NOPB
HTSSOP
PWP
LMP90080MHE/NOPB
HTSSOP
PWP
LMP90080MHX/NOPB
HTSSOP
PWP
6.8
10.2
1.6
8.0
16.0
Q1
16.4
6.8
10.2
1.6
8.0
16.0
Q1
16.4
6.8
10.2
1.6
8.0
16.0
Q1
330.0
16.4
6.8
10.2
1.6
8.0
16.0
Q1
250
178.0
16.4
6.8
10.2
1.6
8.0
16.0
Q1
28
2500
330.0
16.4
6.8
10.2
1.6
8.0
16.0
Q1
28
250
178.0
16.4
6.8
10.2
1.6
8.0
16.0
Q1
28
2500
330.0
16.4
6.8
10.2
1.6
8.0
16.0
Q1
Pack Materials-Page 1
W
Pin1
(mm) Quadrant
PACKAGE MATERIALS INFORMATION
www.ti.com
31-May-2019
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMP90077MHE/NOPB
HTSSOP
PWP
LMP90077MHX/NOPB
HTSSOP
PWP
28
250
210.0
185.0
35.0
28
2500
367.0
367.0
38.0
LMP90078MHE/NOPB
HTSSOP
PWP
LMP90078MHX/NOPB
HTSSOP
PWP
28
250
210.0
185.0
35.0
28
2500
367.0
367.0
LMP90079MHE/NOPB
HTSSOP
38.0
PWP
28
250
210.0
185.0
35.0
LMP90079MHX/NOPB
LMP90080MHE/NOPB
HTSSOP
PWP
28
2500
367.0
367.0
38.0
HTSSOP
PWP
28
250
210.0
185.0
LMP90080MHX/NOPB
35.0
HTSSOP
PWP
28
2500
367.0
367.0
38.0
Pack Materials-Page 2
PACKAGE OUTLINE
PWP0028A
PowerPAD TM - 1.1 mm max height
SCALE 1.800
PLASTIC SMALL OUTLINE
C
6.6
TYP
6.2
A
SEATING PLANE
PIN 1 ID
AREA
28
1
9.8
9.6
NOTE 3
0.1 C
26X 0.65
2X
8.45
14
B
15
4.5
4.3
NOTE 4
0.30
0.19
0.1
C A
28X
1.1 MAX
B
0.20
TYP
0.09
SEE DETAIL A
3.15
2.75
0.25
GAGE PLANE
5.65
5.25
THERMAL
PAD
0 -8
0.10
0.02
0.7
0.5
(1)
DETAIL A
TYPICAL
4214870/A 10/2014
PowerPAD is a trademark of Texas Instruments.
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.15 mm, per side.
4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm, per side.
5. Reference JEDEC registration MO-153, variation AET.
www.ti.com
EXAMPLE BOARD LAYOUT
PWP0028A
PowerPAD TM - 1.1 mm max height
PLASTIC SMALL OUTLINE
(3.4)
NOTE 9
(3)
SOLDER
MASK
OPENING
28X (1.5)
28X (0.45)
SOLDER MASK
DEFINED PAD
1
28X (0.45)
28X (1.3)
28
26X
(0.65)
SYMM
(5.5)
(9.7)
SOLDER
MASK
OPENING
(1.3) TYP
14
15
( 0.2) TYP
VIA
(1.3)
SEE DETAILS
SYMM
(0.9) TYP
METAL COVERED
BY SOLDER MASK
(0.65) TYP
(5.8)
(6.1)
HV / ISOLATION OPTION
0.9 CLEARANCE CREEPAGE
OTHER DIMENSIONS IDENTICAL TO IPC-7351
IPC-7351 NOMINAL
0.65 CLEARANCE CREEPAGE
LAND PATTERN EXAMPLE
SCALE:6X
SOLDER MASK
OPENING
METAL
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
0.05 MAX
ALL AROUND
0.05 MIN
ALL AROUND
SOLDER MASK
DEFINED
NON SOLDER MASK
DEFINED
SOLDER MASK DETAILS
4214870/A 10/2014
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
8. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
numbers SLMA002 (www.ti.com/lit/slma002) and SLMA004 (www.ti.com/lit/slma004).
9. Size of metal pad may vary due to creepage requirement.
www.ti.com
EXAMPLE STENCIL DESIGN
PWP0028A
PowerPAD TM - 1.1 mm max height
PLASTIC SMALL OUTLINE
(3)
BASED ON
0.127 THICK
STENCIL
28X (1.5)
28X (0.45)
METAL COVERED
BY SOLDER MASK
1
28X (1.3)
28
26X (0.65)
28X (0.45)
(5.5)
BASED ON
0.127 THICK
STENCIL
SYMM
14
15
SEE TABLE FOR
DIFFERENT OPENINGS
FOR OTHER STENCIL
THICKNESSES
SYMM
(5.8)
(6.1)
HV / ISOLATION OPTION
0.9 CLEARANCE CREEPAGE
OTHER DIMENSIONS IDENTICAL TO IPC-7351
IPC-7351 NOMINAL
0.65 CLEARANCE CREEPAGE
SOLDER PASTE EXAMPLE
EXPOSED PAD
100% PRINTED SOLDER COVERAGE AREA
SCALE:6X
STENCIL
THICKNESS
SOLDER STENCIL
OPENING
0.1
0.127
0.152
0.178
3.55 X 6.37
3.0 X 5.5 (SHOWN)
2.88 X 5.16
2.66 X 4.77
4214870/A 10/2014
NOTES: (continued)
10. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
11. Board assembly site may have different recommendations for stencil design.
www.ti.com
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TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD
PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable
standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you
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TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on
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warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2019, Texas Instruments Incorporated
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