LMP90100 and LMP9009x Sensor AFE System: Multichannel, Low-Power, 24-Bit Sensor AFE With True Continuous Background Calibration

1 Features

• 24-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 to 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 (LMP90100/LMP90098)
• 4-DIFF / 7-SE Inputs (LMP90100/LMP90099)
• 2-DIFF / 4-SE Inputs (LMP90098/LMP90097)
• 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 21.5/19 Bits
  • Offset Error (Typical) 8.4 nV
  • Gain Error (Typical) 7 ppm
  • Total Noise < 10 µV-rms
  • Integral Nonlinearity (INL Maximum) ± 15 ppm of FSR
  • 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
  • 28-Pin HTSSOP Exposed Pad

2 Applications

• Temperature and Pressure Transmitters
• Strain Gauge Interface
• Industrial Process Control

3 Description

The LMP90xxx is a highly integrated, multichannel, low-power, 24-bit Sensor AFEs. The devices features a precision, 24-bit Sigma-Delta analog-to-digital converter (ADC) with a low-noise 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.

1. For all available packages, see the orderable addendum at the end of the datasheet.

4 Typical Application Schematic

5 Revision History

Changes from R Revision (January 2015) to S Revision

• Changed Buffer Enable/Disable. Go
• Changed BUF_EN = 1 to 0. Go

Changes from Q Revision (December 2014) to R Revision

• Added SDO Timing Requirements back in. Go

Changes from P Revision (March 2013) to Q Revision

• 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 Go
• Added footnote to INL, GE, and Crosstalk specifications.Go
• Changed t_DOD1 specification to 27nsGo
• Added sentence to the end of the Reset and Restart section.Go
• Deleted CH_STS from Compute the CRC... sentence.Go

Changes from O Revision (March 2013) to P Revision

• Changed layout of National Data Sheet to TI formatGo

6 Description (continued)

Another feature of the LMP90100/LMP90099/LMP90098/LMP90097 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 LMP90100/LMP90098 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 LMP90100/LMP90099/LMP90098/LMP90097 complete analog front-ends for low-power, precision sensor applications such as temperature, pressure, strain gauge, and industrial process control. The LMP90100/LMP90099/LMP90098/LMP90097 are ensured over the extended temperature range of
-40°C to +125°C and are available in a 28-pin HTSSOP package with an exposed pad.

7 Pin Configuration and Functions

HTSSOP (PWP0028A) PACKAGE

28 PINS

TOP VIEW

See below for specific information regarding options LMP90099, LMP90098, and LMP90097.