LMP91051 Datasheet, PDF (1/23 Pages) Texas Instruments – Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications

LMP91051
www.ti.com
SNAS581A – MARCH 2012 – REVISED NOVEMBER 2012
LMP91051 Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications
Check for Samples: LMP91051
FEATURES
1
•2 Dual Channel Input
• Programmable gain amplifier
• “Dark Signal” offset cancellation
• Supports external filtering
• Common mode generator and 8 bit DAC
• Package 14 pin TSSOP
APPLICATIONS
• NDIR sensing
• Demand control ventilation
• Building monitoring
• CO2 cabin control — Automotive
• Alcohol detection — Automotive
• Industrial safety and security
• GHG & Freons detection platforms
DESCRIPTION
The LMP91051 is a dual channel programmable integrated Sensor Analog Front End (AFE) optimized for
thermopile sensors, as typically used in NDIR applications. It provides a complete signal path solution between a
sensor and microcontroller that generates an output voltage proportional to the thermopile voltage. The
LMP91051's programmability enables it to support multiple thermopile sensors with a single design as opposed
to the multiple discrete solutions.
The LMP91051 features a programmable gain amplifier (PGA), “dark phase” offset cancellation, and an
adjustable common mode generator (1.15V or 2.59V) which increases output dynamic range. The PGA offers a
low gain range of 167V/V to 1335V/V plus a high gain range of 1002V/V to 7986V/V which enables the user to
utilize thermopiles with different sensitivities. The PGA is highlighted by low gain drift (20 ppm/°C), output offset
drift (230 μV/°C at G = 1002 V/V), phase delay drift (300 ns) and noise specifications (0.1 μV_RMS 0.1 to 10Hz) .
The offset cancellation circuitry compensates for the “dark signal” by adding an equal and opposite offset to the
input of the second stage, thus removing the original offset from the output signal. This offset cancellation
circuitry allows optimized usage of the ADC full scale and relaxes ADC resolution requirements.
The LMP91051 allows extra signal filtering (high pass, low pass or band pass) through dedicated pins A0 and
A1, in order to remove out of band noise. The user can program through the on board SPI interface. Available in
a small form factor 14 pin TSSOP package, the LMP91051 operates from -40 to +105°C.
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2012, Texas Instruments Incorporated