LMP91051

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SNAS581A – MARCH 2012 – REVISED NOVEMBER 2012

LMP91051 Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications

Check for Samples: LMP91051

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FEATURES

APPLICATIONS

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Dual Channel Input

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NDIR sensing

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Programmable gain amplifier

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Demand control ventilation

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“Dark Signal” offset cancellation

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Building monitoring

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Supports external filtering

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CO2 cabin control — Automotive

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Common mode generator and 8 bit DAC

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Alcohol detection — Automotive

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Package 14 pin TSSOP

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Industrial safety and security

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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

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.

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PRODUCTION DATA information is current as of publication date.

Copyright © 2012, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.