LMP91050

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SNAS517D – NOVEMBER 2011 – REVISED MARCH 2013

LMP91050 Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications

Check for Samples: LMP91050

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FEATURES

DESCRIPTION

The LMP91050 is a programmable integrated Sensor

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•

Programmable Gain Amplifier

Analog Front End (AFE) optimized for thermopile

•

“Dark Signal” Offset Cancellation

sensors, as typically used in NDIR applications. It

•

Supports External Filtering

provides a complete signal path solution between a

sensor and microcontroller that generates an output

•

Common Mode Generator and 8 bit DAC

voltage proportional to the thermopile voltage. The

LMP91050's programmability enables it to support

APPLICATIONS

multiple thermopile sensors with a single design as

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NDIR Sensing

opposed to the multiple discrete solutions.

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Demand Control Ventilation

The

LMP91050

features

a

programmable

gain

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Building Monitoring

amplifier (PGA), “dark phase” offset cancellation, and

an adjustable common mode generator (1.15V or

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CO2 Cabin Control — Automotive

2.59V) which increases output dynamic range. The

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Alcohol Detection — Automotive

PGA offers a low gain range of 167V/V to 1335V/V

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Industrial Safety and Security

plus a high gain range of 1002V/V to 7986V/V which

enables the user to utilize thermopiles with different

•

GHG & Freons Detection Platforms

sensitivities. The PGA is highlighted by low gain drift

(100 ppm/°C), output offset drift (1.2mV/°C at G =

KEY SPECIFICATIONS

1002 V/V), phase delay drift (500ns) and noise

•

Programmable gain 167 to 7986 V/V

specifications (0.1

cancellation circuitry compensates for the “dark

•

Low noise (0.1 to 10 Hz) 0.1

μVRMS

signal” by adding an equal and opposite offset to the

•

Gain Drift 100 ppm/°C (max)

input of the second stage, thus removing the original

•

Phase Delay Drift 500 ns (max)

offset from the output signal. This offset cancellation

circuitry allows optimized usage of the ADC full scale

•

Power supply voltage range 2.7 to 5.5 V

and relaxes ADC resolution requirements.

The LMP91050 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 10–pin package, the

LMP91050 operates from -40 to +105°C.

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PRODUCTION DATA information is current as of publication date.

Copyright © 2011–2013, 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.