54F175DMQB Datasheet, PDF (1/23 Pages) Texas Instruments – LMP91050 Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications

LMP91050
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SNAS517D – NOVEMBER 2011 – REVISED MARCH 2013
LMP91050 Configurable AFE for Nondispersive Infrared (NDIR) Sensing Applications
Check for Samples: LMP91050
FEATURES
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•2 Programmable Gain Amplifier
• “Dark Signal” Offset Cancellation
• Supports External Filtering
• Common Mode Generator and 8 bit DAC
APPLICATIONS
• NDIR Sensing
• Demand Control Ventilation
• Building Monitoring
• CO2 Cabin Control — Automotive
• Alcohol Detection — Automotive
• Industrial Safety and Security
• GHG & Freons Detection Platforms
KEY SPECIFICATIONS
• Programmable gain 167 to 7986 V/V
• Low noise (0.1 to 10 Hz) 0.1 μVRMS
• Gain Drift 100 ppm/°C (max)
• Phase Delay Drift 500 ns (max)
• Power supply voltage range 2.7 to 5.5 V
DESCRIPTION
The LMP91050 is a 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
LMP91050's programmability enables it to support
multiple thermopile sensors with a single design as
opposed to the multiple discrete solutions.
The LMP91050 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
(100 ppm/°C), output offset drift (1.2mV/°C at G =
1002 V/V), phase delay drift (500ns) 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 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.
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