The LMP91000 is a programmable analog front-end (AFE) for use in micro-power
electrochemical sensing applications. It provides a complete signal path solution between a sensor
and a microcontroller that generates an output voltage proportional to the cell current. The
LMP91000s programmability enables it to support multiple electrochemical sensors such as 3-lead
toxic gas sensors and 2-lead galvanic cell sensors with a single design as opposed to the multiple
discrete solutions. The LMP91000 supports gas sensitivities over a range of 0.5 nA/ppm to 9500
nA/ppm. It also allows for an easy conversion of current ranges from 5 µA to 750 µA full scale.
The LMP91000s adjustable cell bias and transimpedance amplifier (TIA) gain are
programmable through the I2C interface. The
I2C interface can also be used for sensor diagnostics. An integrated
temperature sensor can be read by the user through the VOUT pin and used to provide additional
signal correction in the µC or monitored to verify temperature conditions at the sensor.
The LMP91000 is optimized for micro-power applications and operates over a voltage range
of 2.7 to 5.25 V. The total current consumption can be less than 10 µA. Further power savings are
possible by switching off the TIA amplifier and shorting the reference electrode to the working
electrode with an internal switch.
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