LMP91000: AFE System for Sensors: Configuring AFE Potentials for Low-Power Chemical Sensing Applications
The LMP91000 is a programmable analog front end (AFE) in electrochemical sensing applications using micropower.
It provides a complete signal path solution between a sensor and a microcontroller that produces an output voltage proportional to battery current. The programmability of the LMP91000 enables it to support multiple electrochemical sensors, e.g. 3 lead toxic gas sensors and 2 lead galvanic sensors multiple discrete solutions rather than a single design.
LMP91000 Support Gas Sensitivity
0.5 NA/ppm to 9500 NA/ppm range. It also allows a 5µA current range from 750µA to full scale with ease.
The LMP91000's regulated cell bias and impedance amplifier (TIA) gain is programmed through the I2C interface.
The I2C interface can also be used for sensor diagnostics.
The integrated temperature sensor can be read by the user via the VOUT pin to provide additional correction in the μC signal or temperature monitoring to verify the condition of the sensor.
The LMP91000 is optimized for micropower applications and over a voltage range of 2.7V to 5.25V. The total current consumption can exceed 10µA. Further power savings to turn off the TIA's amplifier may short-circuit the working electrode to the reference electrode with an internal switch.
Features Typical, TA = 25°C
■ Power supply voltage 2.7 V to 5.25 V
■Supply current (average time) <10μA
■Cell conditioning current up to 10 mA
■ Bias current of reference electrode (85℃) 900pA (maximum)
■Output drive current 750μA
■Complete potentiometric circuit interface to most chemical cells ■Programmable cell bias voltage ■Low bias voltage drift ■Programmable gain of TIA 2.75kΩ to 350kΩ
■ Receiver and source capabilities ■ I2C compatible digital interface ■ Operating ambient temperature: -40°C to 85°C
■Package 14-pin LLP
■Supports AFE design applications through WEBENCH sensors ■Chemical species identification ■Amperometric applications ■Electrochemical blood glucose meters