1 Features

1• Typical Values, TA = 25°C

• Supply Voltage 2.7 V to 5.25 V

• Supply Current (Average Over Time) <10 μA

• Cell Conditioning Current Up to 10 mA

• Reference Electrode Bias Current (85°C) 900pA

(max)

• Output Drive Current 750 μA

• Complete Potentiostat Circuit-to-Interface to Most

Chemical Cells

• Programmable Cell Bias Voltage

• Low-Bias Voltage Drift

• Programmable TIA gain 2.75 kΩ to 350 kΩ

• Sink and Source Capability

• I2C Compatible Digital Interface

• Ambient Operating Temperature –40°C to 85°C

• Package 14-Pin WSON

• Supported by WEBENCH® Sensor AFE Designer

2 Applications

• Chemical Species Identification

• Amperometric Applications

• Electrochemical Blood Glucose Meter

3 Description

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 LMP91000’s 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 LMP91000’s 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.