ADuCM350 giving wrong excitation voltage at sensor during Amperometric Measurement example.


I am using AmperometricMeasurement example project on EVAL-ADUCM350 board with ADuCM350 4 Wire Bio Config 3 board. It have RTIA of 1000 ohms value. But when I change macro RTIA in AmperometricMeasurement .c to 1000ohm from 7500(RTIA value for older EVAL-ADUCM350 version), I am getting a -25mV offset in excitation voltage at the sensor end. But when I make macro RTIA value as 7500, I am getting correct excitation voltage at sensor is what I have given in program.

Did I need to change anything else in program inorder to use with RTIA of 1000 ohms?

  • Hi,

    I assume that RCAL is 1000Ohm as well since you're using the BIO3Z board, and you're forcing 300mV if you're using the example code. My question is what current are you measuring? If you are measuring the onboard 6.8K-Ohm + 10uF, you might be measuring a small voltage at the ADC. Try raising the excitation voltage or change the RTIA on the board.