lmp91200 error reduction

Discussion in 'The Projects Forum' started by Avshi, May 21, 2015.

  1. Avshi

    Thread Starter Member

    Jan 16, 2015
    Hello! I want to use lmp91200 to measure pH in a tank and arduino is not capable of detecting differential voltage(like in lmp91200 case). I want to send the analog signal to only one adc to reduce read error from arduino because without additional hardware I must read both vocm and vout on seperate adc's which I think will introduce more significant error then finding the difference with hardware. I want to make the output as a single analog signal by using INA149 in dual supply mode (using lm828 to produce negative voltage) to find difference (only requires one adc). Would this method produce less erroneous results then simply using 2 adc's?

    Attached is the proposed circuit (I am a novice, please let me know if something is incorrectly or unnecessarily implemented).

    EDIT: it has been recommended by engineers at TI that I use ADS1115, ADS1118 or ADS1120 which makes things simpler.
    Last edited: May 22, 2015