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TIC12400-Q1: how to ensure the accuracy with 0mA wet current in ADC mode

Wu JW
Intellectual 2935 points
Part Number: TIC12400-Q1

Hi, Team,

Although, the wet current is set as 0mA, there still have the leakage current in the INx pin. How to ensure the voltage measurement accuracy with ADC mode? 

  • 0
    TI__Guru 74252 points

    Wu,

    Sorry for the delay and thank you very much for your patience on this. Our applications expert has been notified and will respond accordingly.

    Regards,

  • 0
    TI__Mastermind 32970 points

    Hi JW,

    I don't have any knowledge of the resistors shown in your picture because they are external to the device.  However, there are some internal resistors between the Input pin and the ADC that form a voltage divider and will contribute to some leakage.  These resistors are shown in the functional block diagram.

    The values of the resistors are in the hundreds of kohm range  and the leakage will be within +/- 110uA as documented in the datasheet.

    Because these resistors can not be removed, the customer will need to factor in a typical 240kohm total restive load to GND in parallel to their external load, with the ADC seeing about half of that resistance due to the divider where each resistor is approximately 120kohms. 

    Or factor up to 110uA of additional current due to the leakage that will set the overall accuracy.

    Regards,

    Jonathan