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Original question:

ADS8684: Voltage monitoring of negative supply (-6.5V)

ADS8684: ADS8684A

Alexandre Ferez
Prodigy 20 points
Part Number: ADS8684
Other Parts Discussed in Thread: ADS8694,

Is it possible to measure negative voltages in unipolar range just connecting AINxP to ground and the negative input signal to AINxGND pin? I know I can configure the input to read bipolar but doing it I will loose resolution. I need to keep 16 bit resolution measuring just negative signal (-VIN to 0 in 65536 steps). Actually I will have 3 inputs reading positive voltages and 1 input reading negative voltages and I need to keep 16-bit resolution on all of them.

  • 0
    TI__Mastermind 45685 points

    Hello Alexandre,

    The AIN_xGND pin is limited to below range, you can not do this, otherwise, the ADC may be damaged because the signal to AIN_xGND has violated the Absolute Maximum input range. ADS8694 can be used to meet your requirement which is pin-pin compatible ADC as ADS8684. Please check ADS8694 datasheet.

    Please let me know if you have more questions, thanks.

    Best regards

    Dale

  • 0 in reply to Dale Li
    Prodigy 20 points

    Sorry, I was looking at ADS8684A datasheet and there, I have not found explicit this limitation for AIN_nGND to GND. Please let me know if it can be done like I asked on the ADS8484A or if it is missing this information there.

    Regards,

    Alexandre

  • 0 in reply to Alexandre Ferez
    TI__Mastermind 45685 points

    Hi Alexandre,

    ADS8684A is same as ADS8684 only except Alarm feature and more input ranges, the information "AUX_GND to GND" in Absolute Maximum Ratings table of ADS8684A datasheet should be AIN_nGND to GND. The datasheet should be corrected, I apologized to make  you confused.

    Regards

    Dale