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ADS8685: What is the minimum voltage changes the ADC will support and convert?

Venkatesh P17
Intellectual 895 points
Part Number: ADS8685
Other Parts Discussed in Thread: ADS8902B

Hi TI team,

Can you please mention the minimum analog voltage(in mV or nV) changes is acceptable to this part? and what is the minimum voltage(in mV or nV) to start conversion(inclusive all limitations like offset, drift etc.,)? I don't need negative side. I will put this part to monitor from 0V and above only.

  • 0
    TI__Mastermind 41765 points

     Hello Venkatesh P17,

    The minimum voltage depends on your full scale input range and ADC's  resolution, there are four unipolar ranges for ADS8685 which is a single-end input 16-bit ADC, let's assume that you want to use 0~5.12V range, this means that the full scale input range is 5.12V, so one LSB will equal 5.12/2^16, it's 78uV.

    I noticed that you had another same query about ADS8902B on E2E which is same type SAR ADC, Keith from our team is supporting you, please keep similar queries into the same thread on this forum, thanks for your support.

    e2e.ti.com/.../2641250

    Best regards

    Dale

  • 0 in reply to Dale Li
    Intellectual 895 points

    Thank you Dale Li,

    So from the datasheet it is understood that the External reference voltage is  from 4.046V to 4.146V only. So we cannot go beyond this range? With this reference voltage, the factor from 1.25 to 3 will multiply for full scale? Am I correct?

    Is these are the only options for this part? or can I adjust the multiplication factor?

  • 0 in reply to Venkatesh P17
    TI__Mastermind 41765 points
    Hello Venkatesh P17,
    The External reference voltage is from 4.046V to 4.146V only, so we cannot go beyond this range? Answer: No, you can not
    With this reference voltage, the factor from 1.25 to 3 will multiply for full scale? Am I correct? Answer: Yes.

    Thanks&Regards
    Dale