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ADS8691: Inquiry on whether there is an ADC that automatically adjusts the range within the IC

Grady Lee
Genius 4355 points
Part Number: ADS8691
Other Parts Discussed in Thread: PGA849, PGA280, OPA3S328

Tool/software:

Hi, TI expert.

The customer is currently using ADS8691 for OLED Tester board.

The customer asked if there is an ADC with the following functions.

- Normally, when measuring current, in order to increase the accuracy of the measured value, the range is adjusted and measured. (That is, the range is currently adjusted manually.)

- Is there an ADC that automatically adjusts the range within the ADC when fixing to a single power source and measuring current? (That is, an ADC that automatically adjusts the range within the ADC)

If there is an ADC that automatically adjusts the range within the ADC, can you recommend it?

Please check. Thank you.

  • +1
    TI__Guru**** 182021 points

    Hi Grady,

    Sounds like a novel idea, but unfortunately we do not have any self adjusting 'input range' ADCs in our portfolio.  I have seen customers use a MUX to change the value of their shunt resistor which provides some level of range adjustment.  Its not an automatic function, but that at least provides context back to the software regarding the LSB size of the conversion result.  As noted in Table 7-4, depending on the input range the LSB size varies from 93.75uV @ +/-12Vin to 19.53uV@ 0-5 (or +/-2.5) Vin.  I'm not sure what would need to happen in order to let the host controller understand what the LSB size is if the ADS8691 would automatically set the range.

  • +1
    TI__Intellectual 1880 points

    Hi Grady,

    What input ranges do you need? Could we discuss it via email in detail?

    For automatic gain control, we could use external programmable gain amplifiers or amplifiers with multiplexers, and comparators to automatically switch gains.

    Some options for programmable amplifier are:

    PGA280, PGA849

    You can use below amplifier as a variable gain block too. This op anmp has integrated multiplexers.

    OPA3S328

    Thanks,

    Shaury

  • 0 in reply to Shaury Anand
    Genius 4355 points

    Hi Shaury

    Thanks for reply.

    I will respond to your inquiry once it has been confirmed with the customer.

    Thanks