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ADS8638: How to read +/-12V and 0-10V ?

Vetea Paul
Prodigy 20 points
Part Number: ADS8638
Other Parts Discussed in Thread: REF54

Tool/software:

Hello,

I am using the ADS8638 with an external reference of 3V in order to read +/-12V, everything is working fine. But now I need to be able to read +/-12V or 0 to 10V, with my external reference when I select 0-10V range I actually have 0-12V. Is there a software solution to read +/-12v or 0-10V ? I saw in the datasheet that I can't activate the internal reference (to read 0-10V) if I have an external one already connected.

Thank you for your help

  • +1
    TI__Guru**** 181021 points

    Hi Vetea,

    Are you opposed to using two references - one at 2.5 and another at 3.0?  The REF54 series of devices have an enable pin, so you could potentially swap one for the other through software via GPIO pins.  There is nothing wrong with using a 3.0V reference for 0-10V input to the ADS8638, you would just not hit the 0xFFF code.  Your 10V input would top out around code 3413 (0xD55 hex).

  • 0 in reply to Tom Hendrick
    Prodigy 20 points

    Hi Tom,


    Thank you for your quick answer, your proposition is what I am thinking about to do, but I wanted to be sure there isn't an other method just by using ADS8638 registers, in order to not complexify my design.

    So i will do what you proposed.

    Thank you