ADC with independant GND and Vref


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  1. #1
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    Default ADC with independant GND and Vref

    Hello,

    I'm wondering if it is possible to implement an ADC knowing the analog input has no connection to the PIC's VDD & VSS.

    Is this possible?
    Roger

  2. #2
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    Default Re: ADC with independant GND and Vref

    Is doable using a galvanic isolator.

    Cheers

    Al.
    All progress began with an idea

  3. #3
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    Default Re: ADC with independant GND and Vref

    You mean something like a DC-DC converter?
    Roger

  4. #4
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    Default Re: ADC with independant GND and Vref

    No! Something like the Texas component slyt211. But there are several others doing the same job.

    Cheers

    Al.
    All progress began with an idea

  5. #5
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    Default Re: ADC with independant GND and Vref

    ...but, the SLYT211 is a (miniature) DC-DC converter or am I missing something?
    Roger

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    Default Re: ADC with independant GND and Vref

    Much simpler would be an external V/F converter that can be close to the source ( LM331 as an oldie ! ) http://www12.fairchildsemi.com/ds/KA/KA331.pdf then an opto-coupler :
    you then just have to measure the incoming frequency ...

    Alain
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  7. #7
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    Default Re: ADC with independant GND and Vref

    It is a galvanic isolator. It is also a DC-DC converter but this is just semantic. You need primarely a galvanic isolation.

    Alain suggestion to use a voltage to frequency converter, is an interesting and cheap approch!

    Cheers

    Al.
    All progress began with an idea

  8. #8
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    Default Re: ADC with independant GND and Vref

    Thanks for all the suggestions.

    I never tried a V/F.

    I'll give it a try
    Roger

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