A problem about the internal Vref Of AD7667

Hello!

I am now using an AD7667  conversion chip, and I use  the internal reference voltage, the parallel model, but my output has been FF7F, through inspection , I found that the internal reference voltage on the pin of REF is about 0.3V, this means there is something wrong with the internal reference voltage. But my PD, PDREF PDBUF is low, SER/PAR set to high (that is in parallel model), using the model of IMPULSE . 

And after many inspections ,I am sure the circuit ,pin-strap,and the chip of AD7667 are all good.So what's the problem?

Thanks for your help

Parents
  • Thanks,Tyler.

    Firstly,there are only one board,and I only change the different AD7667s on a same circuit.So the first question that you said does not exist.

    Secondly,I don't think and I am sure that the REFBUFIN pin hasn't shorted to ground,because,the PCB of the board is not wrong,and the ceramic capacitor  that connected REFBUFIN pin  has been changed a new one.It doesn't work.

    So,Tyler,do you think there are other reasons for this problem.

    Thank you !

    -Liang Lihua.

Reply
  • Thanks,Tyler.

    Firstly,there are only one board,and I only change the different AD7667s on a same circuit.So the first question that you said does not exist.

    Secondly,I don't think and I am sure that the REFBUFIN pin hasn't shorted to ground,because,the PCB of the board is not wrong,and the ceramic capacitor  that connected REFBUFIN pin  has been changed a new one.It doesn't work.

    So,Tyler,do you think there are other reasons for this problem.

    Thank you !

    -Liang Lihua.

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