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PCM1803A Input Pullup

Bruce S
Prodigy 20 points

Other Parts Discussed in Thread: PCM1803A

It appears that the PCM1803A analog input has an internal pullup resistance to the reference voltage. This was observed in a circuit having a resistor in series with the input which caused a low voltage before the series resistor to increase to a higher voltage at the ADC input. Is this indeed how the ADC is wired internally? If so, how much does the internal resistance vary with temperature and from device to device?

  • 0
    TI__Guru**** 189401 points

    Hi, Bruce,

    Welcome to e2e, and thanks for your interest in our products.

    The PCM1803A indeed has internal biasing to make is easier to use in audio applications. Since this parameter is not critical in audio applications (generally), we never characterized this. I'm not sure about the tempco, but the part to part variation could be as good as +/20%.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 20 points

    Hi Don,

    Thank you for the answer. I will do some temperature testing to see how it responds in our circuit.

    Best wishes,

    Bruce