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PCM1862/PCM1864 with DC coupled inputs

Diego Ismirlian
Prodigy 80 points
Other Parts Discussed in Thread: PCM1864

Hello,

I'd like to use the PCM1864 (4 channel audio ADC) for our next design, but I have a question about the inputs. I want to DC-couple the inputs, because I want to extend the bandwidth to less than 1Hz in the lower end, and to avoid the >10uF coupling capacitors.

The datasheet doesn't specify the common mode voltage at the inputs. Is it at AVDD/2? Does the VREF pin give access to this bias voltage?

Thank you very much in advance.

Regards,

Diego.

  • 0
    TI__Mastermind 27850 points
    Hi Diego,

    Yes, VREF is a pin that can be used to bias the input circuit to 0.5 *AVDD. I do not have test data with the PCM186X below 1 Hz, as we do have a HPF with an Fc = 1 Hz for the main ADCs. I do not know how this will affect your application, but the secondary ADC is able to read DC values on its own.

    Justin