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PCM1809: Single ended analog input output issue

Stanley Ho
Prodigy 550 points

Part Number: PCM1809
Other Parts Discussed in Thread: PCM1822

Tool/software:

Hi Expert,

A customer is using PCM1809 with single ended analog input.  They apply 1Vrms as input but I2S output only has -6dBFS instead of 0dBFS.  Can you help to review the schematic and advise what may have gone wrong?

Stanley

  • 0
    TI__Expert 8810 points

    Hi Stanley,

    The full-scale analog input for PCM1809 is defined for a fully-differential input, which is 2Vrms. Since we are giving single-ended 1Vrms to INP, the ADC still sees a signal fo 1Vrms, and hence is providing I2C output as -6dBFS.

    To get true 0dBFS signal for a 1Vrms input, recommendation would be to use a PCM1822 ADC, which is a pin and package compatible device to the PCM1809.

    For this device

    1) The full-scale input is defined for single-ended as 1Vrms

    2) The ADC supports AC-coupled inputs only.

    Thanks and Regards,

    Lakshmi Narasimhan