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PCM2900C: Noise in the Speaker when muted on Windows

Eduardo Alves da Silva
Prodigy 170 points
Part Number: PCM2900C

Hello there,

I'm using a PCM2900C, and whenever I play some audio on Windows with the speaker on mute, I hear a small noise signal on the Speaker. It only happens when there's audio playing on the computer, so I don't believe the issue is with the audio amplifier. 

Any thoughts on how to minimize this noise?

Any help is greatly appreciated.

Best Regards,

Eduardo

  • 0
    TI__Expert 5645 points

    Eduardo,

    Sorry to hear you are experiencing noise issues in your system. I have not come across something like this but I do agree w your analysis about audio amp being the contributor for the same.

    Let me look into this some more and will try to get back to you on possible ideas to minimize the noise.

    Best regards,
    Ravi

  • 0 in reply to Ravi Patil
    Prodigy 170 points
    Thank you for your help Ravi,

    If you happen to know some recommendations for board layout when using PCM2900C, it could help as well.

    It seems to me that this noise might be caused by interference from the digital part of the circuit interfering with the analog part. Does that make sense?

    Thank you,
    Eduardo
  • 0
    Prodigy 170 points
    After a long time trying out different solutions, I've finally discovered the issue, and it was a layout problem.

    D+ and D- lines went below the capacitors that were used in the preamplifier filter. This was causing the whole noise problem. A new layout was made, and it didn't show the 1kHz tone that was appearing before.