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PCM2706: pop-noise

GARETH OU
Mastermind 8825 points
Part Number: PCM2706

Hi

Customer use PCM2706CPJTR as my audio design. Currently, I have a pop-noise issue and symptom as below.

 

Speaker plug in DUT R/L. 

Power on system into Windows 10 or plug in and out QB-058 from USB port.

Can hear "Bo" noise sound. 

 QB-058.pdf

  • 0
    TI__Guru* 95285 points

    Hi Gareth,

    Can you provide further details to better understand how/where is the pop happening?

    • What is DUT R/L? Is it the output of the OPA LINE_OUT_R and LINE_OUT_L?
    • Pop happens when the whole system is being powered up? I assume it is being powered by VBUS (5V), correct?
    • Can you separate the PCM DAC from OPA amp? You can remove AC coupling capacitors for this purpose. Once they're separated, repeat your tests and see with a scope if the pop is present at the output of the PCM or at the input of the OPA.
    • Most likely you'll need to add some resistors to GND between PCM output and OPA input to help with charge/discharge of the capacitors in the audio signal path. Pop is commonly caused by mismatch between the inputs of an amplifier, and it's more common in single-ended implementations.

    Best regards,
    -Ivan Salazar
    Applications Engineer