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PCM2902: There is noise in the output

user5883945
Expert 1351 points
Part Number: PCM2902
Other Parts Discussed in Thread: , PCM2900

Dears,

   We use PCM2902 for codec, have two input channel, USB for digital and analog path; there have noise in output when chose analog input path, do you have advise for this issue, thanks!

  

  • 0
    TI__Genius 17835 points

    Hello,

    Thank you for reaching out. First, please note that the PCM2902 is marked as "not recommended for new designs" (NRND), if possible, I recommend using the PCM2902C or a different USB CODEC marked with an "Active" status. 

    With regards to the noise issue, where is the noise found on the analog signal path? In general, we recommend using a low pass filter on the output. The LPF should be placed after the DC Blocking capacitors and before the connector or amplifier (shown in PCM2900 TYPICAL CIRCUIT CONNECTION 1). 

    I would also reccomend probing the input before and after the DC Block cap to see if you can find more information about the noise. What is the frequency, amplitude and source of the noise? 

    Let me know your feedback.

    Best,
    Andrew