• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 30 subscribers
  • Views 374 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCM5121: po-po Noise

Ivy Jin
Expert 4985 points
Part Number: PCM5121


Hi team,

My customer use PCM5121 in their project, now they meet below issue, could you help give some suggestions? Thank you!

The customer's product supports 1-to-1 output and PCM5121 as a slave, so the CLK signal is provided by the customer, and its Mute-UnMute function is valid if the product is always working.
If after playing a 48kHz sample rate music first, the PCM5121 detects that there is no CLK signal and goes into stand-by mode, then plays a 96kHz sample rate music, the AUX out will have Po-Po noise. So the customer want to add the Mute-UnMute mechanism to the mode switch to avoid output noise, but the Mute is not valid at this time.
Below is the schematic, could you please help give some comments?
Thank you.
Regards,
Ivy
PCM5121schematic.pdf
  • 0
    TI__Mastermind 31861 points

    Hi Ivy, let me  take a look at the schematic and issue and will reply to you by the end of the week.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Mastermind 31861 points

    Hi Ivy,

    From schematic review I have few suggestions: put more caps on LDO pin, also from connections of MODE2 and MODE1 , pin 10 is VCOM, which needs do be connected to GND via a decoupling cap ( Datasheet:  VCOM output (optional mode selected by register; default setting is VREF mode.) When in VREF mode (default), this pin ties to GND. When in VCOM mode, decoupling capacitor to GND is required.

    So while they play a signal, with fs=48, at some time the clk halts and thus parts go to standby mode ,  then at this time they change to  fs=96k and they hear a pop. Can you clarify that clk is running and part is out of standby ? I am not able to see the complete steps and procedure. Can you please elaborate the sequence in more details?

    Thanks,

    Arash

  • 0 in reply to Arash Loloee
    TI__Expert 4985 points

    Hi  Arash,

    Thanks a lot for your suggestions!

    1. For the number of caps and the capacity value to be added, could you please help to give some suggestions?

    2. 

    =》PCM5121 I2S  slave mode

    1. Play 48Khz signal， I2S fs=48Khz, PCM5121 running status;
    2. Stop playing 48Khz signal, I2S clock stop, PCM5121 standby mode;
    3. Play 96khz signal, I2S fs=96Khz，PCM5121 form standby mode to running mode, And then there's “pop noise”.

    Thanks!

    Regards,

    Ivy

  • 0 in reply to Ivy Jin
    TI__Mastermind 31861 points

    Hello Ivy,

    for various cap sizes they can refer to User's Guide SLAU444A, if there is no info for a cap put a 2.2uF for decupling.

    Did you ask them to correct VCOM connection  and see if it makes any difference?

    Regards,

    Arash