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PCM5102A: Abnormal noise

Hui Cao22
Expert 1105 points
Part Number: PCM5102A

Tool/software:

When the PA switch of the power amplifier is switched, due to the discontinuous signal, the speaker emits a brief "beep" sound.

This abnormal sound will occur when switching between MUTE and UNMUTE.

There is another abnormal sound situation: first, disconnect the four signals MCLK, SCLK, FSYNC, and SDATA (power remains on, the above four signals remain at a high level, MUTE starts), and then reconnect these four signals (power remains on, the above four signals start synchronously, UNMUTE). During this operation, abnormal sounds will occur.

All hardware power supplies, signal timing sequences and signal voltages are normal.

How can this kind of noise be solved？thanks

  • 0
    TI__Intellectual 2695 points

    Hello,

    Our DAC expert is out of office for the next few days, please be patient in expecting a response.

    Best,

    Garret

  • 0
    TI__Mastermind 30711 points

    Hi,  few points regarding the schematics:

    1- It is better to use dedicated decoupling caps for each supply. So I would separate the digital and analog supplies and put dedicated caps for each at the pin to be more effective.

    2- The caps for charge pump are 2.2uF in our own EVM and DS schematics.

    3- You need to have a LPF (R &C) and then if you want, you can have AC coupling as you have it now.

    When there is a planned power down, the soft mute has to be activated to prevent the pop noise as described in datasheet. For power up , once  VDD > 2.8 V, the power-on reset function is enabled and after the initialization period, the PCM510xA is set to its default reset state. Analog output will begin ramping after valid data has been passing through the device .

    When there is  clock error  or they are stopped , the PCM510xA devices switch to an internal oscillator, and continue to the drive the output, while attenuating the data from the last known value. Once this process is complete, the PCM510xA outputs are hard muted to ground. So once the clocks are stopped, the DAC starts to muting itself.  so please make sure if there is any issue related to the DAC, it is monitored at the output of the DAC.

    So please do the above modifications and follow the procedure for PU and PD and monitor the DAC output and if there is an issue at the output of the DAC, let me know and I will help to debug.

    Regards,

    Arash