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TPA3116D2: Causes and solutions for impact noise from amplifier when power-off

Cherry Zhou
Mastermind 22235 points
Part Number: TPA3116D2
Other Parts Discussed in Thread: NE5532

The customer intends to use the TPA3116D2 as an amplifier, and would like to know the following info:

1. What is the specific reason for the impact sound when the amplifier chip is in use when turned on and off?

2. Is there an effective solution on the hardware?

3. Class-D amplifiers sometimes have NE5532 added to the front stage, and does this have any effect?

Thanks a lot!

Best Regards,

Cherry Zhou

  • 0
    TI__Mastermind 19030 points

    Hi Cherry,

    Q1, do you mean pop noise when power up/off? The pop noise is mainly related to mismatch of audio input and output.

    Q2, I can not fully understand. what the effective solution on the hardware means?

    Q3, No. that is fine.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    TI__Mastermind 22235 points

    Hi Derek,

    Thanks for your reply!

    Yanming Gong said:
    pop noise when power up/off?

    Yes. And the customer wonders what causes this noise to occur, is it caused by the shock currents at the power supply during the power up and power down moments? Or, is it because the entire chip is unevenly powered during power-up and power-down that causes the DC point at the output to change?

    Yanming Gong said:
    what the effective solution on the hardware means?

     The customer would like to know how to solve this problem with the peripheral hardware circuitry, and how to control the silent feet of the amplifier chip?

    Thanks!

    Best Regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Mastermind 19030 points

    Hi Cherry,

    The pop noise is from the mis-match of OUTP_N. 

    –Input mismatch

    –DC offset.

    –Inductor/layout mismatch

    I suggest the power sequence:

    1. Amp is disabled
    2. Initialize DAC.
    3. Enable Amp (SDZ high).
    4. Mute AMP.   
    5. Begin audio out from DAC.
    6. Un-mute AMP.

    1. When Enable Amp (SDZ High)-------- Mute Amplifier first, Then SDZ High, Delay >40ms then Unmute Amplifier.
    2. Add a delay (>20ms) to ‘Finish Initialize DAC’ and ‘Enable Amp (SDZ high)’.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    TI__Mastermind 22235 points

    Hi Derek,

    Thanks for your reply!

    And the customer still has a question:

    Why do the outputs mismatch, the DC level offset, and so on at the power up and power down moments, and therefore resulting in a short burst sound. Is this caused by uneven power on the chip for a short time?

    Thanks and expecting the updates!

    Best Regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Mastermind 22235 points

    Hi Derek,

    May I know is there any updates about the latest questions?

    Thanks a lot!

    Best Regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Mastermind 19030 points

    Hi Cherry,

    Yes. The main reason is the audio input DC caps mismatch. So the suggestion above is for this. Waiting device power up successfully, then unmute output.

    Regards,

    Derek