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TPA2011D1: Why doesn't TPA2011D1 stop output immediately when enable pin pull-low?

justin hsieh
Prodigy 40 points
Part Number: TPA2011D1

Dear Team,

Our customer was feedback that they can hear some pop/click noise when they stop the audio streaming.

We had measure the waveform and we found TPA2011D1 didn't shutdown the output immediately when enable pin pull-low.

The waveform was attached. 

Why doesn't TPA2011D1 stop output immediately when enable pin pull-low?

 

Justin.

  • 0
    TI__Guru** 101335 points

    Hi Justin,

    Welcome to e2e.

    The expected shut-down time is ~30uS, is your observed time much higher than this?
    This is the time that bias takes to discharge and power down the output driver.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    Prodigy 40 points

    Hi Ivan,

    Yes, the shutdown time is about 30us.

    Our customer was hear speaker has some pop/click noise when they stop audio play.

    Will the shuntdown delay cause the pop/click noise when playing discontinue audio stream?

     

    Justin.

  • 0 in reply to justin hsieh
    TI__Guru** 101335 points

    Justin,

    Can you clarify: Does the noise happens when audio is stopped, even if EN pin is not pulled-low?

    You could short the device inputs to GND (before the coupling capacitors) and check if the noise is still present when EN pin is toggled. If noise is not present then it would mean there is a mismatch at the inputs causing the noise.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    Prodigy 40 points

    Hi Ivan,

    Does the noise happens when audio is stopped, even if EN pin is not pulled-low?

    => No, there are no pop/click sounds when audio playing.

    => The customer's test case is period test that play 1s music, stop 0.25s and expect they can hear gaps in the audio, but no click/pops.

     

    You could short the device inputs to GND (before the coupling capacitors) and check if the noise is still present when EN pin is toggled.

    => There are no pop/click sound when input cap short to GND.

     

    In fact, CPU can't stop audio data immediately either when audio stram stop, CPU will finlish send out all the buffer data to the codec, and AMP still have signal input during AMP shutdown delay time.

     

    I guess maybe there is the root cause of pop/click sound occurs

     

    Justin

  • 0 in reply to justin hsieh
    TI__Guru** 101335 points

    Justin,

    That could be causing the pop, if there is signal present at the input during the power down pop can occur.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators