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TAS2505 power down

John Hulst40
Prodigy 240 points
Other Parts Discussed in Thread: TAS2505

Hello,

I am using the TAS2505 amplifier with the Speaker Driver outputs SPKP and SPKM.

For EMC reasons, if there is no audio playing, I would like the block wave (class D) running on the SPK output to stop.

To do this I set the following register: Page1/Reg45 "Speaker amplifier control 1"  to 0x00 (D1==0)

And before playing I restart it by setting this register  to 0x02 (D1==1 )

This stops the Class D output, but the audio loudness is changing all the time for short sounds.

Maybe this is because the first data is not played while the amplifier is not started. (Adding delays did not fix the problem)

Maybe this is because I need to initialize the amplifier because of a the power down.

I also tried the Page1/Reg48 "Speaker Amplifier Volume control 2" set to 0 (SPK driver muted) , but this does not change the behaviour at the output of the SPK. There is still a block wave.

In the data sheet there is not indication on how to use this feature. Can you clarify this part of the TAS2505?

Thanks and regards.

John

  • 0
    TI__Guru** 100835 points
    Hi John,

    The way to stop the Class D output waveform is by shutting down the amplifier, through Page1/Regsiter 45.
    Where is the audio loudness changing?
    It would be better to reset and rewrite the registers into the device when it is back to operation.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 240 points

    Hi Ivan,

    Thank you for your quick reply.

    Before each sound play the audio driver is powered up with Page1/Register45. After each sound the audio driver is powered down with Page1/Register45.

    The audio loudness is changing when playing a sequence of short sounds that are repeated very quickly (depending user interaction). This includes the audio driver power up /down for every sound play. But I suppose that not the complete audio is played because the power-up is not instantaneous.

    What registers are affected by this amplifier power down, and that need to be re-initialized? This would be a lot of rewriting over I2C before playing one sound if I do the complete re-initialization.

    Best regards,

    John

  • 0 in reply to John Hulst40
    TI__Guru** 100835 points
    Hi John,

    Do you have any captures that you can share?
    I've tested tunrning on and off the speaker driver with audio streaming but I'm not able to perceive a loudness variation.
    Could you also share your register settings so we can take a look at them?

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 240 points

    Hi Ivan,

    The sounds I am playing are to indicate a key press. It is a short tick sounds .

    I suppose that I am loosing a part of the audio because the hardware is not ready after power on. (duration of sound is around 100ms) 

    The problem is only audible when playing this sound at repetition.

    I will try to work around by switching the amplifier off after a timeout of a few seconds.

    For the moment I do nto have any capture on this.

    Best regards,

    John