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TAS5717 Headphone noise

masanobicchi
Prodigy 30 points
Other Parts Discussed in Thread: TAS5717

I made a original board with TAS5717.

Headphones always have white noise whatever I2S data is all 0.

Speakers don't have noise.

Output waves of Headphones have spike noise about 500kHz period.

When the signal bypass Internal OPAMP , Noise is cleared.

Power supply is from LDO(TPS76333DBV). Maybe no problem.

Please teach me the way to erase headphone noise using Internal OPAMP.

  • 0
    TI__Guru 57800 points

    Hello Masanobicchi, 

    Welcome to E2E, thanks for your interest in our products!

    I suppose that you are configuring the headphone driver to receive the PWM signal generated in the device (I2S audio). If that is the case, you should follow the  software setup instructions indicated in page 56 of the Datasheet. Do you have the proper filtering for the application?,  we recommend to follow our EVM schematic and layout, also I would suggest to take a look to the  Using the TAS5717/9 as a 2nd order filter section of the Datasheet.

    Could you please explain what do you mean with "bypass Internal OPAMP", are you refering to the headphone/line driver?

    Thanks and Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 30 points

    Hello Diego-san,

    >I suppose that you are configuring the headphone driver to receive the PWM signal generated in the device (I2S audio). If that is the case, you should follow the  software setup instructions indicated in page 56 of the Datasheet. Do you have the proper filtering for the application?

    I think I can set right register. I set as below.

    Address Data

    0x00 74
    0x04 05
    0x05 13
    0x07 00 c0 
    0x1b 80
    0x20 00 01 77 72

    >  we recommend to follow our EVM schematic and layout, also I would suggest to take a look to the  Using the TAS5717/9 as a 2nd order filter section of the Datasheet.

    And Filter is same as the EVM. I copied the schematics from User's Guide(SLOU303).

    But my layout is a little different from your design, because copying layout is difficult.

    > "bypass Internal OPAMP"

    In fact, I shorted between -(HPL_IN) and output(HPL_OUT) of OPAMP(Internal OPAMP of TAS5717).

    The gain of headphone is low, but I can't hear noise.

    Thank you.

  • 0 in reply to masanobicchi
    Prodigy 30 points

    I captured waveform.

    HP_PWM

    After 1st (C + R)Lowpass filter.

    HPL_OUT

    HPL_OUT with cursor

    I think pulses are the source of the noise. From where does it come???