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TPA6211A1-Q1: POP noise at entering shutdown mode

Akio Ito
Genius 3595 points
Part Number: TPA6211A1-Q1
Other Parts Discussed in Thread: TPA6203A1, TPA6211A1

Hi,

We received inquiries from a customer about the POP noise of TPA6211A1-Q1 entering shutdown mode.
The lower Figures are the circuitry of their designed board and observed waveforms of it.

channel 1 : /SHUTDOWN
channel 2 : SPOUT-
channel 3 : SPOUT+
function 2 : (SPOUT+) - (SPOUT-)

Q1: Is the level of POP noise (function 2 waveform) at the falling edge of /SHUTDOWN signal as same as EVM?
Q2: Is there any way to reduce the POP noise?

Best regards,

Akio Ito

  • 0
    TI__Mastermind 20085 points

    Hi Ito-san,

    Q1) The pop noise level depends on the system's design.
    Q2) First of all, I can't watch in the schematic what kind of input you are using. The pop noise is produced by an unbalanced input if you are using a single-ended input It is recommended to change it to a differential input.
    Second of all, If the system is using a differential input, the issue could be caused because there is insufficient time in the shutdown to discharge the input capacitor, so you could reduce the input capacitor in order to reduce the discharge time of the capacitors and avoid the pop noise. Another option could be to leave of sending input signal a little before of setting the shutdown mode.
    Finally, you could refer the next application report: SLOA124 to find a possible solution to your problem. This application report was done for the TPA6203A1, but this device is very similar to the TPA6211A1 that is the commercial version of the TPA6211A1-Q. This solution could work in the TPA6211A1-Q1.

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer

  • 0 in reply to José Luis
    Genius 3595 points

    José-san,

    Thank you for the answer.
    The input signal is not single-ended but full differential signal from DSP. But I will recommend him trying 'Additional Discharge Paths for Bias Voltage' of SLOA124.

    Best regards,

    Akio Ito