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TPA6211A1-Q1: POP Noise during power on with SD pulled low

Paul Ren
Prodigy 640 points
Part Number: TPA6211A1-Q1
Other Parts Discussed in Thread: TPA6211A1, PCM5100

Hello,

My customer has a pop noise problem with TPA6211A1 during 5V power up. The background and tests we have done are listed as the following.  

1. Input of TPA6211A1 is single ended and IN- is coupled with PCM5100 with 1uF capacitor and IN+ is connected to ground with 1uF and 20K resistor in series.

2. /SD is alway keep low after 5V start-up.

3. when 5V power is off and turned on after a short within a few sends, we will hear the pop noise, enven the /SD is still low.

4. We do see an unballanced output during 5V power-up and unballanced input.

My questions is that: the output of TPA6211A1 should be high impedance when /SD is pulled low, why there is unballaced output, especially when Vcc exceeds 2.5V? Is there anyway to avoid the pop noise?

Below is the waveform we captured.

  • 0
    TI__Mastermind 20085 points

    Hello Paul,

    The pop noise is caused by an unbalanced input in a Single-ended input configuration, so you could use a differential input configuration to avoid this issue. If you can't change the input configuration, so you verify that the tolerance of discrete components is adequate. The resistors should have a tolerance of 1% and the capacitors of 10%.
    You can refer the next application report: Single-ended Input Reduction for TPA6203A1 to find another way to reduce pop noise. 

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer