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TPA3131D2: waveform distortion

Shu-Cheng LIN
Guru 11785 points
Part Number: TPA3131D2


Hi Sirs,

We have use TPA3131D2. Some phenomenon as below. Is this a normal IC features? could you help us to fix and explain it? Thanks for your kindly help!!

1. When PVCC is 9V or 8V, If setting volume to 100%, the waveform will be distortion. But if PVCC is setting lower than 8 or 9V, the waveform distortion will be better.

PVCC 9V

PVCC 8V

2. When PVCC is 9V or 8V, There won't be waveform distortion (Sine wave) when volume is setting to 40%

Our schematic

3131d2.output-new.pdf

  • 0
    TI__Mastermind 24835 points
    Hi Shu-Cheng,
    How much is the input signal amplitude for 100% volume? I saw 26dB gain is used in you SCH, you could calculate the expected enlarged output signal amplitude by it. While the PLIMIT volatege is around 2.83V from your SCH. So the PLIMIT clipping threshold(around 4 times of the the voltage on PLIMIT pin) is higher than PVCC=8V or 9V. When the input signal amplitude is very high, the output is actually limited by PVCC instead of PLIMIT when PVCC=8V or 9V. Then the clipping is worse with lower power supply volatge. With decreasing the input signal amplitude, the enlarged output signal amplitude also decrease. When the output amplitude is lower than PVCC and PLIMIT threshold, the clipping disappears.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    TI__Mastermind 24835 points
    Hi Shu-Cheng,
    Could you please help to close this question if it's answered? Please let us know if you have more question.
    Best regards,
    Shawn Zheng