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TPA3131D2EVM: TPA3131D2EVM noise issue @ 1KHz

Hugo Wang
Expert 1525 points
Part Number: TPA3131D2EVM
Other Parts Discussed in Thread: TPA3131D2

Hi Sirs

I have a question about TPA3131D2EVM.

The input waveform as below. The noise looks is jumper wire from main board cause it.

The output waveform as below. Do you have any comments to Improve the distortion issue?

Thank you for your great support.

  • 0
    TI__Mastermind 25845 points
    Hi Hugo,

    Shawn can help you out with this question and should be posting to follow up. You may want to consider some filtering on your input to reduce the noise. I am not sure if this is the cause of the distortion at the output, however.

    Regards,

    Alex
  • 0
    TI__Mastermind 24835 points
    Hi Hugo,
    As Alex pointed, the input signal looks very noisy. For better analysis, is it possible to use a clean sinewave as the input signal?
    From the scope screen capture, the input signal amplitude is quite high, Vp=5V. This is not expected. The output will be clipped even 20dB gain setting is used. Please use a lower amplitude input signal.
    From your description, you are using a TPA3131D2 EVM, right? How much is PVCC? Load? Gain setting? And for the output filter, ferrite beads or inductors are used?
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Expert 1525 points
    Hi Shawn
    Thanks for your reply quickly. I have clarify the issue, the toot cause is GND not common ground.

    I have another question about PLIMIT.
    What is different point at output waveform when we modify PLIMIT value?

    Thank you for your great support.
  • 0 in reply to Hugo Wang
    TI__Mastermind 24835 points

    Hi Hugo,

    The PLIMIT circuit sets a limit on the output peak-to-peak voltage. The limiting is done by limiting the duty cycle to a fixed maximum value. This limit can be thought of as a "virtual" voltage rail which is lower than the supply connected to PVCC. This "virtual" rail is approximately 4 times the voltage at the PLIMIT pin. This output voltage can be used to calculate the maximum output power for a given maximum input voltage and speaker impedance.

         Best regards,

    Shawn Zheng