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TPA3140D2: TPA3140D2 found 10k noise issue

JeffYC Yang
Expert 1290 points
Part Number: TPA3140D2

Hi sir,

I have meet noise issue on TPA3140D2, please refer to below test waveform.

Any point need I check first?

I will provide schematic and layout later.

TPA3140 noise-1.pdf

TPA3140 noise-2.pdf

Thanks!

Jeff

  • 0
    Expert 1290 points

    Hi Sir,

    We have tried connect C19/C20 to GND or floating, this noise will disappear. Do you have any idea?

    below is schematic and layout.

    WIFI_ASR_IO_V1.pdf

    AMAZON-P1A-PCB.PDF

    Thanks!

    Jeff

  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points

    Hi Jeff,

    Thanks for asking questions in E2E. Form your test result, there is 10kHz noise on your output. In this case, there is no input signal on the amplifier, right? 

    When you float the input, the noise disappear, so I think you need to check the input signal or input circuit. For the input circuit, you can refer to our EVM design.  http://www.ti.com/lit/ug/slou405/slou405.pdf

    Best regards,

    Shawn Zheng

  • 0 in reply to Shawn Zheng
    Expert 1290 points
    Hi Shawn,

    Yes, after check the TPA3140, this noise is from input, but we already remount all of component except TPA3140 relative component, it seems the noise from itself.
    Is it possible caused by GND layout?
    could you please help to check the layout is meet TPA3140 requirement?

    thanks!
  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points

    Hi Jeff,

    Form your PCB files, looks like the AMP net are connected to CHARG_IN, is this expected? I think you need to check the input circuit to make sure the input path is clean.

  • 0 in reply to Shawn Zheng
    Expert 1290 points

    Hi Shawn,

    I think it no connect to CHARG_IN, you can refer to below figure.

    And now we tried disconnect C20, but still can measure 10kHz noise on pin12.

    And I check almost layout meet layout guide.

    Do you have any idea?

    Thanks!

    Jeff

  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points
    Hi Jeff,
    Thanks for the measurement. So, even the both input pins are float, there is a 10kHz noise shown on the input pins, right? Could you please show the waveform by the scope? Is it possible that the noise is from power supply? Did you check the GND, is the GND plant clean enough? We never saw 10kHz noise on the input pins before.

    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Expert 1290 points

    Hi Shawn,

    Yes, even the both input pins are float, there is a 10kHz noise shown on the input pin. Seems noise from 

    Please refer to below waveform. I check the GND layout was followed below layout guide...

    "The AVCC (pin 14) decoupling capacitor should be connected to ground (GND). The PVCC

    decoupling capacitors should connect to GND. Analog ground and power ground should be connected at the
    thermal pad, which should be used as a central ground connection or star ground for the TPA3140D2."

    thanks!

    Jeff

  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points
    Hi Jeff,
    I'm sorry I can see the pictures, could you please use the rich formatting?
  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points
    Hi Jeff,
    Did you measure the waveform and the frequency specturmon on GND and Power supply? Any 10kHz noise on them?
  • 0 in reply to Shawn Zheng
    Expert 1290 points
    Hi Shawn,

    Only measure power supply have no this noise. If used 12V battery, still can see this 10khz.

    Thanks!
    Jeff
  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points

    Hi Jeff,

    The noise issue is device dependent or board dependent? In another word, what if use another device on the same board?

  • 0 in reply to Shawn Zheng
    Expert 1290 points

    Hi Shawn,

    You mean change another TPA3140D2 to check the symptom?

    We have already tried 2~3pcs, but still can found this 10kkHz noise.

    Thanks!

    Jeff

  • 0 in reply to JeffYC Yang
    Expert 1290 points
    Hi Shawn,

    We have tried change SSCTRL pin to connect GND, found can solve 10kHz noise, do you have more detail about Spread Spectrum and De-Phase Control?
    Why it cause 10kHz noise?

    Thanks!
    Jeff
  • 0 in reply to JeffYC Yang
    TI__Mastermind 24835 points
    Hi Jeff,
    When spread spectrum and de-phase control are enable on TPA3140, the THD performance only decreases around 0.5dB.
    The 10kHz noise shown in your picture is very large, we think it probably comes from the power ro GND. The noise is coupled to input, then it's enlarged by the 36dB gain on the audio amplitude. You can try to use differential input mode to mitigate the noise on input. And, the GNDing is also very important for the noise mitigation, please also check the GNDing performance on your board. With good GNDing and differential input mode, the 10kHz noise should be empressed a lot.
    Best regards,
    Shawn Zheng