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TPA3110D2: Question of the TPA3110's INN and INP's Discharge Time

Wayne Chen (Audio AE)
Genius 15950 points
Part Number: TPA3110D2

Hi Sirs,

Would you pls advise if it is a normal behavior to have different discharge time between INN and INP?

Power Up: First time power up. INP and INN rise at the same slew rate with less pop noise.



Power Down: INP drops slower than INN, it makes pop noise during next power up.



Thank you and Best regards,

Wayne Chen
09/15/2017

  • 0
    TI__Expert 6985 points
    Hello Wayne! Is this the EVM you are operating and at what Vcc, load and configuration are you testing under? Thanks for your support! Thanks, Jeff
  • 0 in reply to Jeff Kohnle
    TI__Genius 15950 points
    Hello Jeff, Thanks a lot. My power supply was 12V. I did not add load when checking the input signals. Does load impedance impact input bias' rise and fall time?...Wayne Chen
  • 0 in reply to Wayne Chen (Audio AE)
    TI__Mastermind 24835 points
    Hi Wayne,
    May I asked the following questions?
    Are you using single-ended input mode or differential mode? Whant is the input signal?
    Could you do another experiment please? Connect the INN and INP to GND through 1uF capacitors, then do the same measurement as the previous one. See if the issue is still there.
    Are you using TPA3110D2 EVM? If not, could you please show me your SCH? Including all of the components/device in front of the INN/INP.
    Best regards,Shawn Zheng
  • 0 in reply to Shawn Zheng
    TI__Genius 15950 points
    Hello Shawn, I captured the waveforms with a TPA3110 EVM with no input source connected, thus the input pins were connected to GND through a 1uF cap automatically....Wayne Chen
  • 0 in reply to Wayne Chen (Audio AE)
    TI__Mastermind 24835 points

    Hi Wayne,

    This is strange. If the both input(INN/INP) are connected to GND by 1uF capacitors, the behavior should be the same. Please find the picture below which is captured by scope on TPA3110D2 EVM. You can see that the waveform for INN and INP are almost the same. Could you please double-check the input circuit?

      

    Best regards,

    Shawn Zheng

  • 0 in reply to Shawn Zheng
    TI__Genius 15950 points

    Thank you for your advise, Shawn. I double checked my GND connections, got the same result as yours....Wayne Chen