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TPA3110D2: undershoot of input signal

takishin
Expert 2360 points
Part Number: TPA3110D2

Our customer has a question about TPA3110D2.
I'm posting the question for the customer:

++++++++++++++++++++++++++++++++++++++++++++++

We have measured an input voltage wave of RINN pin on our evaluation board of TPA3110D2.
The input signal has an undershoot which is -0.4V although the Absolute Maximum Rating value is -0.3Vmin.

If the board is working in this situation, is it possible to cause any damage to the device?

We'd like to use this just as it is.

++++++++++++++++++++++++++++++++++++++++++++++

Thank you in advance.

Best regards,
Takishin

  • 0
    TI__Expert 6985 points
    Hello Takishin! Shawn can answer any further questions that you may have, but in general absolute Min & Max values do have some margin, but are set because each application configuration can be different and so we have to set these values carefully. For example length of time, ambient temperature, etc can cause a lot of stress variability that we cannot comprehend in our specs. This is why we state: "Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability." Thanks, Jeff
  • 0
    TI__Mastermind 24835 points

    Hi Shinji-san,

    This is actually a problem about reliability.  A permanent damage is probably caused by stresses beyond the Absolute Maximum Ratings. Exposure to absolute-maximum-rated condition for extended period may affect device reliability.

    May I know how the undershoot is caused? Is it possible that power up the audio amplifer after the undershoot on input? Or anything can be done to suppress the undershoot before going to the input of audio amplifer?

    Best regards,

    Shawn ZHeng 

     

  • 0 in reply to Shawn Zheng
    Expert 2360 points
    Hello Jeff-san and Shawn-san,

    Thank you for your answers.


    >May I know how the undershoot is caused?

    It is power-on noise from audio output.

    >Is it possible that power up the audio amplifier after the undershoot on input?

    I have a question.

    Can the negative voltage beyond -0.3V be applied to the input pins when the amplifier is Off-State?

    Best regards,
    Takishin
  • 0 in reply to takishin
    TI__Mastermind 24835 points

    Hi Takishin-san,

    I think there should be a step from High to Low on the input signal before the input capacitors, which cause the minus undershoot. There is a probablity that the -0.4V undershoot could cause latch-up in the input, which is dangerous.

    One resolution is to find the root cause of the undershoot and make the input signal within the recommendation range. The other way is to power up the audio amplitude after the overshoot. (SD doesn't work for the solution) 

    Best regards,

    Shawn Zheng

  • 0 in reply to Shawn Zheng
    Expert 2360 points
    Hello Shawn-san,

    Thank you for your prompt reply.
    I understand.

    Best regards,
    Takishin