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TPA3255: TPA3255 Short circuit protection

Darren Yang
Expert 2000 points
Part Number: TPA3255
Other Parts Discussed in Thread: TPA3251

Hi, our customer use TPA3255 meet same Short circuit protection issue, if the TPA3255 output short circuit it will be burn TPA3255 Immediately ，however，the input without any voice at this period；from the datasheet we can see the TPA3255 has Short circuit protection funtions，but it donot describe clearly how the Short circuit protection work ，could you give same comment and give some sugestions how to avoid burn TPA3255 when happn short circuit？

  • 0
    TI__Mastermind 24835 points
    Hi Darren,
    Could you please help to show the SCH for this application? It helps our debug work.
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Expert 2000 points

    Hi Shawn
    the SCH is designed under the datasheet ，if not happen short circuit，it will be work well，now we need you help check the short circuit protect how to work beacuse the datasheet describle not clealy how its work and pls help check the SCH give some suggestions，tks！

  • 0 in reply to Darren Yang
    Expert 2000 points
    Hi Shawn
    could you help to check it and short circuit protect deeply description，tks！
  • 0 in reply to Darren Yang
    TI__Mastermind 27920 points
    Hi Darren,

    Are you saying the device is getting physically damaged from a short? What type of short is occurring, pin to pin (OUT A to OUT B), pin to ground, or pin to supply?

    The schematic shows that 10 uH inductors are being used, can you confirm that they are 10 uH and that the saturation current is above the max current expected during use? I bring this up because the OC circuitry in the TPA32551 has a minimum inductance of 5 uH in order to operate correctly in all scenarios. If the inductors are saturating and dropping below 5 uH then this could be the issue.

    Can you explain more about the testing conditions?
    -Load used
    -Input signal
    -power output
    -PVDD

    Justin
  • 0 in reply to Justin Bohr
    Expert 2000 points
    Hi, Justin
    sorry for delay reply you，I want to know why once happy short, it will burn the IC, could you help describe the short circuit protect specific working principle of the TPA325X , how much current and how long is the short circuit protection? Because the datasheet description is very blurry
  • 0 in reply to Darren Yang
    Expert 2000 points
    Hi Justin
    add more detal condition，OUT A to OUT B short ，10UH saturation current is 15A
  • 0 in reply to Darren Yang
    Expert 2000 points
    Hi Justin
    sorry to disturb you，because customer Urge us tightly,tks!
  • 0 in reply to Darren Yang
    TI__Mastermind 27920 points
    Hi Daren,

    If the device is in BTL mode, and there is a short from out A to out B, then the device should be able to protect itself. If you can give mo more details about the system that I requested in the post above, I may be able to help debug the problem. Additional information like the intended mode of operation, the resulting FAULT and CLIP OTW indicators after the failure. Is there damage to any of the passives? Is the device physically shorted at the pins before the inductors?

    Justin
  • 0 in reply to Justin Bohr
    Expert 2000 points
    Hi Justin
    when happen a short from out A to out B，the device is be burn rather than protect itselt，the FAULT and CLIP OTW we will provide later，is only damage to TPA3251，no happen device physically short at the before the inductors，it so Surprised to us is that this device short protect is not working at all, so we want to know how long it can last and how much current it can withstand when short circuit protection occurs, from the datasheet, the short protect describe is not clearly，tks！
    Load used：4ohms
    -power output：200W
    -PVDD:34V for TPA3251; 41V for TPA3255
  • 0 in reply to Darren Yang
    TI__Mastermind 27920 points
    Hi Darren,

    Are the devices in BTL or PBTL mode? If you have accidentally put the device in SE mode, PPSC will be disabled, and if shorted to PVDD or GND, it will damage the device. What is the resistor settings you have on your board for M1 and M2?

    The OC protection takes 150 ns to respond to an OC event. Since the device takes 150 ns to respond to an OC event, the rate at which the current increases must be slowed to ensure the 150ns delay does not result in a damaging level of current. This requirement is why we require a minimum of 5 uH of inductance.

    If it is a short event before the inductors, the device will be damaged.

    Justin