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TPA3255: No Output in INPBTL Mode

TI-CSC
Genius 13890 points
Part Number: TPA3255


Tool/software:

Hello E2E Experts,

Good day.

I am using the TPA3255 in PBTL mode in my application, and I noticed that out of every 100 products, about 5 units have no output.

I found that the issue comes from the heatsink. It’s quite large and introduces interference that causes the TPA3255 to trip over-current protection earlier. When I use a smaller heatsink, the issue doesn’t occur. The heatsink seems to create parasitic capacitance that makes the TPA3255 detect over-current earlier than expected.

What can I do to eliminate this when using a large heatsink?

Regards,

TICSC

  • 0
    TI__Mastermind 19480 points

    Hello,

    Interesting. Are all heatsinks mounted the same way? Do they all have a secure connection to ground? I think the only way to permanently eliminate this would be the change the orientation of the heatsink and / or layout but I am not sure this is possible. How did you conclude there was parasitic capacitance from the heatsink? Were you measuring large peaks on the class-d output?

    I also want to ask if the smaller heatsink is acceptable for your application? 

    Regards,
    Sydney Northcutt

  • 0 in reply to Sydney Northcutt
    TI__Genius 13890 points

    Hello Sydney,

    Good day.

    When I raised the heatsink by an additional 5-10 mm, that phenomenon disappeared.

    Regards,

    TICSC

  • 0 in reply to TI-CSC
    TI__Mastermind 19480 points

    Hello,

    Is that an acceptable design modification for your system? I believe a physical change + requirement is necessary to completely eliminate this problem. 

    Regards,
    Sydney Northcutt