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TPA3255: TPA3255 don't enter CB3C mode

Gary Teng
Genius 5860 points
Part Number: TPA3255

Hi Sir,

 My customer use TPA3255 in their speaker project. They want to test CB3C mode and use Roc in 30K ohm (they try 22K ohm and have the same result) but TPA3255 always work in latch mode (need reset to clear the OC issue). Is there anything we have to check for CB3C function? Thanks.

Test condition:

Vcc = 46V, Rload = 1ohm, Roc = 30K ohm

Best regards,

Gary

  • 0
    TI__Mastermind 27990 points
    Hi Gary,

    With an Roc of 30k to ground, CB3C should be functioning at 12.9A. The easiest way to verify this is to look at the PWM output of the channel hitting the limit and watch for it to skip pulses. The CB3C function for the TPA3255 will not hold the device at the current limit forever. After a number of PWM pulse skips the device will shut down. CB3C is meant to protect from over current from short transients in audio that hit the peak output.

    Justin