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Original question:

TLV320DAC3120: output short circuit detection - register P1R32 does not update bit 0

TLV320DAC3120: Reliable speaker short detection

Alan Ball
Prodigy 110 points
Part Number: TLV320DAC3120

Hello,

As part of a system selftest, I'm trying to reliably test that the speaker isn't shorted.

I'm trying to detect a shock in 2 ways:

  • After I turn on the class D power stage (P1R32), I wait 500 ms and then read back P1R32 to see if D7 is set.
  • I also read P0R44 an check the state of D7.

On some boards this works but on others it doesn't. How can I make my test more reliable?

As a 2nd part of my selftest a beep is emitted and I use the ADC on my microcontroller to detect a step change in the current. This works ok when no speaker / a speaker is present. However when I remove the speaker and replace it with a short there is also a step change in the current. Why is this the case?

Thanks in advance for your help with this.

Regards,

Alan

  • +1
    TI__Guru** 105305 points

    Hi Alan,

    I would suggest to also play a beep during the 1st test. The short circuit protection is based on current level, thus if the device is not actually playing the current level is very low, which may cause the protection not to trigger even if the load is shorted.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 110 points

    Hi Ivan,

    Thank you for your help. This seems to have worked on 1 of my problematic boards. I will try ang get this tested on more boards next week.

    Regards,

    Alan