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TPA3132D2: Speaker detection for TPA3132D2

Caspar Chen
Prodigy 100 points
Part Number: TPA3132D2
Other Parts Discussed in Thread: TPA2005D1-Q1

Tool/software:

Hi E2E team,

Our customers require that the detection circuit be implemented in TPA3132D2 with reference to the following voltage divider design:

I would like to consult with you if this will have any side effects?
If so, do you have any suggestions for detection circuit design?

Thanks.

BR,

Caspar

  • 0
    TI__Intellectual 2335 points

    Hi Caspar,

    I would recommend that the voltage divider on the lower leg is exactly replicated on the top leg instead of having a single resistor. Having different circuits could cause some pop noise.

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 100 points

    Hi Ramsey,

    Thanks for your advice. Due to MCU is 1.8V power domain, I redesigned the voltage divider resistor values.

    Could you help me review it. If there is any doubt please correct me.

    [Note] AMP_PWR is 12V

    BR,

    Caspar

  • 0 in reply to Caspar Chen
    TI__Intellectual 2335 points

    Hi Caspar,

    I did some more analysis on your speaker monitor design and cannot recommend that this sort of circuit is used. When the device is first given power, the PWM does not begin immediately but the resistor divider will supply a DC to the speaker which could cause damage. Even if DC blocking capacitors are used, this will cause issue if the device switches in and out of Hi-Z mode. If you want to detect a speaker, the best way I can think of would be to add a current sensing resistor in series after the LC filter and snubbers but before the speaker on both the + and - speaker inputs. If a speaker is connected there will be current through the resistors which could be measured. If no speaker is connected, there is no current through the resistors and thus no voltage detected.

    Regards,

    Ramsey

  • 0 in reply to Ramsey Foote
    Prodigy 100 points

    Hi Ramsey,

    I found a discussion on a similar circuit on E2E. Its title is "TPA2005D1-Q1 Speaker open and short circuit detection".
    The circuits are somewhat similar. The main difference is that they are pulled back from the N terminal for detection. In our circuit, they are pulled back from the P terminal for detection. Do you think it is more reasonable to import the design in the article there into TPA3132D2? Or is it still recommended to use current sense.

    BR,

    Caspar

  • +1 in reply to Caspar Chen
    TI__Intellectual 2335 points

    Hi Caspar,

    This circuit will work, but the device will need to be in Hi-Z mode.

    Regards,

    Ramsey