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Original question:

TLV320DAC3100: Speaker output waveform

TLV320DAC3100: Is it ok to make the device DC output when the device at silence playback ?

Matthew Chen
Intellectual 1440 points
Part Number: TLV320DAC3100


Hi team,

There is a 320kHz output signal from SPKM & SPKP when TLV320DAC3100 works. Is it ok to configure the device  outputs at a certain DC level? Customer wants to make audio lead-off detection through this way.

Do you have any suggestion for the lead-off detection?

Thanks a lot.

Matthew

  • 0
    TI__Guru** 110435 points

    Hi Matthew,

    Can you elaborate on what lead-off detection would be? Is it something like open load?
    It is not usually recommended to force DC voltages to speakers as it could cause damage.

    Regarding if it's possible to play a DC voltage, I think you may be able to do so, although I don't think it has been tested as it's not a common audio application requirement. I can test an EVM and get some results early next week.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    TI__Intellectual 1440 points

    Hi Ivan,

    Thanks for your kindly support here.

    Please share the results if you get tested.

    Matthew

  • 0 in reply to Matthew Chen
    TI__Guru** 110435 points

    Hi Matthew,

    After testing, it seems not possible to play DC signals out of the Speaker driver, it will briefly be present at the output but then be cancelled out, here is a capture for reference:

    There must be some high pass filter internal to the device to prevent damage on speakers due to DC voltages.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    TI__Intellectual 1440 points

    Hi Ivan,

    Thanks for that, according to the waveform. it seems our device supports 0v output, which is enough for the audio off detection. Could you share how to set up the device with 0V?

    Matthew

  • 0 in reply to Matthew Chen
    TI__Guru** 110435 points

    Hi Matthew,

    I used an AUX-0025 filter for this test, which is a fully reconstruction filter for Class-D amplifiers measurement. Similar results can be obtained if using LC or RC filters with cutoff frequency around 20k-30kHz.

    Best regards,
    -Ivan Salazar
    Applications Engineer