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TAS5717 Outputs tying together for a common audio output

stan knoblich
Prodigy 40 points
Other Parts Discussed in Thread: TAS5717

Hello, I would like to know on the outputs of the TAS5717 OUTA,B,C,D, is there a problem with tying the  designated minus outputs say B and C together for a common connection?  We have a situation where, like a headphone jack, the connections have Right, Left and a common. Will this cause any safety problem with the amp? Not doable? Thanks for your input.

Stan

  • 0
    TI__Mastermind 33420 points

    Hello Stan:

    For TAS5717 ouputs A, B, C and D, these are high power output and are used to drive speakers.  TAS5717 also has headphone driver and can be used to drive headphones.  The output configuration for the HP is single-ended in the TAS5717 EVM.

    http://www.ti.com/lit/ug/slou303/slou303.pdf

    Best regards,

    Tuan

  • 0 in reply to Tuan
    Prodigy 40 points

    Thanks Tuan,

    Is there a device that I can take the outputs of the TAS5717 and feed them to headphones? We do not have any analog inputs to feed the headphones in on the TAS5717.

    Thanks,

    Stan 

  • 0 in reply to stan knoblich
    TI__Mastermind 33420 points

    Hi Stan:
    TAS5717 HP has the charge pump creating -3.3V.  It will accept 1Vrms input without clipping.  Do you need to bias this at a different DC level?

    Best regards,

    Tuan

  • 0 in reply to Tuan
    Prodigy 40 points

    Hi Tuan,

    The problem is that we only have serial audio HDMI audio going to the TAS5717 so we can not use the headphone input at least that is what I understand from the data sheet. So we only have the outputs A,B,C,D. Earlier you said that we should not tie the minus sides together because of the differentials. Plus we can not tie this to a single ground as per most headphones. I have heard of 4 conductor headphones but I do not think that ever flew. So I was wondering if you knew of a device that could take the differential outputs and drive headphones but it does not sound like we can.

     Thanks,

    Stan 

  • 0 in reply to stan knoblich
    TI__Guru**** 189401 points

    Hi, Stan,

    TAS5717 can TOTALLY do what you want. Look at the d/s, page 56, Case 2. How could you miss this? :)

    Seriously, I think this will work just fine for you. You can route I2S to HP_PWM out and then wire that to the HP driver that Tuan was talking about. QED.

    The EVM is set up to allow this signal routing to be evaluated. You just need to make sure JP1, JP2, and I2C registers are properly set.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 40 points

    d2,

    Thanks! How did I miss that on page 56? :0 I think I fell asleep at page 50...

    That might actually work!

      Stan