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Headphone and SUB PWM outputs on TAS5706 TAS5716

Nicholas D'Amato
Prodigy 100 points
Other Parts Discussed in Thread: TAS5706, TAS5716

On the TAS5706 and TAS5716, which supply pins (power and ground) are used internally to supply the headphone and subwoofer PWM outputs?  

The reason for this question is that we want to include countermeasures in our schematic for suppressing TDMA noise.  

 

Thanks and Best Regards,

Nick D.

  • 0
    TI__Mastermind 22965 points

    Hi Nick,

    AVDD (Pin-10) is used to supply the HP & Sub sections on TAS5706/16.

     

    Best Regards,

    Ravinder

  • 0 in reply to Ravi Singh
    TI__Guru**** 189399 points

    Hey, Nick,

    I'd like to warn you about trying to be too clever... The power pins are all loosely tied together internally, and if you don't tied them all together externally, you're just asking for trouble... 

    Now, if you just want to hang some various small pF caps off several of the pins to trap RF, fine, but anything beyond that -- please get us your schematic for review before you cut glass.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 100 points

    Hi Don,

     

    Thanks for the head's up.  No funny business here; mostly just pF caps.  All 3.3V rails are tied together by (at most) ferrite beads.  We did run a separate return path to the power supply for high-current ground, but just a contingency plan.  The grounds are tied together at the amplifier by 0ohm jumpers for now. 

    Mostly, I wanted to know which pin to use as the HP L/R PWM signals' return path connection.  We will route the HP PWM signals together with their return path signal back to the amplifier ground pin -- basically treating it like pseudo-differential signal pairs to reduce the loop area.  Combined with 10 & 33pF caps, that should [hopefully] minimize TDMA noise pick-up.  

    Thanks again.

     

    -Nick D.