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TPA3116D2EVM: Amp shutdown inconsistent

Michael Swanson12
Intellectual 290 points
Part Number: TPA3116D2EVM
Other Parts Discussed in Thread: TPA3116D2

Hello

I am observing my EVM shutdown at various amplifier output voltages.  I have the PLIMIT jumper connected (J4) so PLIMIT should be approx my PVCC which is 24V. 

I was testing output capabilities with 8 & 4 Ohm Dummy Loads and a ~794mVrms input sin tones and sweeps.  This input level was max before my output was clipping.  I was able to get about 15.5Vrms output here.  I was inputting to only 1 of 2 input channels of EVM. 

Then I input to both L & R of the EVM and noticed if playing low frequency sin tones for an extended amount of time (180Hz for about 1-2minutes) the output was dropping out.  Output would be about 15Vrms and drop to 0V for ~2.5s then turn back on to about 15Vrms.  After this happened, my EVM was susceptible to shut down at output levels as low as 1-3Vrms with various frequency sin tones & pink noise.    All the above was tested in BTL mode. 

Next I set up my EVM in PBTL and noticed it was able to handle the pink noise at max output for about 1-2minutes.  Then sin tones started shutting the amp down at various output levels. 

Any ideas if this is expected per thermal/current limitations of the amp and its implementation in the EVM?  I would like to drive a 3Ohm (2x 6 Ohm in parallel) load at 11Vrms maximum. 

Thanks.  Let me know if any more info is needed

-Mike

  • 0
    TI__Mastermind 24835 points

    Hi Mike,

    For 15Vrms output voltage on 4Ohm load, the output power could reach 56W for each channel. This exceeds the TPA3116D2 output power ability and the thermal limit of the board, then OT FAULT is triggered. On the EVM board, the SDZ is connected to FAULTz pin, so the device is set to shut-down mode by this. The temperature on the device goes down because there is no output power. When the temperature is lower than the OT protection THD, the FUALT is cleared and the device goes back to the normal operation mode again.

    For your application(2*6Ohm, 11VRMS), the total output power is around 2*20W. I think there isn't any poroblem for TPA3116D2. Please use the appropriate power supply voltage to make sure there is no clip on the output. And please pay highly attention to the thermal performance during your PCB layout design. You can find some design guidelines in section 10 in the datasheet. Our EVM is also a good example.

    Best regards,

    Shawn Zheng   

  • 0 in reply to Shawn Zheng
    Intellectual 290 points
    Hi Shawn
    Thanks for the explanation.

    Curious how you came to terms that my application should not be a problem? Output = 11Vrms & Load = 3Ohm (2x 6 ohm in parallel) ...40W right?

    How does the power supply effect the maximum output? If I limit it to something lower than 24V, could I essentially set my max output to 11Vrms?

    Thanks
    -Mike
  • 0 in reply to Michael Swanson12
    TI__Mastermind 24835 points
    Hi Michael,
    TPA3116D2 can support 2*20W on 6Ohm load. Did you try this on your EVM board? Per our previous experience, it should work without any problem on the EVM. Power supply can't be too low to clip the output signal. I think 20V power supply is high enough for 11Vrms output.
    Best regards,
    Shawn Zheng