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TAS2562: Question of output shutdown

Feeney Xiao
Expert 3540 points
Part Number: TAS2562


hi expert，

In the application of the TAS2562, when playing at high volume, the output shutdown and then resumes after 1.4s.  We grab the PVDD waveform as the picture show, at the pause moment, the PVDD achieved about 20V. It is used by class H mode, and we test that at boost-always-on mode  the problem still exists. We used PPC3 to grab the book0 page0 register, it shows "device power down" with no other prompt when the music is interrupted 

we increase the capacitance up to 47uF*2 on the PVDD can avoid the problem. The recommended capacitance in datasheet is 47uF maximum. I want to know why this value of PVDD capacitance affects high volume scenarios and whether there is a theoretical analysis. If you have ideas for debugging, please let me know。

Thanks a lot

  • 0
    TI__Guru** 110125 points

    Hi Feeney,

    What is the load you're using for the test? I assume it is low in the range of 4Ohm, correct?
    My thought is that either the speaker or filter at the output is loading the output current too much, causing the boost to briefly overdrive. By increasing the decoupling capacitance on PVDD you help stabilize the output of the boost. A few things I would suggest:

    • Double check boost inductor saturation current, make sure it is not exceeding this limit. Use a higher current rated inductor if exceeding the limit.
    • Double check boost capacitor derating, make sure the capacitance is not drooping too low for the highest boost output voltage. Consider using a higher DC derating rated capacitor.
    • If need to increase boost capacitance, you can use the PPC3 tool to calculate the proper boost coefficients:

    Best regards,
    -Ivan Salazar
    Applications Engineer