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Query regarding power fluctuation in UCC28610D

Hiren Thumar
Intellectual 470 points
Other Parts Discussed in Thread: UCC24610

Hello sir,

 Please find attached schematic file(PMP5952 EVM file). This schematic circuit converts  230vAC to 5v @5A DC

  • 5V power used for USB type C charging circuit, MCU card, RGB card

While testing we observed some issue like below:

1) When load is not connected ,the power fluctuation of around 800mV. But when we connect load for turning on PWM based RGB led, we observed power fluctuation of around  1.6V. so kindly suggest us How to resolve this power fluctuations in our circuit?

 Any help would be appreciated. Thanks in advance.

  • 0
    TI__Expert 4015 points

    Hi, I suspect that this is due to the light load behavior of the UCC24610. I would look at the gate drive of Q1 during these voltage excursions and observe when it is being driven and not driven.

    sPer section 7.3.2 of the datasheet, the SR controller will enter light load mode under certain conditions. The will result in the addition or removal of the SR diode drop to the output voltage and may result in the transient voltage deviations you are seeing.

    Hope this helps.

    Thanks

    Billy

  • 0 in reply to Billy Long
    Intellectual 470 points
    hi sir,
    Thanks for provide suggestion.
    we refer section 7.3.2 of the datasheet. and also testing in our design in many time UCC24610 not wake up in normal mode.

    so how to configure always work in normal mode in UCC24610??
  • 0 in reply to Hiren Thumar
    TI__Expert 4015 points
    I don't believe it's possible to always configure the device to work in normal mode, but by reducing the minimum Ton (via R11) you can reduce the load level at which it enters light load mode. You need to be careful not to reduce Ton to such a low level that the ringing on the Vs node does not spuriously turn off the gate drive.

    The easiest way to resolve this issue is to fit an inductor between C5 and C6 to filter out the unwanted ripple.

    Hope this helps.
    Thanks
    Billy