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UCC24610 Ton pin for SR FET question

Other Parts Discussed in Thread: UCC24610

I have question related to ucc24610 SR controller.

Question description
when I program the minimum on time with a resistor from TON to GND, occur ring and program minimun on timein direct proportion until detect Vth(off) and shut off gate for MOSFET, but action abnormal behavior.

How to explain this phenomenon and suppress this ring? thanks.

As below FIG.

Blue trace is Vd of MOSFET

Purple trace is gate of MOSFET

  • Kuo,

    Can you give more details, sch, component values?

    If the SR gate on-time seems to be about 1.5 us, then I assume that the resistor on the TON pin is approx. 100 k?

    The ringing may be due to the PCB layout parasitic inductance, and maybe even the SR MOSFET package that is used. It might be possible to improve it by adding small value resistors in series with both VD and VS pins, but they should be the same value and ideally small value. This is explained on page 18 of the UCC24610 datasheet, with eqn. 1 to help calculate the required resistor value.

    I hope this helps.

    Thanks,
    Bernard