LM5160A: lm5160a

dang xiaofeng

Prodigy 200 points

Part Number: LM5160A

Tool/software:

LM5160DNTFBKEVM评估版中，为啥原副边绕组电流以及二极管VD对地，这三个值会振荡呢

over 1 year ago

0 Youhao Xi over 1 year ago

TI__Guru* 78400 points

Hi Xiaofeng,

Thank you for posting. What do you mean by "三个值会振荡呢"? Could you clarify your question?

Regards,

Youhao

0 dang xiaofeng over 1 year ago in reply to Youhao Xi

Prodigy 200 points

As shown by the three arrows in the figure:when the switch on, there is vibration.

+1 Youhao Xi over 1 year ago in reply to dang xiaofeng

TI__Guru* 78400 points

Or, those are the ringing caused by the reverse recovery of the diode on the secondary side. Placing a snubber across the diode can help.

Hope this clarifies.

Youhao

0 dang xiaofeng over 1 year ago in reply to Youhao Xi

Prodigy 200 points

I feel that the effect of leakage is more possible

0 dang xiaofeng over 1 year ago in reply to dang xiaofeng

Prodigy 200 points

another question: what't the dead time between the high-side and low-side FET?

+1 Youhao Xi over 1 year ago in reply to dang xiaofeng

TI__Guru* 78400 points

You are right that the leakage is part of the resonance of ringing.

There is no fixed dead time. Instead, it is adaptive by cross checking the high side and low side FET's switching to prevent shoot-through, always.

Hope this clarifies.

Regards,

Youhao

0 dang xiaofeng over 1 year ago in reply to Youhao Xi

Prodigy 200 points

But I don't understand why it rings ？in particular， Ipri is negative in the previous moment (or in the dead time ),then i can find the way to solve the question

0 Youhao Xi over 1 year ago in reply to dang xiaofeng

TI__Guru* 78400 points

Think of a flyback converter for that switching edge, and when the primary side FET turns on, the diode becomes reverse biased and there would be resonance between the leakage inductor resonance with the diode's junction capacitance during reverse recovery.

Hope this clarifies.

Thanks,

Youhao