Diode across boost inductor of PFC circuit

Thread Starter

dakeeper

Joined Jan 4, 2014
4
Hey all,

I'm having trouble figuring out what D9 does here (the diode across the boost inductors + boost diodes):
http://www.ti.com/lit/df/slur515/slur515.pdf

It seems pretty ubiquitous in PFC/boost design, but I can't for the life of me find out why its there. If I had to guess, I'd say protection against transients and helping charge the output capacitors during startup. Am I right, or is there another reason? They always seem to be low leakage diodes.

Thanks
 

LesJones

Joined Jan 8, 2017
2,638
It is not directly across the inductor. D9, D30 and D24 can all supply power to J11 The one that has the most positive votage at any point in time on it's anode will supply power to J11. (You could think about it as a sort of OR gate.)

Les.
 

Thread Starter

dakeeper

Joined Jan 4, 2014
4
It is not directly across the inductor. D9, D30 and D24 can all supply power to J11 The one that has the most positive votage at any point in time on it's anode will supply power to J11. (You could think about it as a sort of OR gate.)

Les.
Alright. Thanks
 
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