Mosfet driver bootstrap capacitor discharge on no-load?

Status
Not open for further replies.
G

grizedale

Advanced Member level 3
Joined
Jun 13, 2011
Messages
838
Helped
17
Reputation
34
Reaction score
17
Trophy points
1,298
Activity points
8,804
Hello,


Will the bootstrap capacitor on this high and low side driver stay charged up when the full-bridge smps goes on no-load?


NCP5181
https://www.onsemi.com/pub_link/Collateral/NCP5181-D.PDF

The SMPS is:-
Full-Bridge at 84KHz,
Vin = 210VDC -373VDC
Vout = +-40V
Pout = 335W

How much dummy loading will i have to add in order to keep the bootstrap cpacitor charged up?
 

The required condition is, that the low side switch has non zero on-time. Then the bootstrap cicruit will work, independant of the load.
 
ok thanks, but no load means zero on time, so surely it cant be independent of the load.
 

no load means zero on time
Click to expand...
I don't think so. Zero on time means no output voltage. But the feedback loop still maintains the output voltage at zero load. I don't know, if the circuit operates stable at zero load, but this shouldn't be a real problem, even temporary drop of bootstrap voltage and deactiviation of the high side driver won't be necessarily. I think, it's more a question to be decided by empirical tests than prediction.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…