I have a customer who is experiencing the following issue with the LM5046:
I am testing prototype of ZVS full bridge with LM5046. Everything works very well with exception of maximum input voltage and minimum load, that is the condition where effective output duty cycle goes to zero (both sides of the bridge are in phase). In this condition controller "freezes" with one side stuck at high and the other stuck at low. This state persists for about 20us when transformer saturates creating massive current spike. This issue does not seem to be related to power components or layout as it occurs also with power components disconnected. Output voltage is 230V, so I am not using synchronous rectifiers, hence very low duty cycle at minimum load. How to fix it?
I have schematics and waveforms, but I cannot post them on-line. Can we take this off-line?
Thanks for your help with this!
Richard Elmquist
