Hi Experts,
Regarding the UCC28950 with say 750W and Vout = 36V or above. In this case, the ringing of Leakage L with the synchronous FET capacitance will potentially result in overvvoltage of the Synchronous FET.
As such an active snubber is needed to clamp the drain voltage of the synch fet to a safe level.
This is often done as a sepic converter which bleeds down a capacitor (~1uF) at the drain of the synch fets (but connected to the drains via a diode).
Also, the PSFB transformer in such cases is best wound non-interleaved. This way the Leakage L slows up spike currents which woudl otherwise flow into the synch fet diode via its reverse recovery....but this extra leakage L then causes the ringing which needs the said Active snubber. May i ask why the UCC28950 makes no mention of such an active snubber.
Regards,
Marvin
