Multioutput SMPS with coupled output inductor experience?

This is the APnote I was talking about. Forgot to link it

Its the Lloyd Dixon Coupled inductor app note from the SEM500 power supply seminars.

From memory ('89-'90), a 10% auxiliary cross-regulation (+/-5%) from a fully regulated 5V output is realistic to expect from a coupled inductor forward, in an old standard PC configuration. This scales over the 125W -350W design range. Reduced minimum loading on auxiliaries and main output is as predicted - instead a total minimum system load avoids the coupling nonlinearities associated with discontinuous choke current.

Your problem is the loading imbalance (extreme if you're actually inhibiting the 150V output). You're in the power range of a flyback, which doesn't develop cross-reg through the same mechanisms, and all your current levels are low. Why a forward converter here?

RL

The input voltage can be as high a 625V and as low as 300V. I was toying with the idea of a double ended flyback but the voltage and good transformer utilization of a full bridge lead me in that direction.

I'm looking for a desing with low stress on the Mosfets and Diodes. The high current pulse of a flyback always seened to lead me away from them.

What do you think of a DE flyback for this situation?

That would address your voltage stress issue, wouldn't it? Allows lower-loss leakage recovery, as well, for peaky currents.

RL