Wide input DC DC converter isolated

[sac1991]

Hey guys
I want to design a DC DC isolated power supply with input range of 9-72V and output of 28V and 10A. What could be the best choice of topology. I have been looking into active clamp forward converter topology.

Is there is a possibility to make and cascaded converter with a non isolated converter then a isolated converter

I have read about isolated sepic converter. But not finding any good reference design, it is not used that much.
Your thoughts will be he helpful!

 

[treez]

unfortunately sepic is not isolated.

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What about a Full Bridge, since you need isolation.

 

[sac1991]

Full bridge may work as well, but why not active clamp forward then again.

 

[treez]

Mind you, the wide vin range gives you a wide range of duty cycles and on times.
You have to use a pretty low fsw to guarantee your lowest on_tine isn’t too low.
With ns/np = 3.89 you end up with 54A peak of primary current when vin = 72V…considering the diagonal fet pairs each switch at 100khz and your Lout is 33uH.
So you might be better considering two paralleled converters to reduce the current

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Active clamp forward wont do anything to reduce your conduction losses.