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I am looking to add an isolated 10-12V supply capable of producing ~200mA to an existing circuit which has 5V and 12V rails available on the board. I would prefer to use the latter (12V) as it can withstand more loading, if that is possible.

I believe what I need is a DC/DC isolated converter, and after some research I think my choices are either a flyback topology, or a push-pull topology, given the power output requirements.

I already have at hand some ferrite cores (E cores and some toroids), so I will probably buy some enamel wire and wind the inductor/transformer myself. That being said, the topology doesn't seem to make a difference, component-wise; i don't mind winding more turns or adding an extra diode and transistor.

Can you suggest a specific approach? Maybe you prefer one over the other? Or maybe one of them is easier to implement?

P.S. Why is it that information about push-pull converters is so scarce? (at least compared to flyback ones)

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I'd go for flyback. It only needs one power transistor to make it work. I'd also take a look at Linear Technology's site to get an idea of chips that can help out.

Regards availability of information, flyback circuits cover the power range up to about 60 watts approximately and this is the vast majority of the market for isolated modules.

Push pull is usually used above this power up to a few hundred watts. Above this power are resonant converters and H-bridge transformer drivers.

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  • \$\begingroup\$ From my understanding push-pull designs are used for high(er) power output than flyback ones, just like you say. I suppose that either one can be scaled down and would be good enough for the <5W range that I am interested in. I already have some salvaged TL494's to use but thank you for the suggestion anyway! \$\endgroup\$ – John Lemon Mar 6 '15 at 18:24

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