isolated, modulated current source from 230V/50Hz with max 25A/90V

Norman,

I would not recommend a flyback for a 25A design. The ripple current in the output capacitors will be excessive.

For this design I would recommend an active clamp forward converter using our UCC2894 or a half bridge using a UCC2808.

Regards,

Richard.

Richard,

is an applications note available for the UCC2808 how to use them behind a PFC (390V)?

Norman,

Using the UCC2808 after a PFC front end is the same as using any other controller. You are designing a DC/DC converter with input voltage of 390VDC. So your component selection will have to be such that they can handle this high voltage. Unfortunately I don't have an app note that covers this topic.

any other app note or ref-design I can learn from? Maybe from the PFCs? What PCF circuit would you recommend?

Norman

Norman,

Here you will find a lot of good papers on PSU design, http://focus.ti.com/docs/training/catalog/events/event.jhtml?sku=SEM401001

For the PFC take a look at the UCC3817/8, http://focus.ti.com/docs/prod/folders/print/ucc3818.html#applicationnotes, you will find an EVM and MathCAD file to help with component selection.

Richard.

Hello Norman,

Which solution did you take? I´ve got a simmilar problem and I´m searching for a good solution.

Karl