UCC28910: Is there a COTS flyback transformer with 2 output for UCC28910?

Sam,

Since the output power on the 3V3 rail is so small (0.66 W), I think it may not make sense to design for a two-output Flyback transformer, mainly because it would be hard to get a suitable turns ratio for the secondaries, and it would be hard to get good regulation on the 3V3 rail as the load varies on the 5-V rail. Cross-reg with multi-output flyback is always tricky.

It might be better and certainly easier to design for a single 5-V output, and use an LDO to generate 3V3 from the 5-V rail. LDO dissipation would be ~0.34 W, is this too much for your system?

There is an existing TI design PMP4367 that delivers 5 V @ 1.2 A, which is enough to cover your power requirement, all you need to do is add an LDO on the 5-V rai lto get the second 3V3 output. This design uses a transformer designed and supplied by Wurth 750841012, which is on their website, so it should be available to buy:
www.we-online.com/.../searchpage.php


Alternatively, there is a 7.5-W design PMP9045 with a different transformer style, this was supplied by Elytone in Taiwan, transformer part number is YT29295. I can't find this on their website, but if you contact them, they should be able to get you the datasheet for this transformer, or supply you with something similar for your application.

I hope this helps answer your question, if so please click the "verify answer" button.

Thanks,
Bernard