UCC256301: Suggestion for Vin = 42V-140V, Vout = 48V @ 5-6A isolated design

Hello Prahlad,

For LLC to operate correctly you should limit the input range to work less than 2 to 1. This converter is requiring a 3 to 1 input range so the UCC256301 would not be a good choice.

Regular forwarded converter would work for this application. However, if you want ZVS the other choice would be a phase shifted full bridge.  I was going to recommend and active clamp forwarded converter but presently those controllers can’t achieve ZVS.

I looked through TI’s reference designs and could not find any existing designs that met your input and output power requirements. There is a 300W phase shifted full bridge reference design Vin 400V to 750V, Vout = 24V/12A.  You could possibly adjust the transformer turns ratio to meet your needs. http://www.ti.com/product/UCC28950/toolssoftware

There is also a MathCad and Excel design tool you can use to figure out what the turns ratio would be. You can find it at the above link.

Please note that this is not a device I generally support. So if you have further questions repost it on the e2e with UCC28950 in the title so the appropriate support engineer can help you with your design.

Regards,

Mike