Quasi-Resonant Flyback Converter Universal Off-Line Input 65-W Evaluation Module

Hello Mahdi,

Thank you for your interest in UCC28600.

The 65W EVM is an 18V @ 3.6A, in order to modify this for your spec you will have to make the following changes for starters:

1. R18 and R17 to now reflect 12Vout.
2. The output current is increased from 3.6A to 5A, you will have to increase the number of turns on the sec side. 
3. Transformers normally have an RMS current limit, in order to avoid overheating and reduced efficiency I would recommend checking this value.
4. R6 and R8 will require recalculation to reflect 12 Vout.

PMP5315 is a closer design to your spec, it would be easier to modify this unit without a transformer change because of the higher peak current.

The excel calculator tool attached is a good way to modify your application spec and check for the component values.

Regards,

Sonal