Hi,

I request you to review the various design examples that we have provided on our website. Please use the link below to review:

http://www.powerint.com/en/design-support/reference-designs/design-examples

For the power level that you are interested in, you may be able to use TNY280 from the TinySwitch-III family depending on the thermal design of your product.

http://www.powerint.com/en/products/tinyswitch-family/tinyswitch-iii

If your application is a universal input sealed adapter, you should consider TOPSwitch-JX family and the parts to use will be TOP266VG, TOP265KG or TOP264EG depending on choice of heatsinking arrangement.

http://www.powerint.com/products/topswitch-family/topswitch-jx

I suggest you study the following design examples, which should help you to design the feedback circuit for your design.

http://www.powerint.com/sites/default/files/images/schematics/di12.gif

http://www.powerint.com/sites/default/files/images/schematics/di117.gif

Regards

PI-Sarek