Don't Know this part number!

i recently took apart an ATX supply and found this IC inside...i believe it probably is the controller/PWM IC for the entire board...but i can't seem to find the datasheet for it! :/

it says 3528 251 I721C

This isn't a data sheet but maybe you can get more information from the supplier.

Link

OK i think FJ 3528 is the number, all other referances to this chip the other numbers change only the top number stays the same. This seems to be a custom chip. Andy