Hi Richard,
What switching frequency did you select for the webench design?
TI has an existing reference design, PMP4820, www.ti.com/.../PMP4820 , which matches you requirements.
Regards
Peter
I think the best place to start is in the UCC28600 product folder. This application fits perfectly within this device's intention. http://www.ti.com/product/ucc28600 This is our popular "Green Mode" controller for low power offline flyback design.…