UCC2897A: Active clamp flyback converter

Yamaguchi,

UCC2897A can be used for active clamp forward or flyback topologies. Due to the high VDS stress on the main power MOSFET, off-line, HV flyback will benefit most from the active clamp and this is why we see so many dedicated off-line AC/DC active clamp PWM controllers. UCC2897A is targeting telecom input voltage where the benefit to the power MOSFET is not as significant in the flyback topology. Our UCC2897A  literature, design tools and reference designs are focused on the active clamp forward but apart from the design equations used for the power stage and the choice of SR on the secondary, the UCC2897A can be used to control either. Here are some recommended tip:

1. Use TI Power Stage Designer to design the power stage
2. Search TI Reference Designs using keywords such as UCC2897A and "Active Clamp Flyback." If you search on DC, Active Clamp Flyback, you may find design examples that use other controllers as well.
3. Incorporating Active Clamp Technology to Maximize Efficiency in Flyback and Froward Designs, SLUP262 is an excellent paper from the 2010 TI Power Design Seminar. This paper gives a detailed comparison of the flyback and forward with design examples and some good literature references at the end of the paper.

Regards,

Steve M