Hi,
I need to design 110-120VAC input, 5V/3.5A (~20W) output, isoloated converter. I has to be high efficiency (>85%) due to small package outline and required low temperature rise. Typical flyback converter of 75% efficiency generates too much heat. I am considering forward converter topology with additional transdormer winding at the primary side and I'm looking for a simple, cost effective, controller with lowest external components count possible, like this: http://en.wikipedia.org/wiki/Forward_converter
Can anyone recomend any controller for this kind of topology or other still simple but high efficiency, for that kind of output power range (~20W)?
Topologies with synchronous rectifiers and second controller on the secondary side seems to be expensive and might have too much components for required form factor.
Thank you in advance,
Luaksz