Matt,

Don't get me wrong, but if you aren't an experienced power supply designer, designing your own switching power supply may not be a good idea. It will most likely me less expensive and you will most likely get a better working supply if you buy one off of the shelf. I am not a power supply designer, but my experience with them has taught me to leave it to the experts. Switching supplies are amazingly complicated. (Many of the experts have a PHD in magnetics, power systems, etc.) Most people can design a supply and get it to work, but it is difficult to get the design to be comparable to an off the shelf solution.

The only thing I would suggest is using a "predesigned" solution such as Maxim offers. They have ICs to control the whole thing, and the datasheets will lead you in the right direction for components. The MAX668 may fit your needs. Beware of EMI.

Hope this helps.

Cory Spackman