Hippynerd:
Somehow I got lost on the math there DC. 1.28 * 1.28 = 1.6384, divide by 4 and you get .4096.
How do you come up with .5 watt?
See reply #83. I suggested a maximum of 1W for a TO220 mosfet with no heatsink, and 0.5W for a mosfet in a smaller package.