Safety is paramount, agreed. The entire design will be protected/isolated,= its switching AC voltage as well so must be insulated from the user. The = demo board has a large amount of copper for heat sinking, but adding a heat= sink might be better way of doing it in a compact area. = Martin...thanks for the offer on the paper but I have to complete the des= ign by the end of the month, so no time for "experiments" Bob Axtell wrote: alan smith wrote: > Came across this design, even better than the ON Semi that still requires= a transformer. > = > http://www.supertex.com/pdf/datasheets/SR08x.pdf > = > You can get a regulated 3.3V or 5V @60mA, plus an adjustable 9-50VDC 100m= A(adjustable using a divider network to a feedback pin) output. Downside is= its only 55% efficient, but for the size its not bad. And I think...is a b= it better than just the LC type supplies, not as cheap but perhaps more rob= ust. > = > Anyone care to comment...good and bad on this app note? > = > My only issue is I need 5V and 3.3V so looks like the 9V gets dropped usi= ng either an LDO or small switcher. I need 50mA at 3.3V, and 30mA at 5V > = > -Al > > = > --------------------------------- > Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rate= s starting at 1=A2/min. > = Maxim tried this sometime back without success. At 55% efficiency, a quantity of heat still must be bled away so a large = heatsink will still be needed... something that may be touched by the = user. I think for just the 3.3V output it might be OK. Safety must be = paramount here. --Bob -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist = --------------------------------- Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rates= starting at 1=A2/min. -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist