On 8/6/06, 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 > 100mA(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 bit better than just the LC type supplies, not as cheap but perhaps > more robust. > > Anyone care to comment...good and bad on this app note? > I've used the older parts (SR03x) before. If you look carefully they are actually linear power supply at each half cycle. That is why the efficiency will not be high. Another problem is that they are not good for DC power supply. You may not be able to add a sufficent large input capacitor. This might be a problem for EMC. You can actually build your own SR08x based on the principles of the datasheet. In fact I came across this type of power supply quite some time ago. However I did not use it for my previous universal power supply design because the problem with heat. I opted to use a real PWM switching converter instead. Still I think it is an interesting circuit if the efficiency is acceptible. Regards, Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist