On 3/9/07, Robert Ammerman wrote: > I have studied and have a pretty good idea about how switching power > supplies work. However, what I have seen is designed to create a regulated > voltage output. > > What I need is the ability to have a regulated current output. In this case > about 800ma. The source voltage is 170DC (half bridge from 120VAC) and the > expected voltage across the load is between 2 and 5 volts (or preferably up > to 10 volts). 5V and 10V at 800mA is not the same. Keeping dissipation small on the current regulator is the key. Definitely I'll vote for an 170VDC to 6VDC converter followed by a constant current generator. Power dissipation will be maximum (6V-2V)*0.8=3.2W and minimum (6V-5V)*0.8A=0.8W. More power at 10V load voltage swing. At 1 inch cubic dimension is quite difficult to evacuate the heat, so probably will require external heatsink. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist