Bob wrote... >Has anyone here ever made/seen a variable output switching power supply >(possibly using a PIC as the controller)? Not just a couple of fixed = voltages >(3.3 & 5v), but more like a variable linear supply (like one controlled = by a >simple LM350T circuit). Many of the single-chip switching regulators from companies such as National Semiconductor and Linear Tech are offered in both fixed and adjustable versions; the only difference between them is that the fixed-voltage versions have a trimmed, on-chip voltage divider (connected between the regulator's output and its feedback input) preset for the desired voltage; with the adjustable versions, an external voltage divider sets the output voltage. I'm most familiar with the National parts. Their LM2574 is a 0.5 amp stepdown regulator in an 8-pin DIP; the LM2577 is a stepup (i.e., "flyback") regulator in a variety of package options; both are available in fixed-voltage and adjustable versions. >Since my knowledge of switching power supplies is nearly nill, I'm not = even sure >if this is possible.... Yep. Sure is. Dave -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.