I would say that two 48V isolated, controllable supplies in series would be the best starting point. Otherwise, I'd probably look at flyback or half/full bridge converters (PWM driving a transformer). You should be able to find some reference designs along these lines which will do what you want or easily be modified to do what you want. Another thought is to use an AC line transformer with multiple taps followed by a linear regulator. You select the lowest voltage tap which still allows you to stay in regulation and you can get decent efficiency. Sean On Mon, Jan 19, 2015 at 2:06 PM, Dwayne Reid wrote= : > Good day to all. > > I'm working on a project where I need an power supply adjustable over > the range of < 15Vdc through 100Vdc at 300mA max. I've done tons of > adjustable supplies in the past: good old LM723 linear regulator, > adjustable 3-terminal regulators, single-chip switch-mode supplies > (Nat Semi Simple Switcher series). But nothing with this high a > voltage. Input supply is 120Vac nominal. > > I greatly prefer to stay with Switch Mode for efficiency reasons. My > first thought was to simply grab an open-frame SMPS from Meanwell or > whoever and make the control circuit adjustable. But I'm not finding > any open-frame supplies in that 100Vdc output range and I really > don't want to control two independent 48V supplies in series. > > I've looked at lab supplies - there are many available from Digikey > but the price is prohibitive (a grand plus). > > The total projected usage over this project's lifetime is perhaps a > few dozen units. > > I don't really care at this point whether I build something suitable > or purchase. > > I'm looking for suggestions before I go blindly down the path that > looks the easiest at this point in time. > > Many thanks! > > dwayne > > -- > Dwayne Reid > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > www.trinity-electronics.com > Custom Electronics Design and Manufacturing > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .