A very belated thank-you to Xiaofan for the link and definition. Sean On Sat, Feb 4, 2012 at 8:48 PM, Xiaofan Chen wrote: > On Sun, Feb 5, 2012 at 8:33 AM, Sean Breheny wrote: >> Hi all, >> >> I keep encountering the term "off-line" in switching power supply >> literature. It seems to refer to power supplies which are intended to >> operate from non-isolated, rectified and filtered AC mains line >> voltage. Do I have this definition correct? I've never actually seen >> the term defined and so far Google has not turned up a definition >> which is relevant to the topic at hand. >> >> Does anyone know the origin of this term? What is the opposite of this >> term? DC-DC converter? "on-line"? (seems like it should be on-line but >> I'm not even sure what this would mean) >> >> Is it short for "off-the-line" meaning that it is powered by the AC >> mains line? What term is used when the AC input IS isolated and >> stepped-down first by a 60 (or 50) Hz transformer? I have seen such >> designs, mainly for older equipment which is designed for use at high >> mains voltages like 480V 3-phase. >> >> Thanks for any wisdom you can impart! > > http://www.smpstech.com/tutorial/t01int.htm > > The PSMA Handbook > ( http://www.smpstech.com/books/bookp.htm#PSMA0001 ) > defines off line power supply as: > > Off Line Power Supply -- > 1) A power supply in which the ac line voltage is rectified and filtered > without using a line frequency isolation transformer. > 2) A power supply switched into service upon line loss to provide power > to the load without significant interruption. Also called Off Line > Switchers (OLS). > > -- > Xiaofan > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .