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!

Sean
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