18 Jun
2009
18 Jun
'09
6:04 p.m.
blstuart at bellsouth.net wrote:
I just checked what I have. My 1977 Voltage Regulator
Handbook doesn't list it at all.
My 1980 Linear Databook
includes a couple of switchers among the typical applications.
That would suggest such a data sheet would have to be
around 1978 or 79.
The earliest example I have at hand for the 723 is the manufacturer's schematic
for the Wang 520 calculator. The power supply page with two 723's on it (used
just in linear mode), is dated early 1971. Perhaps the earlier handbook was
from a manufacturer that didn't 2nd-source it.
It was a National book, but I can believe that it could
well be incomplete. That's why I equivocated and said
it suggested a time frame. The existence of it in these
earlier systems clearly moves the lower bound.
BLS
I've
heard a rumour that early 723 data sheets only show it as a
linear
regulator, the designers didn't realise it could be used as a
switcher.
After it started getting used in the latter configuration, example
circuits were added to the data sheet. Does anyone have an early
723 data
sheet which doesn't show a swtiching regulator circuit?
I have some pretty old NS databooks; I will check.