>One thing to be aware of is the voltage ratings on these things are only the
>maximum input/output differential. If you plan on placing 57 volts on the
>input
>of the LM317 and regulating it down to 1.2 volts, your going to need an
>LM317HVH. But if you plan on an input voltage of 55 volts, and then regulating
>it to 48v then you're only talking a 7v difference which can easily be handled
>by a standard LM317.
Oh really? That's cool. I guess they're floating ground, huh? That would
be nice actually since the high-voltage parts are majorly-expensive in
singles. ($10 vs. $1) And you're right about the voltage differential of
course...
>Of course an accidental short on the output would cause it
>to exceed it's rating, and I suppose this could happen if the output transistor
>were to short and the output of the power supply was also shorted.
I seem to remember a National Semiconductor databook (pretty old-- late
70's?) that was basically on building power supplies with their LM series
parts. I remember it had a really nice walk-through on transformer
selection... I'll look for it tonight since I (think I) remember they
suggested a few output-short protection methods.
-Clay
Clayton N. Cowgill Engineering Manager
_______________________________________________________________________
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Received on Wed Jan 14 15:39:21 1998
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