you do not want a linear reg. - it will dissipate nearly 9 watts at 250mA
A switcher will cost less than the heatsink!

On Thu, 8 May 2003 02:05:05 PDT, you wrote:

>    Three things I can think of for +40V to +5V...
>
>    (1) Since you're considering a linear reg, perhaps try to do this in
>    two steps ... drop to say 15V then again to 5V with a second reg.  =
BUT
>    that assumes that you can find a higher-voltage-output regulator =
that
>    will allow 40V in.
>
>Hmm.  The popular and cheap LM317 (variable 3-terminal voltage =
regulator)
>doesn't require that the reference voltage be ground.  There are =
examples
>in the the datasheets/appnotes of using them as regulators for quite =
high
>voltages...
>
>BillW

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics