On 10/12/2011 12:05 PM, William R. Walsh wrote:
What I really want to know, though, is whether or not a drop-in
replacement with more current delivering capability than the LM340 or
78xx series exists.

Actually, it sounds more like they blew the design by having too
much input voltage for the output voltage and current.

As a modest example of what I mean:
18V input 12V output at 1 amp. This is 6 watts dissipation at
the regulator package.
24V input 12V output at 1 amp. This is 12 watts dissipation
at the regulator package.

http://www.datasheetcatalog.org/datasheets2/52/529144_1.pdf

Doesn't specifically give a voltage drop vs output current
derating curve. But I would think that adding a bit of series
resistance to the input side and letting some of the waste
heat go away there would go a long way towards extending the
life of the regulator package.

Jeff

--
"Everything from Crackers to Coffins"