On 2016-Apr-08, at 11:27 AM, Mouse wrote:
I archive all
data sheets I run across and I found this information
on both TI and Fairchild data sheets for the 78H05, LM340 and LM78XX
devices - it is usually under a heading called Application Hints and
for some reason Fairchild have removed these Hints from the sheets
you quote.
In ALL cases the manufacturers caution that
putting voltage to the
output when the input is not powered CAN DAMAGE THE CHIP.
I have the datasheet PDF for the On Semiconductor version, and I have
been unable to find anything of the sort in it.
http://www.ti.com/lit/ds/symlink/lm340-n.pdf
page 11
I suspect it would be OK if VIN and VOUT were shorted during the procedure (and VIN was
otherwise open or has just a small cap to gnd) as that likely takes care of reverse
current and reverse bias situations being set up on internal junctions, but one
doesn't know for sure unless you examine the internal schematic adequately or test the
device.