Quote:
However, if there is a higher voltage low Z supply, elsewhere in the apparatus or in some external device connected to it (or even just a moderate size capacitor charged to a higher voltage) and it gets inadvertently connected to the regulator output, it is usually very destructive to the pass transistor, ...
The best way to avoid this is a series (rather than a shunt diode) on the supply output and that can be included in the feedback loop so the diode's temperature coefficient and voltage drop can be compensated out.
|
Neat solution. For a few pennies, the whole shebang can be saved from this failure mode. The external cap charged to a higher voltage is an easily imagined scenario.