MarkT:
cjdelphi:
Lefty option 2 sounds intriguing... would a couple of resistors do a similar thing having the resistors tied to give 1 output?Diodes have a fairly constant voltage characteristic without allowing one regulator to back-feed the other - resistors
are not going to do a great job here I think.To be practical you'd use schottky diodes (forward voltage 0.4 to 0.5V max, not 1N4001's which have a forward voltage of
1.1V or so). These days schottky diodes are pretty much used for everything (unless very high voltage / high temperature,
or if low reverse leakage matters). Schottky's have considerable reverse leakage at higher temperature...
Agreed, schottky would be better. However adding a series diode in the ground pin line of the regulator chip is a very simple trick to 'compensate' for the output diode(s) voltage drop.
Lefty