Quote: Originally Posted by davesaudio2
What would a diode accomplish on the input?
It would isolate short voltage dips/spikes.(think mini-tank)
IN5819 is a 1 amp Shottky diode dropping .3v ish. don't have a 3amp part num offhand
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First off, just want to state again, that I am by no means an expert on these things. But I don't think the diode wouldn't do anything but needlessly drop some voltage and prevent reverse current which should never happen in this particular situation. (I suppose it could if you wired it backwards, but I don't think the regulator would do anything, though wouldn't want to try that theory on my touchscreen)
From my understanding Shottkys are used either for recifying AC due to the quick recovery time or in place of a regular diode where a low drop is desired.
For limiting voltage, Zener diodes are what are normally used. That's what the 16v Zener in the above circuit is for. It provides protection against surges.
I also think that if a diode there would do anything helpful, it would be in one of the circuits in the
datasheet or mentioned in the appnotes.