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Is it safe to "bypass" (as in circumvent) a linear voltage regulator by applying a voltage to its output (equal to the specified regulator output voltage), while the regulator input remains unconnected?
I have a circuit which is powered by a 6V adapter (a "wall-wart"). The 6V adapter supplies the input of an ADP3338 (through a diode), which delivers 5V regulated output to the rest of the circuit.
Now I am interested to see how the circuit would respond to a different 5V supply. That is, I would like to power the circuit from an external 5V supply, bypassing the ADP3338 (without otherwise tampering with the circuit).
My idea was to simply connect an external 5V supply to the output of the ADP3338, while leaving the input (6V from adapter) unconnected. This is illustrated below:
However, I am not sure if this is safe, or if it will destroy the regulator, or if it will mess with the rest of my circuit in some other way.
The functional block diagram from the ADP3338 specs, depicted below, shows a resistive voltage divider between GND and OUT. I measured 0.7M Ohms between these two pins, so I guess that should not be an issue. But how will the rest of the regulator circuitry react?
Thanks for your help.