We are using ADP151 in a dual supply environment. We have one 2.8-3.6V battery supply which is limited to 2.8V by an ADP151 and a 3.3V supply. We want to connect the 3.3V supply to the ADP151s output through a diode. The output voltage will be about 3.1V when powered through the 3.3V supply. When the 3.3V supply is not present the ADP will supply 2.8V from the battery.
question: what will happen when the battery is completely drained and the external 3.3V is supplied? Will this lead to a current flow from the ADP151 output to its input? Or would there be any other reason why this would lead to damaging the ADP151?
I would usually add an extra diode at the output of the ADP151, but that would cost me too much of a voltage drop.