Question
In the datasheet of ADP3330 there is no indication what is allowed for reverse
voltage, i.e. if the output voltage is greater than the input voltage(in case
input power is disconnected and the output capacitor still has voltage). Is it
necessary to put a diode from output to input to protect the circuitry for
output voltages of 3.3 to 5 volts? Or do you advise again usage of ADP3330
under these conditions?
Answer
The issue with using a part without reverse protection is dependent on what’s
connected to the input of the LDO. If there is other circuitry there that can
be powered by the “body diode” of the LDO will have to carry that current but
if the load is 0 then there is not current just voltage, and that’s not an
issue.
Some parts with reverse protections are the ADP710x and the ADP174x, ADP175x.