I have a microcontroller circuit with a 3.3v linear regulator providing power when run by a 5v supply, the circuit can also be run directly from a 3v battery which connects to the output side of the regulator.
I have found that when powered from the battery the regulator consumes 20mA.
Is there a proper way of designing this type of circuit so that when powered by the battery the linear regulator is isolated and doing nothing?
I am trying to keep the circuit design as low cost as possible so I would like to stick with a cheap 3.3v regulator and change the circuit some other way.
Any advice would be appreciated, Thanks