A bandgap reference voltage circuit includes a bandgap circuit, a start-up
circuit, and a recovery circuit. Upon device power-on, the start-up
circuit provides a start-up current to initialize the bandgap circuit to
a valid state, during which the bandgap circuit generates a substantially
constant bandgap reference voltage. Once the bandgap circuit is in the
valid state, the start-up circuit turns itself off. If the bandgap
reference voltage falls to a level that causes the bandgap circuit to
enter an invalid state, the recovery circuit turns on and provides a
recovery current to the bandgap circuit that returns the bandgap circuit
to the valid state, after which the recovery circuit turns itself off.