A regulator circuit and method are disclosed for a system. The regulator
circuit may include a compare circuit for comparing a first supply
voltage to a predetermined voltage level and generating an enable signal
based upon the comparison. A selectively enabled voltage regulator is
adapted to make available a predetermined current level at a regulated
voltage when enabled by the compare circuit. When disabled, the voltage
regulator circuit is prohibited from providing current. The voltage
regulator may include an output transistor that is normally biased in a
saturation mode of operation and is deactivated by the enable signal. By
controlling the output transistor based upon the output of the compare
circuit, the need for a relatively large transistor for connecting to the
first supply voltage is eliminated.