Patent ID: 7868605

Claim:
Power regulator circuitry on an integrated circuit, comprising: an output at which a regulated output voltage is provided; a regulated power supply circuit that is connected to the output and that is turned on and off using a first digital control signal; a switch-based power supply circuit that is connected to the output and that is turned on and off using a second digital control signal; and control circuitry that deasserts the second digital control signal to turn off the switch-based power supply circuit only after asserting the first digital control signal to turn on the regulated power supply circuit, wherein the regulated power supply circuit comprises an operational amplifier having an enable input, wherein the enable input of the operational amplifier receives the first digital control signal, and wherein the switch-based power supply circuit comprises: a digital switch containing a plurality of serially connected transistors each of which has a gate; a gate control circuit that receives the second digital control signal and that generates corresponding gate control signals for the gates of the transistors; and a level shifter in the gate control circuit that receives the second digital control circuit and that outputs at least one of the gate control signals.