The present invention provides a high efficiency voltage regulator. It includes an input transistor coupled to a voltage source to provide a supply voltage. A detection circuit is coupled to the voltage source and the supply voltage to generate a control signal and an enable signal in response to voltage levels of the voltage source and the supply voltage. A charge pump circuit is coupled to the detection circuit and the input transistor to turn on the input transistor in response to the control signal. A control transistor is connected to the detection circuit and the input transistor to turn off the input transistor in response to the control signal.