Abstract: A power efficient circuit for charging the gate of a transistor switch to a charge-pumped voltage level in excess of a supply rail voltage is provided. The circuit includes a current-controlled oscillator which generates an oscillating waveform that drives a capacitive charge-pump circuit. The circuit monitors the gate voltage of the transistor switch and reduces the frequency of the oscillating waveform, thereby reducing power consumption, when the gate voltage exceeds a frequency switching value indicating that the transistor switch has been sufficiently turned so as to allow the circuit to enter a micropower mode.