Method and system for allowing a power supply circuit to use a small

Abstract

A method and system for allowing a power supply circuit to limit inrush current and to use a small current specification switch. The power supply circuit comprises a transformer that receives a power signal from a primary circuit and supplies power of a selected voltage to a secondary circuit, to which a load is coupled. The primary circuit comprises a rectifier for providing a rectified power signal to the transformer, a power supply controller for controlling the transformer, and a small current specification switch coupled between a kick resistor and the power supply controller, where the kick resistor functions to activate the power supply controller when the circuit is first turned on. By coupling the switch between the kick resistor and the power supply controller, the present invention not only utilizes the high impedance kick resistor to limit inrush current through the switch so that the switch can have a small current specification, but also ensures that current to the power supply controller is cut off when the switch is open. Thus, when the load is powered off with the switch open, no wattage is dissipated by the power supply controller either and total power consumption of the circuit is thereby minimized. The primary circuit optionally comprises a voltage limiter coupled to protect the power supply controller. Additionally, the primary circuit optionally comprises an impedance element coupled to further limit inrush current.