Patent ID: 6356423
Filing Date: 2002-03-12
Classification: H02H

Abstract:
An apparatus for protecting an electrical load from excessive current, which apparatus comprises:a semiconductor switch for connecting the electrical load to a source of current and having a control input; a current sensor coupled to the semiconductor switch and producing a sensor signal indicative of a magnitude of current flowing to the electrical load; and a control circuit connected to the current sensor and the semiconductor switch and responding to the sensor signal by producing a control signal that is applied to the control input, the control circuit having a first mode of operation when the magnitude of current is less than a first threshold wherein the semiconductor switch is maintained in a continuous conductive state, a second mode of operation when the magnitude of current is greater than the first threshold and less than a second threshold wherein the semiconductor switch is rendered non-conductive after a predefined period of time, and a third mode of operation when the magnitude of current is greater than the second threshold wherein the semiconductor switch is alternately pulsed conductive and non-conductive to limit the current through the load to less than the second threshold.