Patent ID: 7203046
Filing Date: 2007-04-10
Classification: H02H,H03K

Abstract:
1. An overcurrent detecting device for detecting an overcurrent in a load circuit, the overcurrent detecting device comprising: a DC power supply; a load; a semiconductor switch that controls ON/OFF of the load; a driver circuit that outputs a driving signal to the semiconductor switch; a reference voltage generating circuit that generates a reference voltage; a voltage drop generating circuit that includes a resistor for generating a voltage drop and a constant current circuit that causes a constant current to flow from the source terminal of the semiconductor switch through the resistor for generating a voltage drop so as to generate a desired voltage drop in the resistor; a decision voltage generating circuit that generates, as a decision voltage, a voltage corresponding to a voltage obtained by adding a voltage drop generated in the resistor to a voltage drop generated when the semiconductor switch is turned ON; and a comparing circuit that compares the decision voltage with the reference voltage and outputs a disconnecting command signal of the semiconductor switch to the driver circuit when the decision voltage is greater than the reference voltage.