Patent ID: 8315027
Filing Date: 2012-11-20
Classification: H03K

Abstract:
1. A switch circuit having an overcurrent detection function for detecting an overcurrent flowing into a single wire harness, which is connected with a plurality of load elements equipped to a vehicle, the switch circuit comprising: a switching element connected to the wire harness; a control circuit configured to control activation and deactivation of the switching element; a threshold circuit assigned with a first overcurrent threshold and a second overcurrent threshold, the second overcurrent threshold being less than the first overcurrent threshold; a first overcurrent detecting circuit configured to: a second overcurrent detecting circuit configured to: an overcurrent determination circuit configured to determine that an overcurrent flows into the wire harness and cause a control circuit to deactivate the switching element when inputting at least one of the first time-up signal and the second time-up signal, wherein the threshold circuit includes a plurality of resistor elements connected in series, the threshold circuit is configured to cause the plurality of resistor elements to generate divided voltages including a first overcurrent threshold voltage and a second overcurrent threshold voltage, which respectively correspond to the first overcurrent threshold and the second overcurrent threshold, the first overcurrent detecting circuit includes: the second overcurrent detecting circuit includes: a first reset circuit configured to reset measurement of the time period of the first overcurrent timer when an electric current flowing into the wire harness is less than the first overcurrent threshold according to the comparison result of the first comparator; and a second reset circuit configured to reset measurement of the time period of the second overcurrent timer when an electric current flowing into the wire harness is less than the second overcurrent threshold according to the comparison result of the second comparator.