Patent ID: 6989976
Filing Date: 2006-01-24
Classification: H02H

Abstract:
1. An overcurrent protection circuit comprising: input and output terminals connected to a driving power source and an external electric equipment, respectively; a relay including a contact point and a coil for opening and closing the contact point in response to a predetermined current passing through the coil to control power supply from the driving power source to the external electric equipment; a first transistor element coupled in series with the coil for controlling current flowing through the coil in accordance with a predetermined switching control signal; a bias voltage output circuit including, a second transistor element for controlling supply of the switching control signal to the first transistor element based on the bias voltage, wherein the resistance value variable element is a PTC element and the bias voltage output circuit is configured in a manner that one end of the PTC element is grounded and other end thereof is coupled to one end of the bias voltage adjusting resistor, and other end of the bias voltage adjusting resistor is coupled to the bias power source.