Patent ID: 6522034
Filing Date: 2003-02-18
Classification: B60L,H02J,H02P,Y02T

Abstract:
A switching circuit for use in a multi-voltage level power supply unit for supplying a first voltage and a second voltage lower than the first voltage, the switching circuit comprising:a first relay designed to operate at the second voltage during transition periods between open to closed states and closed to open states, configured to control a load current; a first semiconductor device having a first control electrode, a first main electrode for receiving the first voltage, a second main electrode connected to the first relay, configured to conduct the load current from the first main electrode to the second main electrode so as to supply the load current to the first relay so that the load current can be controlled by the first relay; and a control unit connected to the first control electrode for, during the transition periods of the first relay, providing a first control signal to the first control electrode so as to generate a first on-state interelectrode voltage between the first and second main electrodes, the first on-state interelectrode voltage corresponding to a difference between the first and second voltages, and providing a second control signal to the first control electrode so as to generate a second on-state interelectrode voltage lower than the first on-state interelectrode voltage during steady state periods of the first relay.