Patent ID: 7365579
Filing Date: 2008-04-29
Classification: H02M,H03K

Abstract:
1. A gate driving circuit for a driving target device operable with a DC power source, comprising: a reactor having a set inductance; a variable current carrying path which switches a current carrying path among the driving target device, the DC power source and the reactor to perform an operation in one of plural operation modes including at least a hold mode in which a gate of the driving target device is directly connected to a positive electrode or a negative electrode of the DC power source to hold the driving target device in an ON state or an OFF state, a preparation mode in which the ON state or the OFF state of the driving target device held in the hold mode is held and a closed loop for causing a reactor current to flow through the reactor from a positive electrode side terminal to a negative electrode side terminal is formed between the DC power source and the reactor, and an execution mode in which a closed loop for causing a gate current having a magnitude equal to a reactor current to flow in or to flow out is formed between the reactor and parasitic capacitance of the gate of the driving target device, the variable current carrying path including a backflow path for causing the reactor current flowing through the reactor to flow back to the DC power source when a gate voltage of the driving target device deviates from a preset allowable voltage range; and a drive control part which sets the operation mode of the variable current carrying path to the hold mode and holds the ON state or the OFF state of the driving target device, and further switches the operation mode in sequence of the preparation mode and the execution mode, and realizes turn-on or turn-off of the driving target device.