Patent ID: 9246474
Filing Date: 2016-01-26
CPC Classification: H03K

Claim Text:
1. A drive circuit for an insulated gate switching element, comprising: a constant current source that generates a constant current; a switching circuit that connects a gate of the insulated gate switching element to a power supply potential side via the constant current source when turning the insulated gate switching element ON and connects the gate of the insulated gate switching element to a reference potential side via a discharge circuit when turning the insulated gate switching element OFF, based on a drive signal; a gate voltage detection circuit that detects a gate voltage of the insulated gate switching element; and a current mode selection circuit that switches a mode of the constant current source from a normal current mode to a low current consumption mode when detecting, based on the gate voltage detected by the gate voltage detection circuit becoming equal to or greater than a predetermined value, that the insulated gate switching element is turned ON, and switches the mode of the constant current source from the low current consumption mode to the normal current mode when the gate voltage detected by the gate voltage detection circuit becomes less than the predetermined value; wherein the current mode selection circuit has a partial resistor having a power supply-side resistor and first and second ground-side resistors, connected between a positive power supply and a ground, and a switching element connected directly to, and in parallel with, the second ground-side resistor, sets a ground-side partial resistance value at a normal value when the gate voltage detected by the gate voltage detection circuit is less than the predetermined value, and sets the ground-side partial resistance value at a low consumption mode resistance value lower than the normal value when the gate voltage detected by the gate voltage detection circuit is equal to or greater than the predetermined value.