Gate driving circuit

Abstract

To obtain a gate driving circuit in which rising of a constant current of a constant current circuit is fast and power saving is achieved, the gate driving circuit includes: a constant current driving circuit (28) for supplying a constant current; a gate terminal of a power semiconductor element (1), which is connected to an output terminal of the constant current driving circuit; a comparator (22) for comparing a voltage at the gate terminal with a predetermined voltage value and outputting a signal indicating that the voltage is higher than the predetermined voltage value; and a driving control section (20) for increasing a current from the constant current driving circuit (28) in response to a signal for turning on the power semiconductor element (1), and reducing the current from the constant current driving circuit (28) in response to the signal from the comparator (22).

Description

technical field [0001] The present invention relates to a gate drive circuit for driving power semiconductor elements. Background technique [0002] In a conventional gate drive circuit of a power semiconductor element in a load driving device, a constant current circuit and a current mirror circuit are used to drive a constant current through a gate terminal in order to drive an insulated gate transistor. In addition, in order to switch the current value of the constant current circuit, a switch is used in series with the constant current circuit (for example, refer to Patent Document 1). [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-318713 (Fig. 1) [0004] In the conventional gate drive circuit, when the insulated gate transistor is turned on, the rising speed of the constant current circuit is limited, so the current at the gate terminal cannot immediately become a constant value. In addition, in switching the current value of the constant...

AI Technical Summary

Problems solved by technology

[0004] In the conventional gate drive circuit, there is a limitation in the rising speed of the constant current circuit when the insulated gate transistor is turned on, so the current at the gate terminal cannot be immediately become a constant value

In addition, in the current value switching of the constant current circuit, a switch is used in series with the constant current circuit, and the constant current circuit must increase the current to a predetermined current value from a non-operating state, so the rise of the constant current may be slow.

Therefore, if the threshold voltage (VGEth) of the gate terminal varies, the conduction loss will vary, so there is a problem that thermal design with a large margin is necessary, and efficient thermal design cannot be performed.

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