| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a gate drive circuit for a semiconductor switching element, capable of suppressing generation of abnormal voltage between main terminals at turn-off, by a simple configuration.SOLUTION: The same voltage as a voltage Vcc is inputted to a signal input terminal 7 as an off signal, and a voltage between the signal input terminal 7 and a terminal 6 becomes zero. A MOSFET 2 is turned off, and a MOSFET 3 is turned on. Electric charge stored in a gate is discharged as a gate current J1, and a semiconductor switching element 1 is opened. A voltage at the opening is detected by resistors 31 and 32 for voltage division. When the voltage becomes larger than a reference value, a voltage at a connection point 10 is forcibly reduced by an operational amplifier 5, and an injection current J2 is injected to a connection point 11 by an operational amplifier 4 so as to equalize the respective both-end voltages of a resistor 38 and a resistor 37 to suppress the gate current J1, and thereby, turn-off speed of the semiconductor switching element 1 is reduced to prevent generation of abnormal voltage. Since the gate current J1 is suppressed due to the injection of the injection current J2, a configuration for suppressing abnormal voltage can be simplified.</p> |
