| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive circuit for a voltage drive element that can prevent increase in a surge voltage and a noise independently of a change in a main current while ensuring an advantage of a high switching speed of a voltage drive element such as a MOSFET. SOLUTION: A control signal is applied from a 2nd switch SW2 to a gate of the MOSFET 10 via a 2nd resistor means 5. A 1st resistor means 4 connected to a 1st switch SW1 is placed in parallel with the 2nd resistor means 4. The 1st switch is closed based on the switching of the 2nd switch, after a voltage detection section 6 detects that a terminal voltage of the MOSFET reaches a prescribed value, the 1st switch is open after a delay time set by a delay circuit 8 in response to the main current detected by a current detection section 7. Thus, just after the switching to turn-off of the MOSFET, a changing speed of the gate voltage is kept high at a lower resistance by both the resistor means and then the changing speed of the gate voltage is relaxed in proper timing depending on the terminal voltage and the main current.
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