| 摘要 |
PROBLEM TO BE SOLVED: To provide an injector drive device surge protection device capable of dispersing transient heat generated by a surge voltage of an electromagnetic coil of an injector and appropriately protecting a field effect transistor without using high withstand voltage process or the like while promptly stopping an injector injection process similarly to a conventional technique when current is applied to change the electromagnetic coil of the injector from an ON-state to an OFF-state.SOLUTION: A MOS transistor M1 is connected in series to an electromagnetic coil L1 of an injector 4. A protection circuit 5 is connected to a common connection node N1 common to the MOS transistor M1 and the electromagnetic coil L1. The protection circuit 5 includes: a forward diode D1; backward connection Zener diodes Dz1 to Dz3; voltage dividing resistors R3 to R5; a MOS transistor M2 having a gate to which divided voltages of the voltage dividing resistors R3 to R3 are input; a first resistor R1 connected between a cathode of the diode D1 and a drain of the MOS transistor M2; and a second resistance R2 connected between a source and a ground of the MOS transistor M2. |
