| 摘要 |
PROBLEM TO BE SOLVED: To provide a solenoid valve drive device accurately detecting a load short circuit even if the drive voltage of a solenoid valve is fluctuated. SOLUTION: In a level setting circuit 50, when the signal level of a current detection value DI is reduced in comparison with a hold low-threshold ItL when an operation mode is a hold mode (Vm: high level), a control signal Vo is changed over to a level to turn on a transistor 31. A change in the control signal Vo is supplied to the transistor 31 at timing delayed by a regulated time Td by a delay circuit 7, and the signal level of the current detection value DI is turned from a drop to a rise at the delayed timing. In an abnormal state with the small inductance of a feeding path, the current detection value DI reaches a peak low threshold IpL during the regulated time Td, and the operation mode is changed over to a peak mode (Vm: low level). In a normal state with sufficiently large inductance, the current detection value DI does not reach the peak low threshold IpL and turned to the rise, thereby maintaining the hold mode. COPYRIGHT: (C)2011,JPO&INPIT
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