| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately detect the temperature of a load driving circuit at low cost making the most of existing constitution without separately providing exclusive parts for temperature detection and furthermore to secure the maximum driving time of the load driving circuit. <P>SOLUTION: A microprocessor 71 comprises a voltage detecting section 71d, a temperature deriving section 71e, a driving time determining section 71f and a solenoid driving control section 71g. The temperature deriving section 71e applies a constant current in the forward direction of a second parasitic diode 82b by a constant current circuit 76 when first and second switching elements 81, 82 are in the OFF state, and derives the temperature of a solenoid driving circuit 73 based on the forward voltage detected by the voltage detecting section 71d. The driving time determining section 71f determines the drivable time of the first switching element 81 based on the temperature at the driving start of the solenoid driving circuit 73 derived by the temperature deriving section 71e, and on the ensured temperature of the first switching element 81. <P>COPYRIGHT: (C)2008,JPO&INPIT |
