| 摘要 |
PROBLEM TO BE SOLVED: To detect disconnection of a power source line to a load without changing a driving signal in an abnormality detection device. SOLUTION: An abnormality detection device is provided with a comparator comparing drain voltage of a transistor controlling an operation of the load with reference voltage V1 and an AND circuit to which an output of the comparator and the driving signal are inputted. An output of the AND circuit is connected to a gate of the transistor. When drain voltage is not less than reference voltage in a situation where the driving signal of a high level is inptuted to the AND circuit, gate voltage becomes high, and a part between a source and a drain of the transistor is easily conducted. When drain voltage becomes lower than reference voltage V1, gate voltage becomes low and the part between the source and the drain is difficult to be conducted. When disconnection occurs in the power source line to the load, drain voltage becomes almost zero and thus, a drop of gate voltage is continued. When gate voltage becomes not more than reference voltage, disconnection is judged to occur in the power source line to the load. COPYRIGHT: (C)2004,JPO
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