| 摘要 |
PROBLEM TO BE SOLVED: To detect a load abnormality accurately in a power supply control circuit which controls the power supply to be cut off in the case of the load abnormality. SOLUTION: Before a power is supplied to a load, a switch 4 is opened to have a load impedance measurement mode. In this mode, a minute current is supplied to the load through a current limiting resistor 3 to measure a load impedance. At that time, a load terminal voltage is compared with a reference voltage by a voltage comparator 5 and, if the load terminal voltage is higher than the reference voltage, it is decided to be normal and a switch 4 is closed to supply a power and, if the load terminal voltage is lower, it is decided to be abnormal and the switch 4 is kept open. Therefore, the power is not supplied to the load 7 if it is abnormal. |
