| 摘要 |
PURPOSE:To reduce the number of circuit component parts and lower the cost and improve the precision of detection and enhance reliability, by organizing processing means for detecting the lowering of voltage, with a microcomputer. CONSTITUTION:When a microcomputer 17 is operated, then a timer 17e contained in the computer 17 is count-operated, and detecting informations on the normal or down state of a power source are produced. By a photocoupler 15, pulse cycling on power voltage is produced, and every input of the pulse for interruption command, contents counted with the timer are cleared, and by taking the both end voltage of a shunt resistance 6 connected on the output side of a converter 3, into the microcomputer 17, a comparison time value is set through voltage drop rate on the down state of the power source according to load current. The set value is compared with the count content of the timer, and when the count content is equal to or more than the set value, then it is discriminated that the power source is in a down state, and the lowering of voltage is detected. |
