| 摘要 |
PURPOSE:To surely protect a load by securing such a constitution where a CPU immediately cuts off the supply of power to the load by a detection signal to avoid the damage of the load in case the power supply voltage is dropped once down to a level lower than the prescribed value of a voltage detecting circuit and hereafter no current flows to the load unless a new release signal is supplied from outside. CONSTITUTION:The power supply voltage is set based on the battery lifetime and the energization of a load 3 and dropped down to a level less than the voltage assuring the CPU working. In such a case, a voltage detecting circuit 5 sends a detection signal to an I/O port of the CPU 1 when the power supply voltage drops down to a level less than the CPU working assuring voltage. Receiving the detection signal, the CPU 1 immediately cuts off the supply of power to the load 3. Hereafter a loop of a state where the supply of power is cut off to the load 3 is kept in terms of a program even though the power supply voltage fluctuates at levels near the prescribed value and the level of the detection signal is repetitively inverted. Thus it is possible to surely protect the load 3 from its damage in case the power supply voltage once dropped down to a level less than the set value. |
