| 摘要 |
PURPOSE:To reduce the load of a main CPU and the hardware and to prevent the power consumption by detecting the drop of the main power supply voltage less than a fixed level through a subsidiary CPU to inform it to the main CPU and cutting off the supply of power with the voltage drop lower than the detected drop of voltage. CONSTITUTION:The subsidiary CPU 7 fetches the voltage of a main power supply 9 after A/D conversion and detects the drop of this voltage less than a fixed level to inform this voltage drop to the main CPU 1. When the CPU 7 detects the another fixed level of voltage of the supply 9 is reduced less than the other fixed voltage having lower voltage than a fixed level, a signal is delivered for the discontinuation of working of the CPU 1. At the same time, the selection is inhibited for memories 2 and 3 as well as an I/O device 6 for cut-off of the power supply to a circuit from the supply 9. In such a way, the voltage drop of the supply 9 is informed without applying the load to the CPU 1 and the hardware. In addition, the supply of power is interrupted to the supply 9 after the protection is secured for a memory. This prevents the consumption of the power supply 9. |
