| 摘要 |
PROBLEM TO BE SOLVED: To suppress the cost increase of a device which executes a power supply interrupt processing, when a power supply is interrupted and simplify the configuration of the device. SOLUTION: A power supply circuit 1 which receives a commercial power supply and outputs a DC voltage has two output systems, i.e., 5V system and a 12V system. A large capacity capacitor C1 and a small capacity capacitor C2 are connected in parallel to the output A of the 5V system and the output of the 12V system respectively. When the commercial power supply is interrupted, the 12V system DC voltage outputted to a voltage detection IC5 is made to decline faster than the 5V system DC voltage supplied to a CPU 2, etc., and gives the CPU 2 a processing time long enough to treat the interrupt. With such a configuration, a backup power supply for the CPU 2 can be dispensed with. |
