| 摘要 |
PROBLEM TO BE SOLVED: To prevent an AC input power supply interrupt signal from being transmitted to a load, as long as an output voltage is maintained and the electronic equipment on the load side is operable, by detecting the presence of AC input voltage and the voltage across terminals of an input smoothing capacitor and a load current, and calculating the timing of input interrupt signal transmission. SOLUTION: A power circuit comprises a single-phase, full-wave rectifier 2, a smoothing capacitor 3 and a converter 20, and supplies a load (electronic equipment) 10 with power of prescribed voltage. The power circuit is provided with an AC input interrupt detecting circuit 6 which detects interrupt of AC input power supply 1, a current (power) detecting circuit 8 which detects load current, a resistance 4 for detection which detects the voltage across terminals of the smoothing capacitor 3, and a CPU 7. When the interrupt of the AC input power supply 1 is detected, the CPU 7 estimates the hold time of output voltage using the value of the voltage across terminals of the smoothing capacitor 3 and the value of load current, and transmits an interrupt signal to the load, when a time obtained by subtracting the time required for processsing on the load 10 side from the estimated time has elapsed. |
