| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply having means for detecting interruption of AC input instantaneously and utilized as a backup power supply. SOLUTION: The power supply comprises an AC input filter 1, an AC input smoothing circuit 2, a DC/DC converter 4 for transforming a DC power supply and an emergency power supply, i.e., a battery 7. When AC instantaneously interruption detecting circuits 5a, 5b for detecting the interruption of external power supply are inserted, respectively, between AND provided for the smoothing circuit 2 and a first line 3a connecting the AC input filter 1 and the smoothing circuit 2 and between GND provided for the smoothing circuit 2 and a second line 3b connecting the AC input filter 1 and the smoothing circuit 2, any one AC instantaneous interruption detecting circuit can detect the voltage with no effect from the discharge of a capacitor included in the AC input filter 1, upon the occurrence of instantaneous interruption of AC input. Consequently, the occurrence of instantaneous interruption of AC input can be detected with no time lag. |
