| 摘要 |
PROBLEM TO BE SOLVED: To suppress voltage ripples by stopping a capacitor which applies voltage through a resistor with the detection of recovery voltage of a commercial power source, and stopping the second DC-DC converter gradually, according to the terminal voltage of the capacitor. SOLUTION: When commercial power recovers from power failure, a photodiode 6 is turned on. Therefore, a capacitor(CS) C1 is charged through a resistor R1. The terminal voltage of CSC1 is added to CSC2 and the base of a transistor(Tr) 4 through a resistor 3 and a diode D2. Raising the terminal voltage of CSC2 will turn on Tr4 and turn off SW2 with the timing of shortening the ON period of a switching element(SW) 2. By the terminal voltage of the CSC2 going up according to the time constants of R1.C1, the timing of turning off of SW2 becomes quick, and if it goes up furthers, SW2 continues OFF condition. |
