| 摘要 |
PURPOSE:To prevent the occurrence of a defect in a load system due to a noise by synchronizing the switching frequency of an input power source circuit with the system clock generated from the load system. CONSTITUTION:A voltage controlled oscillator 210 oscillates in a peculiar natural frequency until a load system 240 starts operating, and a switching element 103 opens or closes an input power source circuit by the natural frequency. The prescribed voltage is supplied from an output terminal 212 to the system 214, and after the system 214 starts operating, a system clock is inputted from a trip sync terminal 213, the phase difference between the output of the oscillator 210 and the system clock is detected by a phase comparator 211, and the voltage proportional to the phase difference is supplied as a control input to the oscillator 210. Then, a sawtooth wave generator 109, a voltage comparator 106 and a switching element 103 are operated in synchronization with the system clock. |
