| 摘要 |
PURPOSE:To enable to be applied to a control circuit necessary for a high power voltage by providing switching means for supplying an input power as a power for a drive circuit when the supply voltage from a DC/DC converter to a stabilized power source is lower than the input power voltage. CONSTITUTION:A comparator 2 starts operating by applying an oscillation signal from an oscillator and driver 6 to supply an output to a stabilizer 5. Since the output voltage of the comparator 2 is highly selected as compared with the voltage of an input power source 1, a base current of a transistor 8 through a diode 9 does not flow, and the transistor 8 is accordingly interrupted. Simultaneously, a reference voltage is applied to a controller 7, and the output voltage of the comparator 2 is gradually converged to the normal value. Thus, even if a control circuit necessary for a power voltage higher than the input power is used, a normal operation can be obtained. |
