| 摘要 |
PURPOSE:To prevent an output voltage from varying by providing a capacitor and a charging/discharging circuit of the capacitor in the tertiary winding of a transformer for driving a switching element. CONSTITUTION:A switching regulator outputs a constant voltage by connecting a DC power source 1 with a series circuit of the primary winding 3 of a transformer 2 and a switching transistor (Tr) 4, driving the base of the Tr 4 through a voltage controller 11 from the tertiary winding 9 and rectifying and smoothing the voltage induced in the secondary winding 5 by rectifying and smoothing circuits 5, 6. In this case, a capacitor 20 is connected through resistors 10, 19 between one end of the winding 9 and the base of the Tr 4, and the charging/ discharging circuit 21 of the capacitor 20 having diodes 22-24 is provided. Thus, since the Tr 4 is not driven by the voltage of the winding 9 at On time but driven by the capacitor 20 and the capacitor 20 is charged by the voltage of the winding 9 at OFF time of the Tr 4, the base current is not affected by the influence of the variation in power source voltage. |
