| 摘要 |
PURPOSE:To achieve a stable start by applying a reference voltage to the reference input terminal of an error amplifier, by connecting two resistances between a control input terminal and a current detecting resistance, and by connecting a circuit which lowers a voltage at the connection point gradually from a start point. CONSTITUTION:When a switch S1 is opened at a start point, a current from a power source E is charged in a capacitor C13 through a transistor TR1 and a resistance R23, and while its terminal voltage rises toward a voltage E, the base current of the TR1 decreases, so that the TR1 turns off. Consequently, a potential V2 at the connection point between resistances R63 and R53 drops gradually toward a detected voltage, and the output current I0 of a converter 2 rises gradually; when the potential V2 reaches the voltage VD, a diode D1 turns off and the output current I0 becomes a constant current. In this case, a reference input Vref to an error amplifier 2a is made constant and the voltage V2 is lowered gradually to increase the output current I0. |
