| 摘要 |
PURPOSE:To obtain a stable output even if input and output voltages approximate each other very close, by giving a function by which a switching regulator is switched to a series regulator when the input voltage is lower than a prescribed voltage. CONSTITUTION:When an input voltage V1 is higher than an output voltage V0, a relay RL is not operated, and a switching transistor TR2 is connected to a comparator 8 as hown in figure, and the output voltage V0 is kept constant indendently of the fluctuation of the input voltage V1. When the voltage V1 drops to approximate the voltage V0, the relay RL is operated, and the TR2 is connected to a differential amplifier 22. In this case, the differential voltage between a reference voltage ES of a Zener diode and a voltage obtained by dividing the output voltage by resistance R1 and R2 is amplified by the amplifier 22 and is applied to the TR2 for the purpose of preventing the output fluctuation for connection change. The forward voltage drop is increased (reduced) when the voltage V1 rises (drops), thus obtaining a series regulator which keeps the output voltage constant. |
