| 摘要 |
PURPOSE:To improve efficiency by prohibiting the operation of either a boosting circuit or a step-down circuit which is unnecessary. CONSTITUTION:A voltage step-down operation is performed by making and braking the current from a positive voltage input terminal 1 by using a switching element 2, while a boosting operation is performed by making and braking a switching element 3, and a required voltage is outputted to an output terminal 4. Each operation of these switching elements 2-3 is exclusively controlled at a switching control circuit 5 by a pulse width modulation system. The output voltage Vo through reference voltage source 6, a voltage divider 7 and a buffer 8 is inputted to an error amplifier 9, an error amplifier 10 for a voltage step-down operation. The control voltage inside of each circuit is monitored each other at the part of a boosting operation circuit and the part of a voltage step-down operation circuit, and a flip flop for prohibiting an unnecessary operation each other is formed. Accordingly, the inside loss is reduced as well as the decrease in heat generation. |
