| 摘要 |
In a switching regulator, an inductor L 1 (in FIG. 1 ) and an output capacitor C 1 are connected on the output side of a series circuit consisting of a switching element (MOS transistor P 1 ) and a synchronous rectification element (MOS transistor N 1 ), and an N-channel MOS transistor Q 1 is connected between an intermediate point of the inductor L 1 and one terminal thereof. In addition, the frequency of oscillator 2 and the turning ON/OFF of MOS transistor Q 1 are controlled by control unit 1. When output voltage Vout is to be altered, the switching frequency of MOS transistors P 1 and N 1 is increased, and the inductance of inductor L 1 is reduced, whereby a fast output change is permitted. On the other hand, during ordinary constant output voltage operation, the switching frequency is reduced, and the inductance value is increased, whereby high efficiency is attained.
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