| 摘要 |
A power source device capable of improving the power conversion efficiency at a light load independent of an input power source voltage is realized. For example, a clock signal is output from a common control unit to a PWM-mounted drive unit including a reverse-current detection circuit in addition to a peak current control method. This clock signal is selected by a mode setting signal from either of a clock signal with a constant frequency or a clock signal which is generated via a one-shot pulse generation circuit every time an output voltage at an output power source node decreases. When the latter is selected, the switching frequency at a light load decreases and the power conversion efficiency improves. Furthermore, the peak current control method can reduce the input power source voltage dependence of the switching frequency.
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