| 摘要 |
PROBLEM TO BE SOLVED: To provide a suitable switching system on a DC/DC converter switching a control system of an output voltage. SOLUTION: In the DC/DC converter, a transistor where a source and a drain are arranged, and an inductor are installed on a path connecting an input node and an output node. A rectifier is arranged between the node between the transistor and the inductor, and ground. A capacitor is installed between the output node and ground. A semiconductor device is provided with: a detecting circuit for detecting voltage of the node between the transistor and the inductor; and a control circuit whose control mode is switched to a PWM mode or a PFM mode in accordance with voltage detected by the detecting circuit, and which outputs a control signal controlling an ON/OFF operation of the transistor with respect to a gate of the transistor. COPYRIGHT: (C)2009,JPO&INPIT
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