| 摘要 |
<P>PROBLEM TO BE SOLVED: To shorten a startup time of a switching converter. <P>SOLUTION: A power supply device that transforms DC input voltage by performing a switching control to charge/discharge an inductor (1) and smooths the transformed voltage using a capacitor (6) to obtain DC output voltage comprises: a transistor (4) for synchronous rectification connected between the inductor and the capacitor; a current determination circuit (30A) determining if current flowing through a transistor is less than lower-limit current; and a control circuit (40) operating the transistor in a constant current operation while current flowing through the transistor is more than the lower-limit current, and operating the transistor in a rectification operation when the current becomes less than the lower-limit current on the basis of determination result of the current determination circuit. <P>COPYRIGHT: (C)2012,JPO&INPIT |
