| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress loss by obviating the need for detecting the voltage of an input current, and also to arrange it so as not to enlarge ripples by adopting a current continuity mode, thereby avoiding enlargement of a device. Ž<P>SOLUTION: A switching power unit by the current continuity mode is provided with an error amplifier 26, which amplifies and outputs an error between a detected DC output voltage and a set value, a current detector 28, which detects the current that flows to an inductor 4; a holding circuit 24, which holds the peak value of the detected current; and a multiplying circuit 23, which limits the minimum value of the current flowing to the inductor 4, according to the peak value, and circuits 21 and 25, which determine the ON time of a switching element 5, etc. When the current flowing to the inductor 4 falls below a minimum value, the switching element 5 is turned on; and then, when a certain ON time lapses, the switching element 5 is turned off. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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