| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a controlling means for a charge pump circuit, capable of producing a boosting ratio of 1 and a generating boost voltage, wherein a latch-up phenomenon will not occur, even if output terminals are short-circuited during boosting operation. Ž<P>SOLUTION: The charge pump circuit for driving LEDs includes a current path having a first PMOS transistor that is energized and connects power supply and output, when a first mode with a boosting ratio of 1 is selected; and second and third PMOS transistors, connected in series between the power supply and an output end. The transistors are so connected that the potential of the contact node between both the transistors is equal to the substrate potential of the first PMOS transistor. The charge pump circuit includes a control circuit such that when the output terminals are short-circuited during boosting operation, the third PMOS transistor on the output end side is turned off. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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