| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply that can contribute to reduction of a power source voltage and miniaturization of a chip size by reducing a terminal voltage of a load when powered off. SOLUTION: The power supply 20 comprises an output circuit (an output transistor Qex, an inductor Lex, a diode Dex, a capacitor Cex, and an output control circuit 213), which converts an input voltage Vin into a predetermined output voltage Vout and supplies the voltage to a load (light-emitting diode rows LED1-LED4), and a constant current driver 214, which supplies a predetermined drive current to the load. This power supply, which controls an output voltage Vout by an output circuit so that the minimum value of the terminal voltages VL1-VL4 coincides with a predetermined reference voltage Vref, is provided with a power-off controller 211 that stops the drive of the constant current driver 214 when a predetermined period of time elapses after the drive of the output circuit is stopped when the drive of the load is stopped. COPYRIGHT: (C)2008,JPO&INPIT
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