| 摘要 |
PROBLEM TO BE SOLVED: To reduce a consumption current of a drive power supply circuit for generating a drive voltage in a liquid crystal display or the like. SOLUTION: When a drive voltage Vi is greater than a reference voltage ViH, both signals S3P, S3N of differential amplifier circuits 30P, 30N are set to "L", and signals S4P, S4N of output circuits 40P, 40N are set to "H". Therefore, an NMOS 62 is turned on to lower the drive voltage Vi of a node N6. At this time, a control signal CP is set to "L", and a constant current circuit 20P is inactivated. When the drive voltage Vi is smaller than the reference voltage ViL, a PMOS 61 is turned on to raise the drive voltage Vi of the node N6, and the constant current circuit 20N is inactivated. When the drive voltage Vi is greater than the reference voltage ViL and smaller than the reference voltage ViH, the signals S4P, S4N are respectively set to "H", "L", and the PMOS 61 and the NMOS 62 are turned off while the control signals CP, CN are set to "H" and monitoring is performed by a comparator circuit. COPYRIGHT: (C)2007,JPO&INPIT
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