| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply circuit which does not need a separate compensation circuit and includes a charge pump circuit that carries out soft start using an excess voltage protective circuit smaller in circuit scale than a regulator, and to provide a power supply system using the power supply circuit. Ž<P>SOLUTION: The excess voltage protective circuit 3 determines that an output voltage VOUT rises to an excess voltage when a divided voltage VSENSE given by dividing the output voltage VOUT rises to a reference voltage VREF or higher voltage and causes the charge pump circuit 2 to suspend its voltage-raising operation. It also causes the charge pump circuit 2 to start its voltage-raising operation when the divided voltage VSENSE drops below the reference voltage VREF. At the start of the system, a reference voltage generating circuit 4 slowly raises the reference voltage VREF at a given speed or lower speed, and the excess voltage protective circuit 3 carries out control over suspension of the voltage-raising operation by the charge pump circuit 2 in accordance with the result of comparison between the reference voltage VREF and the divided voltage VSENSE to cause the charge pump circuit 2 to carry out a soft start operation. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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