| 摘要 |
PROBLEM TO BE SOLVED: To raise stability by preventing the overshoot of an output voltage generated, when a switching operation is resumed in a power supply device having a switching regulator of synchronous rectification system. SOLUTION: The power supply device 100 includes a step-down converter 10, a regulator 12, a PWM signal generator 14, and a bypass switch SW3, and operates by switching the output of the step-down converter 10 and the output of the bypass switch SW3. The error voltage of the output of the regulator 12 is offset in the direction for turning off a switch for synchronous rectification by an offset circuit 20 during a period, in which the input voltage Vin is outputted as it is by the bypass switch SW3. When the output of the power supply device 100 is switched from the bypass switch SW3 to the step-down converter 10 and the step-down operation by the step-down converter 10 is resumed, a switch SW2 for synchronous rectification is gradually turned on from the off state by the offset of the error voltage. COPYRIGHT: (C)2006,JPO&NCIPI
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