| 摘要 |
A switching mode power supply apparatus comprising an overvoltage protection circuit is disclosed. The overvoltage protection circuit comprises a feedback voltage comparison portion and a duty ratio adjustment portion. The feedback voltage comparision portion compares a feedback voltage, which is detected from an output end of the switching mode power supply apparatus, and a referece voltage, which is predetermined to be smaller than an overvoltage that is set with respect to the switching mode power supply apparatus, and the duty ratio adjustment portion reduces a switching duty ratio of the switching mode power supply apparatus when the feedback voltage is higher than the reference voltage. By adjusting an on/off switching ratio of a power device in advance when the feedback voltage exceeds the reference voltage that is lower than the overvoltage, instead of suddenly maintaining the switch of the power device to off when the feedback voltage reaches the overvoltage, an output voltage can be prevented in advance from becoming an overvoltage, and system stability can also be enhanced. |
