| 摘要 |
A switching power supply includes a power converter which includes a transformer and a switch, a current sensor, a switch controller and a compensation resistor. The current sensor is operable for generating a current monitoring signal indicating a current through a primary winding of the transformer. The switch controller is operable for receiving a feedback signal indicating an output voltage of the power converter, generating a driving signal based on the feedback signal to control an input power and an output power of the transformer, receiving a line voltage signal indicating an input voltage of the power converter, and generating a compensation current corresponding to a peak value of the line voltage signal. The compensation resistor is coupled between the current sensor and the switch controller. A voltage of the current monitoring signal is inversely proportional to the input voltage under control of the compensation current and the compensation resistor. |
| 主权项 |
1. A switching power supply comprising:
a power converter comprising a transformer and a switch controlled by a driving signal, said transformer comprising a primary winding operable for receiving an input power from an AC/DC (alternating current/direct current) converter and a secondary winding operable for providing an output power for a load; a current sensor, coupled between said switch and ground, operable for generating a current monitoring signal indicating a current through said primary winding; a switch controller, coupled between an optical-coupler and said primary winding, operable for receiving a feedback signal from said optical-coupler, generating said driving signal based on said feedback signal to control said input power and said output power, receiving a line voltage signal indicating an input voltage of said power converter, and generating a compensation current corresponding to a peak value of said line voltage signal, wherein said feedback signal indicates an output voltage of said power converter, and wherein said AC/DC converter is operable for converting an AC voltage to said input voltage and providing said input voltage to said power converter; and a compensation resistor coupled between said current sensor and said switch controller, wherein a voltage of said current monitoring signal is inversely proportional to said input voltage under control of said compensation current and said compensation resistor, wherein said voltage of said current monitoring signal increases if said input voltage decreases, and wherein said voltage of said current monitoring signal decreases if said input voltage increases. |
