Patent ID: 7330361

Claim:
A capacitor charging module for maintaining a pre-determined voltage level on an output capacitor, comprising: a power switch; a power delivery device controlled by the power switch, for providing a charging current to the output capacitor according to a voltage source; a voltage divider for providing a feedback voltage according to the voltage on the output capacitor; a control circuit coupled to the voltage divider and the power switch, for controlling on/off operation of the power switch according to the feedback voltage value, wherein the control circuit turns off the power switch when the voltage level on the output capacitor is at or above the pre-determined value; a first rectifier component, coupled between the voltage divider and the power delivery device, for preventing the feedback voltage being a negative voltage during on periods of the power switch; and a second rectifier component, having a first end coupled to the output capacitor and having a second end coupled to the first rectifier component and the voltage divider, for preventing an reverse current flowing from the output capacitor to the power delivery device.