| 摘要 |
An LED lighting system is provided. The LED lighting system includes a main transformer, a voltage detector, a current controller, a second reference voltage supplier, and a power factor compensation circuit. The main transformer transforms an input signal to supply the transformed input signal to an LED group. The voltage detector supplies a control voltage proportional to a level of an input voltage corresponding to the input signal. The current controller includes a first voltage storage, a negative voltage applier, a second voltage storage, switch, and a current control signal generator. The first voltage storage stores the control voltage supplied from the voltage detector or discharges a stored voltage. The negative voltage applier is connected to the first voltage storage, and connected to a ground to apply the control voltage to the ground when the control voltage is a negative voltage. The second voltage storage is connected to the first voltage storage, and stores the control voltage applied through the first voltage storage or discharges a stored voltage. The switch is connected to the second voltage storage, and activated by a driving signal to apply a ground voltage to the second voltage storage. The current control signal generator generates a current control signal according to a voltage signal and gain of the second voltage storage. The first voltage storage or the second voltage storage supplies the current control signal through the voltage detector. The second reference voltage supplier supplies the second reference voltage when the control signal supplied from the voltage detector is equal to or greater than the second reference voltage. The power factor compensation circuit controls a duty ratio of the driving signal according to a level of the current control signal, and controls a peak value of a primary current in the main transformer according to a level of the second reference voltage. |
