| 摘要 |
An LED driving circuit includes a rectifying unit connected to an AC power, an LED unit, a voltage-controlled transistor, a current detection unit, a low-pass filter and a current control unit. The rectifying unit, the LED unit, the voltage-controlled transistor and the current detection unit are connected in series to form a current loop. The current detection unit generates a square DC voltage signal representing the current flow in the current loop. The low-pass filter transfers the square DC voltage signal to an average voltage signal. The current control unit compares the average voltage signal to a reference voltage. According to the result of the comparing, the current control unit outputs a corresponding control signal to the voltage-controlled transistor to maintain the current flow in the current loop as a constant. Therefore, the brightness of the LED unit can be uniform. |
