Design and Implementation of Active Bleeder for TRIAC Dimmable LED Driver

In this paper, the analysis and implementation of active bleeder for TRIAC dimmable LED driver is presented. The insufficient holding current problem occurs when LED driver is connected to TRIAC dimmer, causing TRIAC dimmer misfire and LED flicker. Therefore, a bleeder circuit is parallel-connected to provide TRIAC enough holding current. In the bleeder, the resistor is usually used to control the amount of current through the bleeder, and cause high power loss on the resistor. A bleeder circuit with an inductor, a capacitor and switches is used to provide TRIAC dimmer extra current to reduce the power dissipation by using a resistor. Finally, the hardware type of the bleeder circuit with input voltage of 90~135V is implemented, and able to applied on the TRIAC dimmable 7.2W LED driver. The bleeder can provide enough holding current, widening the conducting angle of TRIAC dimmer with no flicker and misfire occur.