Simple TRIAC dimmable LED driving solution free of large passive input filter, DC bus capacitor or bleeding resistor

A simple solution for TRIAC dimmable LED drivers free of using large passive input filters, DC bus capacitors or bleeding resistors is proposed. Under the proposed method, the LED driver is constantly shorted at the input when the TRIAC is off and automatically turned to the switching state, and regains large input impedance right after the TRIAC is turned on. Experimental results showing the working waveform of the LED driver under dim are reported.