A dimmable LED light bulb is an integrated LED lamp with internal dimming circuitry that allows the LED bulb to respond correctly to a phase-control dimmer. Although the use of smart light bulbs allows people to exercise dimming control over their lighting all from the convenience of a smartphone, tablet or voice-controlled speaker, manual dimming with a wall-mount or fixture-integrated dimmer to control a lamp-based lighting system stays in demand.
In residential settings, most mains dimmers are TRIAC-based. These two-wire forward phase controls work smoothly with resistive loads such as incandescent lamps. Resistive light sources draw electricity directly from the AC grid with a sinusoidal load current in phase with the input voltage. A change in the voltage affects the current, and consequently the light output proportionally. LED light bulbs, on the other hand, draw current from a switching mode LED driver which is typically a capacitive circuit. Switching mode LED drivers draw current from the mains in bursts every cycle (repetitive peak currents) when charging their internal capacitors. The power drawn by a switching circuit typically has a non-linear relationship with the RMS value of its input voltage waveform. Repetitive peak currents drawn by capacitive loads can be 5-10 times higher than their RMS current draw.
at the Open Lighting Product Directory (OLPD)
