Triacs are bidirectional ac switches that can control loads with currents as high as 25A rms at voltages as high as 600V. They find wide use in motor-speed, heater, and incandescent-lamp controls.

Check out this link for On Semiconductor’s datasheet for a line of “Zero-Cross Optocoupled Triac Drivers.” The ability to zero-cross when turning on AC line voltage to some loads may be advantageous.

The LM3445 from National Semiconductor enables a full 100:1 range of offline, uniform, flicker-free dimming for high-brightness LEDs with a conventional TRIAC forward or reverse phase-control wall ...

Triacs are used to control ac mains loads in home appliances, and commercial and industrial equipment. In the majority of applications, the triac will dissipate sufficient power to make thermal ...