IL4218 (VISHAY)

The IL4218 is a 6-pin Phototriac Output Optocoupler consists of an AlGaAs IRLED optically coupled to a pair of photosensitive non-zero crossing SCR chips and is connected inversely parallel to form a TRIAC. High input sensitivity is achieved by using an emitter follower phototransistor and a cascaded SCR predriver resulting in an LED trigger current of less than 1.3mA (DC). The use of a proprietary dV/dt clamp results in a static dV/dt of greater than 10kV/µs. This clamp circuit has a MOSFET that is enhanced when high dV/dt spikes occur between MT1 and MT2 of the TRIAC. The FET clamps the base of the phototransistor when conducting, disabling the internal SCR predriver. The blocking voltage of up to 800V permits control of off-line voltages up to 240VAC, with a safety factor more than two and is sufficient for as much as 380VAC. Current handling capability is up to 300mA RMS, continuous at 25°C.