The IL421x consists of an AlGaAs IRLED opticallycoupled to a pair of photosensitive non-zero crossingSCR chips and are connected inversely parallel toform a TRIAC. These three semiconductors areassembled in a six pin 0.3 inch dual in-line package,using high insulation double molded, over/underleadframe construction.High input sensitivity is achieved by using an emitterfollower phototransistor and a cascaded SCR predriverresulting in an LED trigger current of less than1.3 mA (DC).The IL421x uses two discrete SCRs resulting in acommutating dv/dt of greater than 10 kV/µs. The useof a proprietary dv/dt clamp results in a static dv/dt ofgreater than 10 kV/µs. This clamp circuit has a MOSFETthat is enhanced when high dv/dt spikes occurbetween MT1 and MT2 of the TRIAC. The FET clampsthe base of the phototransistor when conducting, disablingthe internal SCR predriver.The blocking voltage of up to 800 V permits control ofoff-line voltages up to 240 VAC, with a safety factor ofmore than two, and is sufficient for as much as 380VAC. Current handling capability is up to 300 mARMS, continuous at 25°C.The IL421x isolates low-voltage logic from 120, 240,and 380 VAC lines to control resistive inductive, orcapacitive loads including motors solenoids, highcurrent thyristors or TRIAC and relays.Applications include solid-state relays, industrial controls,office equipment, and consumer appliances.
