The IL410 and IL4108 consist of GaAs IRLED photocoupled to a photosensitive zero-cross thyristor network. The thyristor consists of two monolithic thyristors in parallel in reverse. The three semiconductors are assembled in a six-pin, dual-in-line package. High input sensitivity is achieved through the use of emitter follower phototransistors and cascaded thyristor predrivers, resulting in LED trigger currents of less than 2 mA (DC). Static dV/dt greater than 10 kV/ms can be achieved using dedicated dV/dt pliers.
The clamp circuit has a MOSFET that is enhanced when high dV/dt peaks occur between MT1 and MT2 of the thyristor. When conducting electricity, the FET clamps on the base of the phototransistor, disabling the first stage thyristor predriver. The zero cross line voltage detection circuit consists of two enhanced MOSFETs and a photodiode.
The suppression voltage of the network is determined by the enhancement voltage of the N-channel fET. P-channel FETs are enabled by a photocurrent source that allows the FETs to direct the main voltage to the gate on the n-channel FETs. Once the main voltage can make the n channel, it clamps on the base of the phototransistor, disabling the first stage thyristor predrive. 600 V, 800 V blocking voltages allow off-line voltage control up to 240 VAC, safety factor over 2, and sufficient to reach 380 VAC.
The IL410, IL4108 separate low-voltage logic from 120 VAC, 240 VAC and 380 VAC lines to control resistive, inductive or capacitive loads, including motors, solenoids, high-current thyristors or thyristors and relays.
