The ILQ620-X009 is a quad-channel optocoupler from Vishay that packs four transistor-output channels into a single 16-SMD gull-wing package. The AC/DC input type means the LED side accepts both polarities — handy when you're sensing AC mains crossover or bidirectional logic levels without an external bridge rectifier.
CTR range and drive current — sizing the input side
Current transfer ratio spans 50% to 600% at a 5mA forward current. That wide spread means you size the input resistor for the minimum CTR to guarantee the output saturates at the load current, then let the higher-CTR units simply saturate harder. The 1.15V typical forward voltage is standard for an IR LED, so a 5V logic rail with a 680Ω series resistor lands right at 5mA. Output side: each channel can sink 50mA at up to 70V, with a 400mV max Vce(sat) — enough to drive a 24V PLC input or a small relay coil directly.
Speed and timing — where the 20µs rise time matters
Rise time is 20µs typical, fall time 2µs, with turn-on/turn-off at 3µs and 2.3µs respectively. This part isn't for high-speed data — 10 kHz switching is about the practical ceiling. It's built for status feedback, relay drivers, and slow opto-isolated serial links where the 5300Vrms isolation is the priority, not the baud rate.
Rated -55°C to 100°C operating, which covers military avionics bays, outdoor telecom cabinets, and downhole instrumentation. The 16-SMD gull-wing package is reflow-compatible and suits automated assembly, but the wide temp range also means the part survives the thermal cycling of a motor drive enclosure.