Package and mounting
The ILQ74-X009 is a 4-channel phototransistor optocoupler from Vishay, packing four isolated transistor-output channels into a single 16-SMD gull-wing package. The headline number is the 5300 Vrms isolation rating — that is the voltage the part can withstand between input and output sides, making it a solid choice for industrial PLCs, motor-drive feedback, and any board where you need to cross a safety barrier without a separate isolator per channel. Each channel gives you a phototransistor on the output side, driven by an infrared LED on the input side, with a minimum current transfer ratio of 12.5% at 16 mA forward current. That CTR floor means you need to budget at least 16 mA LED drive to guarantee the output transistor saturates; it is not a low-power part, but it is predictable.
Switching speed and what it limits
Typical turn-on and turn-off times are both 3 µs. That puts the ILQ74-X009 in the slow-to-moderate speed class — fine for reading a 24 V PLC input, detecting a relay closure, or isolating a slow serial signal up to maybe 100 kbps. It will not work for CAN, RS-485 at high baud, or any high-speed data isolation. The output transistor is rated for 20 V maximum on the collector, so keep your pull-up rail at 20 V or less.
Temperature range and field reality
Rated for -55°C to 100°C operating temperature. The 100°C ceiling is the junction temperature limit — if your board sits near a hot power supply or motor drive, derate the LED current above 85°C or you will lose CTR margin. Storage temperature is wider, but operating is the number that matters for the BOM.
Package and mounting — what to expect on the board
Comes in a 16-SMD gull-wing package (16-SMD case style). Surface-mount only — no through-hole version in this order code. The gull-wing leads are visible and inspectable after reflow, which is a plus for field repair; you can touch up a joint with a fine iron if needed. No exposed pad, so thermal management is through the leads and board copper.