Isolation barrier for industrial signal paths
The SFH617A-2X019 is a single-channel transistor-output optocoupler from Vishay's SFH617A series, rated for 5300Vrms isolation between input and output — a common requirement for breaking ground loops in PLC digital inputs, motor-drive feedback, and AC-mains monitoring circuits. The DC input drives an IR LED; the phototransistor output can switch up to 70V at 50 mA continuous, which is enough to drive a 24V PLC input module or a downstream logic gate without a buffer transistor.
CTR range and logic compatibility
Current transfer ratio is specified at 63% minimum and 125% maximum, both measured at If=10 mA. At the minimum CTR, 10 mA input yields about 6.3 mA output current — enough to pull a 5V logic input low through a 4.7 kΩ pull-up resistor. For 3.3V logic, the same CTR margin holds with a 2.2 kΩ pull-up, so no extra gain stage is needed. Typical turn-on time is 3 µs, turn-off 2.3 µs, with rise and fall both at 2 µs. This switching speed supports PWM frequencies up to roughly 100 kHz without significant pulse-width distortion, which matters for encoder feedback or serial data isolation.
Vishay lists the SFH617A-2X019 as Active and ROHS3 compliant. The SMD footprint matches standard 4-pin optocoupler land patterns; the gull-wing leads allow visual solder-joint inspection after reflow.
Temperature range for outdoor and industrial enclosures
The 400mV maximum Vce saturation at the output side keeps conduction loss low across the full temperature range. Forward voltage is 1.35V typical at 10 mA, and the LED can handle up to 60 mA continuous DC forward current — useful if the driving side has a higher current source and you need to drop it with a series resistor.