5000Vrms isolation — the rating that defines the application
The Vishay VO615A-4 is a single-channel optocoupler with a transistor output, designed for galvanic isolation up to 5000Vrms. That isolation voltage is the headline spec: it tells you this part is built for industrial power supplies, motor-drive feedback paths, PLC digital inputs, and medical equipment where the safety barrier must hold off several kilovolts between primary and secondary sides. The 4-DIP through-hole package (0.300" lead spacing) is the standard footprint for these applications — no reflow profile needed, hand-solder or wave-solder friendly.
The current transfer ratio is specified at 160% minimum and 320% maximum, both measured at 10 mA forward current.
Output voltage and current — where it drives
The output transistor is rated for 70V collector-emitter and 50 mA continuous current per channel. That 70V ceiling covers 24V industrial rails with healthy margin, and the 50mA drive handles a standard 5V relay coil or a 24V PLC input opto-isolator load. Vce saturation is clamped at 300mV max, so the voltage drop across the output when fully on stays low — important for maintaining rail voltage to the downstream logic.
Rise time is 3 µs typical, fall time 4.7 µs typical, turn-on time 6 µs typical, turn-off time 5 µs typical.
No last-time-buy notice, no end-of-life risk — this part is still in Vishay's current production portfolio.