5000Vrms isolation in a 4-DIP through-hole package
The FOD817C300W is a single-channel optoisolator from onsemi with a DC input and a phototransistor output. Its 5000Vrms isolation voltage suits it for safety-barrier applications in power supplies, motor drives, and PLC digital input modules where galvanic isolation is required between the low-voltage control side and the high-voltage field side. The current transfer ratio spans 200% minimum to 400% maximum at a forward current of 5 mA. This CTR window means the output transistor can sink enough collector current to drive a logic input or a relay coil without needing an external gain stage, as long as the load stays within the 50 mA continuous output rating and 70 V collector-emitter voltage.
Switching speed and saturation voltage
For a 24 VDC PLC input with a 3 ms hardware debounce, these edges are fast enough — but if you're driving a high-speed counter or encoder input, the 4 µs rise time limits the maximum detectable frequency to roughly 125 kHz before the output pulse width collapses. Maximum Vce saturation is 200 mV at the rated output current. That low saturation voltage keeps the power dissipation in the output transistor low, which matters when the ambient temperature climbs toward the 110°C upper limit.
The part is ROHS3 compliant. Supplied in a Tube of the standard 4-DIP (0.400", 10.16 mm) through-hole package. The through-hole body is a familiar footprint for rework — no hot-air profile needed, just a soldering iron and a desoldering pump.