Isolation and output rating for industrial loads
The FOD852 is a single-channel Darlington-output optoisolator rated for 5000Vrms isolation. The Darlington pair gives a current transfer ratio of 1000% minimum to 15000% maximum at 1 mA forward current — meaning the output can sink orders of magnitude more current than the LED drives, so a low-power logic pin on one side can switch a 150 mA load on the other. Output transistor collector-emitter breakdown is rated to 300V. That covers rectified 240VAC rails and 300VDC bus monitoring without an external clamp. The 1.2V typical Vce(sat) at rated output current keeps conduction loss low enough that the 4-DIP package can dissipate the heat without a heatsink in most ambient conditions.
Switching speed and temperature range
Rise time is 100 µs typical, fall time 20 µs typical. That is slow relative to transistor-output optos — the Darlington gain stage adds storage time. For 50/60 Hz line-frequency sensing, relay-coil drive, or DC-level detection the speed is adequate; for high-speed serial isolation or PWM above a few hundred Hz, a faster phototransistor or digital isolator would be needed. Operating temperature range is -30°C to 100°C. The upper limit covers the inside of a panel near transformers or drives.
Package and lifecycle status
The 4-DIP (0.300", 7.62mm) through-hole package is a standard footprint shared with many 4-pin DIP optos — the supplier device package is 4-DIP. The part is ROHS3 compliant.