The FOD817C is a single-channel optocoupler from onsemi, built with a DC-input LED and a phototransistor output in a 4-DIP through-hole package. It provides 5000Vrms of galvanic isolation between input and output sides. Current transfer ratio (CTR) is specified at 200% minimum and 400% maximum when the LED is driven at 5mA forward current. That 2:1 spread is tight for a phototransistor coupler — it keeps the logic threshold predictable across temperature and lot without a secondary gain stage. The output transistor can handle up to 70V collector-emitter and 50mA continuous current, with a typical Vce(sat) of 200mV at rated load. Rise and fall times are 4µs and 3µs typical, which puts the usable switching frequency around 100 kHz for digital isolation or slow-edge analog coupling.
Temperature range and isolation rating
Operating temperature spans -55°C to 110°C, which covers industrial control cabinets and outdoor telecom enclosures without derating. The 5000Vrms isolation rating meets basic reinforced insulation requirements per IEC 60950-1 for mains-separated circuits. The 4-DIP package (0.300-inch body width, 7.62mm lead spacing) is a standard footprint that drops into existing PCB layouts for the FOD817 series. The tube packaging means it ships in anti-static tubes for pick-and-place or hand assembly.
The base product number FOD817 covers a family of CTR-binned variants — the 'C' suffix selects the 200-400% CTR window. If your design calls for a tighter or wider CTR range, the FOD817A (80-160%) or FOD817B (130-260%) are the same footprint and pinout.