3750Vrms barrier in a 4-SOP footprint
The FODM217D is a single-channel optoisolator from onsemi's FODM217 series, delivering 3750Vrms isolation between a DC-input LED and a phototransistor output. The 4-SOP package (4.40mm width) fits designs where board space is tight but reinforced isolation is required — common in industrial I/O modules, PLC interfaces, and isolated sensor feedback paths. With a minimum current transfer ratio of 300% at 5mA forward current, the part guarantees the output transistor saturates even when the LED is driven at modest current, which helps keep the input-side power budget low. The 80V output rating covers 24V and 48V bus rails with margin.
The 2µs rise and 3µs fall times (typical) set the practical switching frequency ceiling around 100 kHz — adequate for isolating slow digital signals, relay drivers, or status feedback, but not for high-speed data links. Turn-on and turn-off times are both 3µs typical, meaning the output transition symmetry is close enough for most non-timing-critical isolation gates. The 400mV max Vce(sat) at the output ensures low voltage drop when the transistor is fully on, preserving headroom for the downstream logic input.