Isolation and signal transfer for safety-rated designs
The FOD817B3S is a single-channel optoisolator from onsemi's FOD817 family, designed to pass a DC-level logic signal across a 5000Vrms isolation barrier while the output transistor switches up to 70V at 50mA. With a current transfer ratio guaranteed between 130% and 260% at a 5mA forward current, the part provides a predictable gain window for driving downstream logic or a microcontroller input without extra amplification.
Temperature grade and environment fit
The 4-SMD Gull Wing package allows reflow soldering and a lower profile than the through-hole FOD817B, but the 200mV Vce saturation means the output drop is tight enough to keep the logic-high level above 3.3V or 5V thresholds even at 50mA load.
onsemi lists the FOD817B3S as Active and ROHS3 compliant, so no near-term end-of-life watch is needed for new designs.