5000Vrms isolation in a 4-SMD gull-wing
The FOD817DSD is a single-channel optoisolator from onsemi's FOD817 family, delivering 5000Vrms of galvanic isolation between a DC input LED and a phototransistor output. The 4-SMD gull-wing package (4-PDIP-GW footprint) is surface-mount, so it reflows with the board — no hand-soldering required unless you are doing a field swap. The 200mV max Vce saturation means the output transistor will not drop much voltage when on, which matters if you are driving a logic input or a low-current relay coil.
CTR spread and temperature range
Current transfer ratio is specified at 300% min and 600% max at If=5mA. That is a 2:1 spread — if your circuit depends on a tight CTR (e.g., for a precise threshold), you may need to sort by bin or use the FOD817A variant with a narrower range.
Active production, no end-of-life watch
The base product number FOD817 has a long production history, so supply continuity is reasonable. We source it per RFQ — confirm your quantity and we will quote current pricing and lead time.