5000Vrms isolation for industrial and power applications
The FOD817S from onsemi is a single-channel optoisolator with a DC input and transistor output, rated for 5000Vrms isolation. That isolation level suits it for breaking ground loops in motor drives, PLC digital inputs, and switch-mode power supply feedback paths where safety isolation is required. The 4-SMD gull-wing package is a surface-mount variant of the common FOD817 through-hole family, letting you drop it onto a reflow assembly without a hand-loading step.
CTR and switching speed for signal integrity
Current transfer ratio spans 50% to 600% at a forward current of 5mA. This wide spread means you design the pull-up resistor and threshold for the minimum CTR; the upper end just gives you extra margin on output saturation. Maximum Vce saturation is 200mV, which keeps the output voltage drop low when the transistor is fully on, important for logic-level compatibility with 3.3V or 5V systems.