Isolation and signal transfer — what 5000Vrms and 100-200% CTR mean for the BOM
The FOD2741BSV is a single-channel transistor-output optocoupler from onsemi, providing 5000Vrms of galvanic isolation between the DC input and the output transistor side. The current transfer ratio (CTR) is specified as 100% minimum and 200% maximum at a forward current of 10 mA. This means the output transistor can sink at least as much collector current as the LED is drawing — a 10 mA LED drive yields at least 10 mA at the output, with headroom up to 20 mA. The tight CTR binning (2:1 max spread) simplifies worst-case logic-level design across temperature and LED aging.
Output ratings and saturation — driving the load side
The output transistor is rated for 30 V maximum collector-emitter voltage and can sink up to 50 mA continuous per channel. With a Vce saturation of 400 mV max at the rated current, the voltage drop across the optocoupler stays low enough to drive a 5 V logic input or a small relay coil without an extra buffer stage. The 8-SMD Gull Wing package (also listed as supplier device package 8-SMD) suits reflow assembly on standard FR-4 boards.
The base product number is FOD2741, and the part ships in bulk packaging. For compliance documentation (RoHS, REACH, UL recognition), refer to the onsemi product page or request the certificate of compliance with your order.