Isolation barrier and CTR for PSU feedback and PLC I/O
The FOD2741AV is a single-channel optoisolator from onsemi with a guaranteed 5000 Vrms isolation rating — that barrier is the primary safety isolation in a switch-mode power-supply feedback loop or a 24 V PLC digital input module. Current transfer ratio is specified as 100% minimum and 200% maximum at a forward current of 10 mA. The 200% ceiling prevents the output from saturating too hard at low load, which can slow turn-off in high-speed switching.
Package, temperature grade, and output ratings
Housed in an 8-DIP (0.300-inch, 7.62 mm) through-hole package, the FOD2741AV is a drop-in for existing DIP-8 optocoupler footprints. Output voltage is rated to 30 V max and output current to 50 mA per channel. For a typical 24 V PLC input, the 30 V ceiling leaves 6 V of headroom — adequate for most field-side signals, but check the transient rating if the line sees inductive kickback.
The base product number is FOD2741; the 'V' suffix indicates the specific CTR bin and package variant. For volume builds, confirm the tube quantity with your distributor — tube counts vary by manufacturer and affect pick-and-place feeder setup if you hand-load DIPs.