3750Vrms isolation with AC/DC input flexibility
The onsemi FODM2705R2 is a 1-channel transistor-output optocoupler rated for 3750Vrms isolation — sufficient for reinforced insulation in mains-connected circuits under IEC 60950-1 and IEC 62368-1. The AC/DC input stage means a single BOM line covers both line-frequency AC control signals and DC logic-level drives, reducing inventory complexity.
CTR margin from 50% to 300% at 5mA forward current
Current transfer ratio spans 50% minimum to 300% maximum at If=5mA — a 6:1 spread that gives the designer headroom for LED degradation over temperature and lifetime. At the minimum CTR, 5mA input yields at least 2.5mA at the phototransistor collector, enough to saturate a downstream logic gate or drive a 5V relay coil through the 80mA rated output. Rise and fall times are both 3µs typical, supporting switching frequencies into the low hundreds of kilohertz — adequate for isolated serial interfaces, IGBT gate drive feedback, and AC mains zero-cross detection circuits.
Industrial temperature range and output drive
Operating from -40°C to 110°C, the part covers industrial enclosures, outdoor telecom cabinets, and under-hood automotive environments without derating. The 80mA output per channel with a 40V collector-emitter maximum can sink small relays, solenoids, or PLC input modules directly — eliminating a buffer transistor in many designs.