7500Vpk isolation — what it means for the BOM
The 4N28FVM: The 7500Vpk isolation rating is the transient overvoltage the optocoupler withstands between input and output — not the continuous working voltage. For reinforced insulation in mains-connected circuits, this peak rating supports applications up to 600Vrms working voltage per IEC 60950-1, but the designer must derate for altitude and pollution degree per the end-equipment standard. With a minimum current transfer ratio of 10% at 10mA forward current, the output transistor saturates with as little as 1mA collector current — enough to drive a logic gate input or a low-power relay coil directly. Turn-on and turn-off times are both 2µs typical, placing the switching ceiling around 250kHz for a 50% duty-cycle signal. This suits isolated data lines, PLC digital inputs, and motor-drive feedback paths where the switching frequency stays below 100kHz.
Supplied in a 6-SMD gull wing package (6-SMD supplier device package), the 4N28FVM mounts on the surface of a PCB with a standard 1.27mm pitch footprint. The gull-wing leads provide visual solder-joint inspection access and relieve mechanical strain between the package body and the board. Rated for operation from -55°C to 100°C ambient, the part covers industrial temperature range — suitable for outdoor telecom cabinets, factory-floor control panels, and engine-bay electronics where the enclosure sees temperature swings.