7500 Vpk isolation in a 6-SMD gull-wing package
The onsemi 4N28FR2VM is a single-channel optoisolator in a 6-SMD gull-wing package, with a DC input LED and a phototransistor output that brings the base terminal out. The headline figure is the 7500 Vpk isolation voltage — this is the withstand rating between input and output, tested per the device's isolation specification. For a line-voltage interface or a medical-grade barrier where the creepage distance across the board must hold off several kilovolts, this part provides the margin a standard 5000 V isolator cannot.
CTR floor and switching speed — what they mean for the loop
The minimum current transfer ratio is 10 % at a forward current of 10 mA. This means that with 10 mA through the LED, the output transistor can sink at least 1 mA — enough to drive a TTL or CMOS gate input directly, but not enough for a relay coil without a buffer stage. The 2 µs typical turn-on and turn-off times set the upper data rate at roughly 250 kbit/s in a non-return-to-zero scheme; above that the output pulse width narrows until the downstream logic misses edges. The output transistor is rated for 30 V maximum collector-emitter voltage, with a saturation voltage of 500 mV at the rated collector current.
onsemi has marked the 4N28FR2VM as obsolete. The part is sourced through independent distribution channels — quantities are lot-specific and confirmed at RFQ. For a BOM line that already carries this order code, the existing board layout and isolation rating are locked in; a board spin would be required to move to a different package or pinout.
Temperature range and surface-mount integration
Rated for -55 °C to 100 °C operating ambient, the 4N28FR2VM covers the industrial temperature band with margin into the military low end. The 6-SMD gull-wing package (supplier device package 6-SMD) is a standard surface-mount footprint — the gull-wing leads are visible for AOI inspection and reworkable with hot air. The tape-and-reel packaging suits automated pick-and-place assembly.