What the 7500Vpk isolation means for your BOM
The 4N26FM provides 7500Vpk galvanic isolation between the input LED and the output phototransistor — that is a high-voltage barrier for a 6-pin SMD package, suitable for isolating control logic from a noisy power stage or a high-side sensor. With a minimum current transfer ratio of 20% at 10 mA forward current, the output transistor can sink enough current to drive a logic gate or a small relay coil without an extra gain stage. Switching is rated at 2 µs turn-on and 2 µs turn-off typical — fast enough for 100 kHz data rates or PWM feedback loops, but not for high-speed digital isolation above a few megahertz.
Package and temperature grade
Housed in a 6-SMD Gull Wing package (supplier device package 6-SMD), the 4N26FM is hand-solderable with a fine-tip iron — no hot-air rework needed, which is a plus for prototyping or small-batch assembly. Rated for -55°C to 100°C operating temperature, it covers industrial and some automotive under-hood environments where the ambient stays below the 100°C ceiling.
Lifecycle reality — obsolete, but sourced
Available through independent distribution channels; quantities are lot-specific and confirmed at RFQ. No pin-compatible drop-in replacement from onsemi is documented, so a BOM change or board spin may be required for new designs.