The 4N26FR2VM is classified as Obsolete by onsemi.
7500Vpk isolation — what it means for the BOM
The 7500Vpk isolation voltage is the peak transient the optocoupler withstands between input and output — this is a reinforced-insulation rating suitable for medical equipment, industrial motor drives, and power-supply feedback loops where galvanic isolation must survive mains transients without breakdown. Minimum current transfer ratio is 20% at 10 mA forward current — the output transistor saturates with 2 mA base drive from a 10 mA LED input, which sets the minimum load current the receiver side can sink while keeping Vce below 500 mV. Switching times are 2 µs typical for both turn-on and turn-off — this limits the data rate to roughly 250 kbps in a saturated-switching application, adequate for 50/60 Hz zero-crossing detection, relay driver isolation, and slow digital status feedback.
Package and temperature grade
Housed in a 6-SMD gull wing package (6-SMD case code), the 4N26FR2VM is intended for surface-mount assembly. The gull-wing leads provide visual solder-joint inspection access and moderate thermal stress relief between the package body and the PCB. Rated for -55°C to 100°C operating temperature — the full military temperature range. This qualifies the part for avionics, satellite, and downhole instrumentation where the ambient spans the -55°C cold soak to 100°C hot-end junction limit.