Package and board-fit — 6-DIP through-hole
The 4N35TM is supplied in a 6-DIP package with 0.400-inch (10.16 mm) body width, through-hole mounting.
Isolation and switching — what the ratings mean
Rated for 7500 Vpk isolation, this optocoupler provides reinforced insulation for separating high-voltage and low-voltage domains in a single package — suitable for motor-drive feedback, SMPS secondary-side sensing, and industrial I/O isolation where transient immunity matters. Minimum current transfer ratio of 100% at 10 mA forward current means the output transistor can sink at least as much collector current as the LED draws — a 1:1 floor that guarantees the logic-level interface works across the full input current range without gain staging. Typical turn-on and turn-off times of 2 µs each set the data-rate ceiling below 250 kbps — fine for 50/60 Hz zero-crossing detection, relay driver feedback, and slow digital isolation, but not for high-speed serial buses.
Temperature grade and environment
Operating range from -40°C to 100°C covers industrial enclosures and outdoor telecom cabinets.
Lifecycle reality — obsolete, sourced to order
onsemi has marked the 4N35TM as obsolete. No pin-compatible direct replacement from onsemi has been announced; a functional equivalent would need to match the 6-DIP footprint, 7500 Vpk isolation, and 100% CTR minimum.