The onsemi 4N35S is a single-channel optoisolator from the 4N3X series, housed in a 6-SMD Gull Wing package (supplier device package 6-SMD) and delivered in tube format. It accepts a DC input and provides a transistor-with-base output, making it suitable for isolating logic-level signals across a galvanic barrier. Rated for 5300 Vrms isolation, the part meets the creepage and clearance requirements for reinforced insulation in mains-connected equipment — a common spec for industrial PSU feedback loops, PLC digital inputs, and motor-drive interface circuits. Minimum current transfer ratio is 100% at 10 mA forward current, with typical turn-on and turn-off times of 2 µs each. That switching speed is adequate for 100 kHz-class data rates but not for high-speed digital buses — the part is best suited for status feedback, relay drivers, and slow serial links where isolation integrity matters more than edge rate.
Temperature range and output limits
Operating temperature spans -55°C to 100°C, covering industrial and some military-grade environments — the lower bound suits outdoor telecom cabinets in cold climates, while the upper limit keeps the opto functional in enclosed power supplies without active cooling. Maximum output voltage is 30 V, and Vce saturation is 300 mV max — the low saturation voltage means the output transistor can drive a 5 V logic input directly without a level-shift stage, as long as the collector current stays within the device's limits. Forward current is rated to 100 mA DC max, with a typical forward voltage of 1.18 V. The input LED's current-limiting resistor should be sized to keep If at 10–20 mA for the specified CTR — driving it near the 100 mA absolute maximum reduces reliability and raises the LED junction temperature.
Lifecycle and compliance
onsemi lists the 4N35S as Obsolete. ROHS3 compliant, so it meets current EU restriction requirements for new builds that accept obsolete inventory. For a BOM line that requires this exact isolation rating and package, the procurement path is a spot-market search against the 4N35S order code. Availability and pricing are lot-specific and confirmed at RFQ — no stock-holding claim is made here.