5300Vrms isolation — obsolete part, sourced to BOM
The onsemi CNY17F1S is a single-channel transistor-output optoisolator in a 6-SMD Gull Wing package. It provides 5300Vrms galvanic isolation between a DC input LED and a phototransistor output, with a guaranteed current transfer ratio (CTR) of 40% to 80% at a forward current of 10mA. This isolation rating suits applications requiring reinforced insulation per IEC 60950-1 or IEC 62368-1 — think AC mains crossing to low-voltage control logic in power supplies, motor drives, or PLC I/O modules where the safety barrier must hold off transient surges. The part is now classified as Obsolete by onsemi. No direct pin-compatible replacement is listed on the official record.
CTR window and switching timing
The 40–80% CTR range at If=10mA means the phototransistor collector current is guaranteed between 4mA and 8mA when the LED is driven at 10mA — a wide enough band that the downstream logic threshold must be set to trigger reliably at the low end. The 70V Vce(max) and 50mA output current per channel are typical for general-purpose logic-level isolation. Turn-on time is 2µs typical, turn-off 3µs typical, with rise/fall of 1µs/2µs. This limits the part to switching below roughly 100 kHz — adequate for 50/60 Hz mains zero-cross detection, relay drive, or slow digital signals, but not for high-speed data or PWM gate drive. The 1.35V typical forward voltage at 10mA and 100mA absolute-max forward current set the LED drive budget. The -55°C to +100°C operating range covers industrial and some military-grade thermal environments.
Package and board-fit note
The 6-SMD Gull Wing package (supplier device package 6-SMD) has a standard 1.27mm (0.050-inch) lead pitch and a body width of about 6.5mm. The Gull Wing leads are coplanar to within 0.1mm — inspect the solder joint on the first article for heel fillet wetting, as the lead standoff from the board is only 0.25mm typical. Supplied in Tube packaging — 50 units per tube typical for this footprint.