The onsemi CNY17F1SD is a single-channel optoisolator with a DC input LED and a phototransistor output, rated for 5300Vrms isolation between primary and secondary sides. Current transfer ratio (CTR) is specified at 40% minimum and 80% maximum, measured at a forward current of 10mA — this bin ensures consistent gain across the production band, so a design that works at the min CTR will hold up across the full reel. Switching speed is characterised by a 1µs typical rise time and 2µs fall time; turn-on and turn-off times are 2µs and 3µs typical respectively, placing it in the medium-speed class for optoisolators.
Housed in a 6-SMD Gull Wing package (supplier device package 6-SMD), the part is intended for surface-mount assembly and is supplied on Tape & Reel for automated pick-and-place. The Gull Wing leads provide a low-profile solder joint with visible inspection access — useful for rework or manual touch-up on a repair bench where the scorch mark tells you which part died.
Operating limits and temperature grade
Rated for an ambient operating range of -55°C to 100°C, the CNY17F1SD covers industrial and some military-temperature applications without derating the isolation voltage. Maximum continuous forward current is 100 mA, and the output transistor can sink up to 50 mA per channel at a maximum collector-emitter voltage of 70V — the 300mV Vce(sat) ceiling keeps the output drop low enough to drive a logic input or a small relay coil directly. Typical forward voltage at rated current is 1.35V, which is standard for an IR LED in this isolation class.
For a board that came across the bench with a dead optoisolator, the replacement path is through independent surplus or broker channels.