The CNY17F2S is a single-channel transistor-output optocoupler from onsemi, part of the CNY17 family. Its 5300Vrms isolation rating qualifies it for reinforced insulation in mains-referenced circuits — enough to separate a 240 VAC field sensor from a 24 VDC PLC backplane without a separate isolation barrier. The current transfer ratio (CTR) is specified as 63% minimum to 125% maximum at If=10mA. That 2:1 spread means the downstream logic input must trigger reliably at the low end of the CTR range — a PLC input drawing 2 mA from the phototransistor needs at least 3.2 mA of LED drive to guarantee turn-on, leaving margin for LED ageing. Turn-on time is 2µs typical, turn-off 3µs typical, with rise/fall of 1µs and 2µs. These numbers set the practical pulse-width limit: a 10 µs input pulse is captured cleanly, but a 5 µs glitch may not reach the output threshold — the device acts as a crude noise filter for short transients on the field side.
Obsolete — the sourcing reality for this optocoupler
onsemi lists the CNY17F2S as Obsolete. The 6-SMD Gull Wing footprint is shared across the CNY17 family, but CTR binning (63-125% for the F2 suffix) is not pin-compatible with an un-binned replacement — a board spin is not required, but the logic threshold may need re-verification if substituting a different CTR grade.
Temperature range and package — board-fit for industrial environments
Rated for -55°C to 100°C operating ambient, the CNY17F2S covers the full industrial temperature band — outdoor PLC cabinets, motor-drive junction boxes, and engine-bay-adjacent control modules all stay within this envelope. The 70V maximum output voltage and 50mA output current are sufficient for driving a 24V PLC input through a series resistor, with the 300mV Vce(sat) ensuring the logic-low threshold is met even at the cold end of the range. The 6-SMD Gull Wing package (supplier device package 6-SMD) is a standard surface-mount footprint for automated pick-and-place. No through-hole variant — the board must support reflow or wave-solder on the gull-wing leads.