The onsemi CNY172SM is a 1-channel optoisolator with a phototransistor output that includes a base connection — that base pin lets you bias the transistor for faster switching or lower saturation, or leave it floating for standard transistor operation. Its 4170 Vrms isolation rating means it can safely bridge a 400 VAC power stage and a 5 V logic controller with enough margin for transient overvoltages — common in motor-drive feedback, SMPS secondary sensing, and PLC digital input isolation. The current transfer ratio (CTR) is specified at 63% minimum and 125% maximum when you drive the LED with 10 mA forward current — that 2:1 spread means the output current at the same input can vary by a factor of two across parts, so downstream logic should be a Schmitt trigger or comparator, not a direct TTL gate. Switching is rated at 4 µs rise and 3.5 µs fall (max), with turn-on at 2 µs and turn-off at 3 µs — fast enough for 10 kHz PWM or 115 kbps serial isolation, but not for high-speed isolated SPI or CAN FD.
Package and hand-solder reality
The tube packaging means parts arrive in a rigid anti-static tube, not on a reel — fine for prototyping and low-volume builds, but if your pick-and-place line expects tape-and-reel, you'll need to transfer or order a reeled variant from the same base family.
ROHS3 compliant with no exemptions, meaning fully lead-free and compatible with EU RoHS and global environmental regulations — no waiver paperwork needed.