Active production, surface-mount isolation
The CNY172SVM is an active-production optoisolator from onsemi, rated for 4170Vrms isolation between input and output. That isolation voltage qualifies it for reinforced insulation in mains-connected industrial controls, PLC digital inputs, and motor-drive feedback paths where safety isolation is required. It comes in a 6-SMD Gull Wing package — the surface-mount variant of the through-hole CNY17 family. The Gull Wing leads sit flat on the pad and reduce tombstoning risk during reflow, but check the MSL before you place it; onsemi typically rates these at MSL 1, so no bake needed unless the bag is breached. The transistor-with-base output gives you access to the base node for speed-up networks or Miller clamp — useful when you need to tailor the switching response.
CTR range and switching timing
Current transfer ratio is specified at 63% minimum and 125% maximum at If=10 mA. That 2:1 spread is typical for phototransistor optos and means the LED drive current must be sized for the low end to guarantee saturation across temperature and device aging. Turn-on time is 2 µs typical, turn-off 3 µs typical; rise and fall times are 4 µs and 3.5 µs max. These are adequate for 10–100 kHz switching in IGBT gate drive or AC mains zero-cross detection, but not for high-speed serial isolation — the phototransistor output limits bandwidth to roughly 100 kHz. The output can handle up to 70 V collector-emitter and 50 mA continuous current. The 400 mV max Vce(sat) at the rated current keeps conduction loss low enough that the 6-SMD package can dissipate the heat without a heatsink.