Isolation and signal transfer for industrial boards
The CNY173SM: Its current transfer ratio (CTR) is specified at 100% minimum and 200% maximum when the LED is driven at 10mA — this range tells you the output transistor's collector current relative to the input current, so a 10mA input guarantees at least 10mA of drive at the output side, which is enough to saturate a logic input or a small relay coil without extra gain stages. The output transistor can handle up to 70V across the collector-emitter and sink 50mA continuously, with a saturation voltage of just 400mV at full drive — that keeps the power dissipation low when switching a 5V or 12V PLC input module. Switching is clean: typical turn-on time is 2µs and turn-off is 3µs, with rise and fall times of 4µs and 3.5µs respectively — fast enough for 100kHz-level data or PWM signals without distorting the pulse width.
Package, footprint, and temperature grade
Housed in a 6-SMD gull-wing package (supplier device package 6-SMD), the CNY173SM is designed for surface-mount assembly on a standard PCB footprint — the gull-wing leads are hand-solderable with a fine-tip iron or a hot-air station, and the 1.27mm pitch gives you room to probe or rework without a microscope. It ships in a tube, which is the standard handling format for pick-and-place lines that feed from tube magazines — if your line uses tape-and-reel, check with your distributor about alternate packaging options at quote time.