Device identity and isolation rating
The CNY171W: It provides 5300 Vrms galvanic isolation between the DC input LED and the phototransistor output — this is the reinforced isolation class needed for safety barriers in medical, industrial, and power-supply feedback paths where the primary-secondary separation must hold off transient overvoltages.
Output performance and temperature envelope
The output transistor with base access is rated for 70 V collector-emitter and 50 mA continuous current. Current transfer ratio (CTR) is specified at 40% minimum to 80% maximum at If=10 mA — this band is typical for general-purpose logic-level coupling; the 300 mV max Vce(sat) at the rated forward current keeps the output drop low enough to drive TTL or CMOS inputs without a pull-up resistor. Switching is moderate: 1 µs rise, 2 µs fall typ, with turn-on/turn-off times of 2 µs and 3 µs respectively. The 100 mA absolute-maximum forward current on the input LED gives headroom for pulsed drive schemes in noisy backplanes.