Isolation and signal-transfer profile
The CNY173300W is a single-channel phototransistor optocoupler from onsemi, delivering 5300Vrms galvanic isolation between a DC input LED and a transistor output with a base terminal — the base pin allows the designer to bias the phototransistor for faster switching or to configure a Darlington pair externally. Switching is rated with a 1µs rise and 2µs fall time typical, and turn-on/turn-off times of 2µs and 3µs respectively — these numbers place it in the medium-speed class for isolated data or status feedback where sub-microsecond edges are not required.
Output ratings and operating envelope
The output transistor is rated for 70V collector-emitter maximum and 50mA continuous current per channel, with a saturation voltage of 300mV at rated current — the low Vce(sat) keeps power dissipation in the output stage manageable when driving a logic input or a relay coil. Operating temperature spans -55°C to 100°C, covering industrial and military-temperature applications — the 100°C upper limit is the junction temperature, so derating the forward current and output current is necessary when the ambient approaches that ceiling.
Housed in a 6-pin DIP with 0.400-inch (10.16mm) body width, through-hole mounting — the wide body provides 5300Vrms creepage distance between input and output pins, a requirement for reinforced insulation in mains-isolated circuits.