4170Vrms isolation with transistor base output
The CNY174SR2M is a single-channel optoisolator from onsemi that provides 4170Vrms of galvanic isolation between a DC input LED and a phototransistor output with a base connection. The base terminal gives the designer flexibility to bias the transistor for faster switching or to add external base-emitter resistance for noise immunity — a feature not available on standard phototransistor couplers.
CTR window and switching speed for BOM-fit
The current transfer ratio is guaranteed between 160% and 320% at a forward current of 10 mA. The typical turn-on time is 2 µs and turn-off time is 3 µs, with rise/fall times of 4 µs and 3.5 µs respectively — fast enough for 100 kHz digital isolation or slow serial interfaces like I²C.
Sourcing and compliance posture
onsemi lists the CNY174SR2M as Active in production.
Package and environmental fit
Housed in a 6-SMD gull wing package, the part is designed for surface-mount reflow soldering. The maximum output voltage is 70 V, and the continuous output current per channel is 50 mA — adequate for driving optocoupled feedback in power supplies or isolated I/O modules.