Isolation voltage and CTR — the two numbers that decide the fit
The onsemi CNY174SR2VM is a single-channel DC-input optoisolator with a transistor-with-base output, rated for 4170Vrms isolation between input and output. That isolation voltage qualifies it for reinforced insulation in mains-connected circuits per IEC 60950-1 — the 4170Vrms test voltage corresponds to a working voltage of several hundred volts with a safety margin for transient overvoltages. This CTR band means the output transistor saturates with at least 16mA collector current for every 10mA input — enough headroom to drive a standard TTL or CMOS logic input without additional gain stages, but the 320% ceiling means the designer must check that the output pull-up resistor does not force the transistor out of saturation at the high end of the CTR range.
Switching speed and output drive — timing budget for logic interfaces
Turn-on time is 2µs typical, turn-off time 3µs typical, with rise and fall times of 4µs and 3.5µs maximum respectively. For a 10kHz data rate these switching edges consume about 4% of the bit period — acceptable for most PLC digital inputs and status feedback loops, but a 100kHz signal would leave less than 2µs of settled time per cycle, so the designer should budget the propagation delay skew across temperature. The output transistor can handle 70V collector-emitter and sink 50mA continuous per channel. This 70V rating covers 24V industrial logic rails with margin for inductive kickback, and the 50mA drive is sufficient for small relays or LED indicators without a buffer transistor.
Package and temperature grade — board integration constraints
Housed in a 6-SMD gull-wing package (supplier device package 6-SMD), the CNY174SR2VM is a surface-mount part with a 1.27mm pin pitch typical for this footprint class. The gull-wing leads provide visual solder-joint inspection access and relieve mechanical stress between the package body and the board during thermal cycling. The 100°C upper limit is below the 125°C automotive grade, so it is suited for factory-floor control cabinets and HVAC equipment but not for under-hood or engine-bay deployment without thermal derating analysis.
Active lifecycle and compliance documentation
The base product number is CNY174, and the SR2VM suffix indicates the tape-and-reel packaging option with a specific lead-finish and packing quantity. As an active part, it is sourced through authorized distribution channels.