4170 Vrms isolation, 160–320% CTR, through-hole 6-DIP
The onsemi CNY174VM is a single-channel phototransistor optocoupler in a 6-DIP through-hole package. It provides 4170 Vrms galvanic isolation between a DC LED input and a phototransistor output with base access — a common choice for logic-level signal isolation in industrial control, PLC digital inputs, and serial communication interfaces where the 6-DIP footprint allows manual assembly or rework.
CTR and output ratings — what drives the BOM fit
That spread means the output transistor saturates at a collector current between 16 mA and 32 mA for a 10 mA input — wide enough that the downstream logic threshold must tolerate the full range without redesigning the pull-up resistor. The output transistor is rated for 70 V collector-emitter and 50 mA continuous current, so it can drive a 5 V or 24 V logic input directly through a series resistor.
Switching speed and temperature range
Turn-on time is 2 µs typical, turn-off 3 µs typical; rise and fall times are 4 µs and 3.5 µs maximum respectively. This limits the usable data rate to roughly 100 kbps in a saturated-switching application — fine for 10 kHz PWM feedback or slow serial buses but not for high-speed isolation.
The CNY174VM is listed as Active by onsemi.