4170Vrms isolation in a through-hole DIP
The onsemi CNY171VM is a single-channel phototransistor optoisolator in a standard 6-DIP through-hole package. Its 4170Vrms isolation rating qualifies it for reinforced isolation between low-voltage control logic and mains-voltage circuits — think PLC digital inputs, motor-drive feedback, or SMPS secondary-side regulation.
CTR spread and switching speed — design margins
That 2:1 spread means the input resistor and pull-up must be sized for the worst-case 40% CTR across temperature and ageing. The output transistor saturates at 400mV max, keeping dissipation low when driving the 50mA output current into a 24V or 48V rail. Switching is moderate: 2µs turn-on and 3µs turn-off typical, with rise/fall times of 4µs and 3.5µs max. This suits status feedback at a few kHz or low-speed serial isolation, but not high-speed digital buses.