2500Vrms isolation in a 4-pin mini-flat package
The NEC PS2911-1-V-AX is a single-channel DC-input phototransistor optocoupler rated for 2500Vrms galvanic isolation. It comes in a 4-SMD flat-lead package (supplier device package 4-Mini-Flat) for surface-mount assembly.
CTR range and drive margin
Current transfer ratio is guaranteed between 100% and 400% at a forward current of 1mA. That 4:1 min-to-max spread is typical for phototransistor couplers, but the 100% floor at only 1mA drive means you can run the LED side at low current and still get enough photocurrent to saturate the output transistor. For designs that need to guarantee logic-level output over temperature and LED aging, the 100% minimum CTR at 1mA gives comfortable headroom.
Switching speed and output ratings
Turn-on time is 40µs typical, turn-off time 120µs typical. That's in the range of standard phototransistor couplers — fine for 50/60 Hz AC sensing, relay replacement, or PLC digital inputs, but not for high-speed serial isolation. The output transistor is rated for 40V maximum collector-emitter voltage and 40mA continuous output current, with a saturation voltage of 300mV max at that current. The LED side accepts up to 50mA forward current, with a typical forward voltage of 1.1V.
