Four isolated transistor outputs in a 16-SOIC
The Renesas NEPOC PS2811-4-F3-A packs four independent phototransistor optocouplers into a 16-SOIC (4.40 mm width) surface-mount package. Each channel provides 2500Vrms galvanic isolation between a DC-input LED and a phototransistor output, with a guaranteed current transfer ratio of 100% to 400% at a forward current of 1mA. The transistor outputs are rated for 40V and 40mA per channel, with a typical Vce(sat) of 300mV. This part is commonly used for isolating digital I/O, PLC input modules, motor-drive feedback, and industrial sensor interfaces where four channels share a common ground reference on the output side.
CTR range and LED drive margin
The 100% to 400% CTR range at 1mA If is the spec that determines logic-family compatibility and temperature margin. At the 100% minimum, a 1mA LED current guarantees at least 1mA of collector current in the output transistor — enough to pull a 5V TTL input low through a 4.7kΩ pull-up. The 400% maximum means the same 1mA drive can saturate the output transistor with 4mA of collector current, which covers CMOS logic and higher-impedance loads. The wide CTR spread also accounts for LED degradation over temperature and lifetime, so the 1mA test condition gives headroom for derating without redesigning the drive resistor.
Temperature range and isolation for industrial environments
Rated for -55°C to 100°C operating temperature, this optocoupler spans the full industrial temperature range plus cold-start conditions down to -55°C. The 2500Vrms isolation barrier suits equipment where the control side (MCU, FPGA) must be galvanically separated from a 24V or 48V field bus, motor phase, or sensor power rail. The 4µs typical rise and 5µs fall times support data rates up to roughly 100 kbps, which covers most PLC digital inputs, relay drivers, and status feedback lines.