Four-channel transistor-output optocoupler for industrial signal isolation
The Renesas PS2841-4B-F3-AX is a 4-channel DC-input transistor-output optocoupler from the NEPOC series, packaged in a 12-BSOP surface-mount package. It provides 1500Vrms of galvanic isolation between a low-voltage control side and a higher-voltage output side, with each channel rated for 20mA output current and a maximum output voltage of 70V. The current transfer ratio spans 100% to 400% at 1mA forward current, giving the designer room to trade off LED drive current against output saturation margin. Typical applications include PLC digital input modules, industrial sensor interfaces, motor-drive status feedback, and any board-level isolation where four independent channels in a single small-footprint package reduce component count.
The 1500Vrms isolation rating is the reinforced-safety figure for this optocoupler. It suits basic isolation in 24V or 48V industrial buses where the working voltage stays well below 300V peak. For applications requiring 2500Vrms or higher (e.g., mains-referenced circuits), a part like the PS2801C-4-V-A with its 2500Vrms rating would be the next step up. The 1500Vrms level here keeps the package small and the coupling capacitance low, which matters for common-mode transient immunity in noisy factory-floor environments.
CTR range and switching speed
With a CTR guaranteed between 100% and 400% at 1mA forward current, the PS2841-4B-F3-AX gives predictable output saturation across temperature and LED aging. At the minimum CTR, 1mA in yields at least 1mA out — enough to drive a logic gate input or a small relay coil through a transistor buffer. The 20µs rise and 110µs fall times are typical for a phototransistor output; this part is not intended for high-speed data isolation but for DC-level sensing, switch-status readback, and low-frequency signal transfer where the 110µs fall time is well within the timing budget.
Temperature range and output voltage headroom
The 70V maximum output voltage provides ample margin for 24V and 48V bus levels, and the 300mV Vce saturation at rated current keeps power dissipation low in the output transistor. The 12-BSOP package with 4.40mm body width fits compact PCB layouts where four discrete optocouplers would consume too much board area.
Lifecycle and sourcing posture
For dual-sourcing consideration, the PS2801C-4-V-A is a functional peer with 2500Vrms isolation and faster switching (5µs rise, 7µs fall), but note the different package and CTR spec — verify pin compatibility before substituting.