The Renesas NEPOC PS9821-2-AX is a two-channel optocoupler packing a 15 Mbps data rate across a 2500 Vrms isolation barrier, with open-collector outputs on the secondary side. It is designed for DC input only and comes in an 8-pin SOIC surface-mount package (0.154" body width). The 15 Mbps ceiling handles most fieldbus interfaces (RS-485, CAN, Profibus DP up to 12 Mbps), PLC digital inputs, and encoder feedback lines — any place you need galvanic isolation without sacrificing signal integrity at moderate speed.
15 kV/µs CMTI — the spec that matters in switching environments
Common-mode transient immunity is rated 15 kV/µs minimum. That number tells you the optocoupler will not glitch or latch when a motor-drive IGBT switches 600 V in 40 ns — the dV/dt couples capacitively across the isolation barrier, and if the CMTI is too low the output toggles falsely. At 15 kV/µs this part is comfortable in variable-frequency drives, servo amplifiers, and UPS systems where high-side floating supplies create fast common-mode edges. The 75 ns propagation delay (max, both directions) keeps the total loop delay tight enough for most industrial closed-loop control.
Two channels in one SOIC-8 — board-space math
Two isolated channels in a single 8-pin SOIC-8 saves about 40% board area versus two single-channel optocouplers in separate packages. The forward voltage is typical 1.65 V, and the LED drive current maxes at 15 mA per channel. Output sink current is rated 25 mA per channel, which drives standard logic inputs or small relays directly.
Temperature range and supply — industrial environment ready
If your secondary side runs at 5 V, you need a level shifter or a different optocoupler rated for 5 V supply. The 2500 Vrms isolation is sufficient for basic functional isolation in most industrial equipment (IEC 60950-1 reinforced at 250 Vrms working voltage). For applications requiring 5 kVrms or higher, look at the NEPOC series with reinforced isolation ratings.
Active lifecycle — no LTB headache for production planning
The PS9821-2-AX is the two-channel version you want for isolated dual-line interfaces.