Four input-side channels — where the direction matters
The ADUM4400ARWZ-RL is a 4-channel unidirectional digital isolator from Analog Devices' iCoupler series, using magnetic coupling to pass signals across a 5000Vrms isolation barrier. All four channels are configured with inputs on Side 1 and outputs on Side 2 (4/0), which means this variant is strictly for signals flowing from the microcontroller side to the isolated side — not for bidirectional lines or mixed-direction buses like RS-485 without external direction gating. The 1Mbps data rate suits optocoupler-replacement designs for industrial fieldbus, PLC I/O modules, and isolated SPI/UART links where throughput stays under 1 Mbps.
25kV/µs CMTI — surviving the switching edge
A minimum common-mode transient immunity of 25kV/µs is the spec that matters when this isolator sits between a PWM controller and a motor-drive IGBT or SiC half-bridge. If the switching node slews faster than the CMTI rating, the isolator's output can glitch, injecting false edges into the logic. At 25kV/µs the ADUM4400 handles most industrial inverter edges up to the 10-20kV/µs range common in 600V class drives, but GaN designs pushing 100kV/µs will need a higher-rated part. Propagation delay is 100ns max symmetrical (tpLH/tpHL), with 40ns max pulse-width distortion — tight enough for 1Mbps signaling but not for time-critical current-sense feedback loops that need sub-50ns latency.
Supply-rail flexibility and package reality
The 3V to 5.5V supply range on both sides lets you run the primary from a 3.3V MCU rail and the secondary from a 5V isolated bus transceiver without a dedicated regulator. The wide-body 16-SOIC (7.50mm body width) provides the 8mm creepage typical for reinforced isolation in medical and industrial applications — verify your PCB's clearance and creepage targets against the 5000Vrms rating.