Digital isolator for industrial signal isolation — 3000 Vrms, 25 Mbps, two unidirectional channels
The Analog Devices ADUM1281BRZ-RL7 is a two-channel digital isolator from the iCoupler family, built around magnetic coupling technology. It provides 3000 Vrms of galvanic isolation between a single input on side 1 and a single output on side 2, with the second channel configured in the same direction — a 1/1 unidirectional arrangement. The part supports data rates up to 25 Mbps, making it suitable for isolating SPI, UART, or general-purpose digital signals in industrial control, motor drives, and isolated power-supply feedback paths.
The 3000 Vrms isolation rating is the working voltage the part can withstand between input and output sides for one minute per the production test. For a 240 VAC mains-referenced circuit, this provides reinforced insulation with margin. In practice, the 3000 Vrms rating covers most industrial applications where the isolated side is a sensor, encoder, or communication bus referenced to a different ground potential. The common-mode transient immunity of 25 kV/µs minimum means the part will not latch or corrupt data when fast voltage transients — typical in motor-drive PWM edges or relay switching — couple across the isolation barrier.
25 Mbps data rate and timing margins
At 25 Mbps, the ADUM1281BRZ-RL7 handles a 12.5 MHz clock or NRZ data stream with a 40 ns bit period. The maximum propagation delay of 35 ns in either direction leaves only 5 ns of timing margin for a full round-trip — tight for a closed-loop SPI transaction at 25 Mbps, but workable if the master and slave are on the same side of the barrier. The 3 ns maximum pulse-width distortion keeps the duty-cycle error small, which matters for protocols like RS-485 or CAN that rely on edge timing. Rise and fall times are typically 2.5 ns, so signal integrity on the PCB trace matters — keep the stub length under 15 mm from the isolator output to the receiving gate.
The 125°C upper limit covers engine-bay electronics, outdoor telecom cabinets in direct sunlight, and factory-floor sensors near hot machinery. The part is surface-mount only, so reflow soldering is assumed — no through-hole option exists.
It is ROHS3 compliant. No LTB risk exists for production programs that qualify this part today.