4-channel isolator with 125°C capability
The ADUM3481ARSZ-RL7 is a 4-channel, unidirectional digital isolator from Analog Devices' iCoupler series, using magnetic coupling to transfer logic signals across a 3750Vrms isolation barrier. It operates from 1.8V to 5.5V on the low-voltage side and 3V to 5.5V on the high-voltage side, with a maximum data rate of 1Mbps. The 3/1 input-side/side-2 channel count means three channels drive from side 1 to side 2, one channel drives the opposite direction — a common configuration for SPI or UART isolation where the chip-select or data-direction signal runs back.
Timing and transient immunity — the practical limits
Propagation delay is 90ns max in either direction, with a pulse-width distortion ceiling of 6ns. That 90ns round-trip eats into the timing budget for a 1Mbps SPI clock — at 1Mbps the bit period is 1µs, so the isolator consumes about 18% of the window in one direction. For slower UART or GPIO isolation at 115.2 kbps or below, the delay is negligible. The common-mode transient immunity is rated at 25kV/µs minimum, which handles the noise spikes from a motor-drive inverter or a relay bank without corrupting the output state.
Package and supply rails
Housed in a 20-SSOP with 0.209-inch body width (5.30mm), surface-mount only. The supply pins accept 1.8V to 5.5V on one side and 3V to 5.5V on the other, so it can bridge a 1.8V MCU to a 3.3V or 5V peripheral. No isolated power on-chip — you still need a separate DC-DC or an isolated module to power the secondary side if the barrier crosses a ground potential difference.