Four-channel unidirectional isolation in a 20-SSOP
The ADUM1445ARSZ is a 4-channel, unidirectional digital isolator from Analog Devices' iCoupler series, using magnetic coupling to provide 3750Vrms galvanic isolation across the barrier. It is a general-purpose device rated for 2Mbps data rate with 25kV/µs minimum common-mode transient immunity, making it suitable for breaking ground loops and protecting low-voltage logic in industrial fieldbus, motor-drive feedback, and isolated sensor interfaces.
The 3750Vrms isolation rating is a 1-minute withstand test per basic insulation requirements — enough for reinforced isolation in many 240VAC mains-connected designs when combined with proper creepage on the PCB. The 25kV/µs common-mode transient immunity means the part will not latch or corrupt data when a motor drive or inverter switches a high-voltage rail at microsecond edges; this is the spec that separates an isolator that works in a VFD from one that glitches. With all four channels on the same side of the barrier (4/0 input/output configuration), this variant is intended for applications where all isolated signals travel in one direction — for example, reading four digital sensor outputs or passing a parallel control word from a low-voltage controller to a high-side gate driver.
Supply range and timing — fitting the 3.3V logic rail
The 2.25V to 3.6V supply range lets the ADUM1445ARSZ run directly from a 3.3V or 2.5V rail without an extra regulator. Propagation delay is 180ns max each direction, with 8ns max pulse-width distortion — tight enough for 2Mbps SPI clocking or UART framing at 115200 baud, but not for high-speed parallel buses. Rise and fall times are 2ns typical, which keeps edge-rate induced ringing manageable on short PCB traces. The 20-SSOP footprint is a 5.30mm-wide body, 0.209-inch pitch — a common outline that fits most standard isolation layouts.