The ADuM3400/ADuM3401/ADuM34021 are 4-channel digital isolators based on the Analog Devices， Inc.， iCoupler? technology. Combining high speed CMOS and monolithic air core transformer technology， these isolation components provide outstanding performance characteristics superior to alternatives such as optocoupler devices. iCoupler devices remove the design difficulties commonly associated with optocouplers. Typical optocoupler concerns regarding uncertain current transfer ratios， nonlinear transfer functions， and temperature and lifetime effects are eliminated with the simple iCoupler digital interfaces and stable performance characteristics. The need for external drivers and other discrete components is eliminated with these iCoupler products. Furthermore， iCoupler devices consume one-tenth to one-sixth the power of optocouplers at comparable signal data rates. The isolators provide four independent isolation channels in a variety of channel configurations and data rates （see the Ordering Guide）。 All models operate with the supply voltage on either side ranging from 3.0 V to 5.5 V， providing compatibility with lower voltage systems as well as enabling a voltage translation functionality across the isolation barrier. The isolators have a patented refresh feature that ensures dc correctness in the absence of input logic transitions and during power-up/power-down conditions.