What this isolator delivers on the bus
The 3/1 input-side/side-2 split gives you three forward channels and one reverse channel — a common arrangement for isolated SPI (SCLK, MOSI, CS forward, MISO reverse).
Transient immunity and industrial noise
A lower CMTI spec risks data corruption when fast high-voltage edges couple across the barrier. At this level the part holds data integrity through the kind of switching transients you see in industrial drives, solar inverters, and UPS systems. The capacitive coupling technology inherently handles these edges better than optocouplers, which degrade with age and temperature.
The wide range also covers the thermal cycling seen in HVAC and building automation.