What the 1.5SMCJ28A does and where it fits
The 1.5SMCJ28A_R1_00001: General-purpose classification means it lands on signal lines, low-power power rails, and bus interfaces that need clamping without latching.
The three voltage numbers that govern TVS selection
The reverse standoff of 28V is the maximum operating voltage the protected rail sits at under normal conditions — the TVS stays off and contributes no leakage until the line exceeds this. Once a surge drives the line above the 31.1V minimum breakdown, the TVS avalanches and clamps. The 150°C junction temperature rating reflects the die thermal margin — a wide band that suits outdoor enclosures and industrial ambient without derating concerns until the board-level thermal design runs tight.