What the clamping specs mean for the protected circuit
The 1.5SMCJ45C: The 45V reverse standoff rating is the working voltage — the line sits at or below this in normal operation, and the TVS presents a high-impedance path. When a transient exceeds the standoff, the device avalanche-breaks down at the 50V minimum breakdown and clamps the spike to 80.3V maximum. That clamping ceiling is the voltage the downstream load actually sees — for a 45V rail, 80.3V is within most CMOS and comparator absolute-maximum ratings, so this part protects typical 24V and 40V industrial rails cleanly. At that energy level the part absorbs 1.5 kW of peak pulse power, which is what qualifies it for distribution panel, bus overvoltage, and relay-contact arcing environments. A faster edge event (8/20µs) at the same current would deliver more peak power — the 1.5 kW figure is specific to the 10/1000µs test condition cited on the datasheet.
Package and thermal margins for board-level integration
The DO-214AB (SMC) package with tin-lead finish accepts reflow or wave assembly. Junction temperature is rated to 150°C with the thermal derating curve in the Diotec datasheet setting the real-world current limit at elevated ambient — for a 24V rail the clamping duty at typical surge energy is low enough that the thermal margin holds without a dedicated heatsink pad. The -50°C minimum junction rating makes this suitable for outdoor equipment enclosures and cold-start industrial environments where the TVS must survive before the bulk supply rails have fully charged.