Clamping voltage and thermal margin
The 1.5SMC400CA/TR7: With a breakdown voltage minimum of 380 V, the diode starts conducting just above the 342 V standoff, leaving a 38 V window before the avalanche region. The operating temperature range of -65°C to 175°C covers military and industrial thermal profiles. At the high end, the leakage current through the Zener junction increases, but the 1500 W pulse rating is derated per the datasheet curve — at 175°C the peak pulse power is roughly 60% of the 25°C rating, so a hot enclosure reduces the effective surge capacity.
The tape-and-reel packaging (TR suffix) feeds into automated pick-and-place lines; the cut-tape option suits prototype or low-volume builds. A 1 oz copper pad with adequate thermal vias keeps the junction temperature rise within limits during repetitive surge events.
Active lifecycle and sourcing
The 1.5SMC series includes multiple voltage variants in the same DO-214AB footprint, so a BOM change to a different standoff voltage would require a new PCB qualification.