The 1.5SMCJ6.5: For a 5 V or 12 V DC rail, 12.3 V sits safely above the rail but well below the withstand rating of most ICs and MOSFET gates on that bus. The 1.5 kW peak-pulse rating is the short-duration absorption spec, not continuous — it defines the device's ability to survive a single 10/1000 µs surge without degradation or failure, so the clamping voltage holds across the event.
The SMC (DO-214AB) package is the mid-range SMC footprint — the cathode bar on the package face identifies the polarity direction, and the single-channel unidirectional configuration means it protects one polarity only. Bidirectional protection requires a different part type. The surface-mount form factor accepts reflow profiling; the cathodic termination metal pad must be thermally coupled to a copper pad on the board for peak-pulse thermal management — the package alone does not dissipate a full 1.5 kW surge, the board tab carries the heat away from the junction during the transient event.
Operating temperature and junction limits
The actual board-level ambient derating must be applied per the thermal resistance curve in the Diotec datasheet to ensure the junction stays below 150°C under worst-case sustained operation. Transient surge heating is self-limiting by the short 10/1000 µs waveform duration; continuous or repetitive surges that heat the junction above 150°C will shift the breakdown voltage over time.