What the clamping and breakdown specs mean for the BOM
The 1.5SMC15AHM6G: The minimum breakdown voltage of 14.3V sets the threshold where the TVS starts conducting — a 12.8V nominal rail must stay below this during normal operation, or the diode will leak and eventually clamp on transients that are within the system's normal ripple budget. At 21.2V clamping, the TVS limits the peak voltage seen by downstream components during a 74A surge event — this is the figure a board designer uses to verify that the downstream IC's absolute-maximum rating is not exceeded. The DO-214AB (SMC) package is the standard footprint for 1500W TVS diodes — the copper pad area on the PCB under the cathode tab directly sets the junction-to-ambient thermal resistance, so the board layout must follow the recommended land pattern to achieve the rated pulse power.