1500 W peak pulse — clamping a 40.2 V rail
The 1.5SMC47A: It protects a 40.2 V reverse standoff rail — the nominal operating voltage it leaves undisturbed — and clamps transients at 64.8 V maximum when the surge current hits 23.5 A. With a breakdown voltage range starting at 44.7 V minimum, the device stays transparent below the rail voltage and only conducts when the transient exceeds that threshold. This is the standard selection logic for a DC bus or signal line that must ride through surges without interrupting normal operation.
DO-214AB SMC — board-fit and thermal path
The large tab area on the SMC body conducts heat from the die to the PCB copper during a pulse — the 1500 W rating assumes a standard footprint with adequate pad area for thermal sinking.