1500 W pulse rating and what it means on a 15 V rail
The 1.5SMC18AHM3/I is a 1500 W peak-pulse-power TVS diode from Vishay's 1.5SMC TransZorb® series, with a 15.3 V reverse standoff voltage and a 25.2 V clamping point at 59.5 A peak pulse current (10/1000 µs waveform).
AEC-Q101 and the -65 to 150 °C operating range
The junction temperature range spans -65 °C to 150 °C, so it survives cold-crank at -40 °C and hot soak at 125 °C with margin to the absolute max.
DO-214AB package and reflow handling
Housed in a DO-214AB (SMC) package, the part sits on a standard surface-mount footprint with the cathode band marking polarity. The large tab area on the SMC body helps conduct pulse heat into the PCB copper — keep the pad size per the Vishay application note to stay within the 1500 W derating curve. No power-line protection (unidirectional Zener only), so it clamps one polarity — use it on a single-rail bus where the transient is positive-going relative to ground.