Unidirectional Zener TVS — clamping and standoff ratings
The 1N6384 is a unidirectional Zener-based TVS (transient voltage suppressor) in the ICTE/MPTE series — a general-purpose clamp diode intended to absorb voltage spikes and protect downstream circuits from overstress. It is classified as a Zener type, not a standard silicon avalanche diode, which means its breakdown behaviour follows the Zener knee at lower voltages and transitions into avalanche behaviour at the higher end of its operating range. For a 12 V rail, that gives roughly 5 V of headroom at idle and a clamp ceiling of 17.1 V under surge — which is the number that matters when you are protecting a bus that cannot exceed its abs-max rating. Faster, sharper transients (8/20 µs) deliver more current for a given energy, so a 70 A peak pulse at 10/1000 µs represents the safe upper bound for this waveform geometry; the same device at an 8/20 µs shape would clamp at a lower current for the same peak power.
Package, temperature grade, and through-hole rework
At the top end, a clamped surge that drives the junction toward 175°C will be limited by the thermal time constant of the package; the 1500 W rating is a pulse rating, not continuous, so a sustained overcurrent condition will push the device out of its safe operating area before the thermal limit is reached. The DO-201AA body is not a surface-mount thermal pad — heat removal is primarily through the leads into the PCB pads.