15 V standoff, 26.9 V clamp — what the numbers mean
The 1.5SMCJ15C: At 15 V reverse standoff (typ), the device sits invisible across the rail; when a transient exceeds the 16.7 V breakdown threshold, it clamps the line at 26.9 V maximum and shunts 55.8 A peak away from the protected circuit. That clamping voltage is the ceiling the downstream IC never sees, so selecting a standoff comfortably below the working rail but below the IC abs-max is the primary sizing move — 15 V sits cleanly above a 12 V nominal rail with margin for line variation.
SMC/DO-214AB surface-mount footprint
The DO-214AB package is the larger SMC variant — wider than the SMA (DO-214AC) footprint. The supplier device package is SMC/DO-214AB. The cathode band marks polarity on the tape strip orientation, which matters for automated pick-and-place programming. Junction temperature rating is -50°C to 150°C, so the thermal pad under the body must conduct heat to the PCB copper to stay within that window at full peak pulse current.