18.8V standoff, 1500W peak — the clamping decision
The 1.5SMC22AHM3/H: Maximum clamping is 30.6V at 49A peak pulse current — this is the voltage the protected circuit sees during a surge. For a 24V automotive bus that sees load-dump transients, the 30.6V clamp stays below typical downstream component abs-max ratings, giving the margin the design needs.
AEC-Q101 Grade — qualified for the engine bay
AEC-Q101 qualification means this part passed the automotive stress suite: high-temperature reverse bias, temperature cycling, and ESD robustness at the die level. The single unidirectional channel handles positive transients relative to ground. For a 12V battery line that only sees positive surges (alternator load-dump, inductive kick from a relay), the Zener direction is the correct polarity — no need for a bidirectional part here.
Active production — sourcing posture for the BOM line
The DO-214AB (SMC) footprint is a common industry standard, shared with other 1.5kW TVS diodes from multiple manufacturers. If a second-source qualification is on the roadmap, the package and electrical window (18.8V standoff, 30.6V clamp) are the parameters to match — no board spin needed for a pin-compatible alternative.