1500 W peak pulse — the protection envelope
The 1.5SMC43AHE3/9AT: That 1500 W rating defines the energy it can clamp in a single surge event; the actual protection level is set by the 59.3 V maximum clamping voltage at the 25.3 A peak pulse current.
36.8 V standoff — the continuous rail it rides
Breakdown starts at a minimum of 40.9 V, so a 36 V supply bus stays protected without the diode conducting during normal operation. The unidirectional channel (single) biases with the cathode toward the positive rail — correct orientation matters for the clamping path.
AEC-Q101 — the automotive pedigree
This part carries AEC-Q101 qualification, the automotive discrete semiconductor stress test standard. No power line protection (it is a transient suppressor, not a crowbar circuit).
DO-214AB SMC — the board footprint
Surface-mount DO-214AB (SMC) package, also known as SMCJ. The copper pad area under the cathode tab sets the thermal resistance to the board — a larger pad lowers the junction temperature rise for a given surge duty cycle.