The 1.5SMC51CAHR7G: That 1500 W figure defines the maximum transient energy the die can absorb without failing — for a 22 A peak pulse current, the clamping voltage holds at 70.1 V max. The reverse standoff voltage is 43.6 V, so this part protects a 43.6 V rail by breaking down at 48.5 V min and clamping the surge before it reaches downstream silicon.
AEC-Q101 — the automotive qualification that governs the screening
AEC-Q101 Grade means this TVS passed the automotive discrete semiconductor stress tests: high-temperature reverse bias, temperature cycling, and ESD robustness. For a 24 V truck or 48 V mild-hybrid bus, the 43.6 V standoff sits well below the nominal rail, so the diode stays transparent until a load-dump or inductive kick transient arrives.