1500W peak pulse power — sizing the transient clamp
That 1500W rating defines the energy it can absorb from a surge without failing — the design decision is whether the transient energy on your 40V rail stays under that ceiling. The 40V reverse standoff voltage matches the nominal DC rail voltage; the diode remains transparent below that level and only clamps when the line exceeds the breakdown threshold.
Clamping voltage and peak current — what the protected circuit sees
That 84V is the voltage the downstream components must survive — if your 40V bus feeds a converter rated for 60V absolute max, this part leaves no headroom. The breakdown voltage range starts at 44.4V minimum, so the diode begins conducting before the rail reaches damaging levels. The single bidirectional channel handles both positive and negative transients, which simplifies layout for AC-coupled or floating lines.
For production BOMs, this means no near-term supply discontinuity.