8.5V rail clamp in a DO-214AA footprint
The SMBJ8.5CA-13: Its 14.4V maximum clamping voltage at 41.7A peak pulse current (10/1000µs waveform) means a downstream 12V-rated IC sees the spike clipped before the oxide breaks down.
What the 600W rating means for your protection budget
The 600W peak pulse power is rated with a 10/1000µs exponential waveform — the standard telecom surge. For shorter transients (8/20µs, common in ESD or lightning indirect), the part can absorb significantly more peak current because the energy per pulse drops with the pulse width. The 41.7A peak pulse current at the 10/1000µs condition is the conservative figure to use for worst-case coordination with the upstream fuse or PTC. The bidirectional configuration means it clamps both polarities symmetrically, which suits AC-coupled data lines or DC rails that see reverse-voltage transients.