400W peak pulse, 85V standoff — where it lands on the rail
The SMAJ85A-13-F: Its 85V reverse standoff voltage places it on a nominal 85V DC rail or a 60V AC line — the clamping threshold at 137V means downstream silicon sees a hard ceiling before avalanche. Packaged in the DO-214AC (SMA) footprint, surface-mount, it handles the full 2.9A peak pulse current at the clamping voltage. The -55°C to 150°C junction range covers industrial and outdoor gear without derating at the hot end.
What the 400W rating means for a real fault
The 400W peak pulse power is specified with a 10/1000µs exponential waveform — the standard telecom surge shape. A 2.9A pulse at 137V clamping stays inside the 400W envelope. For shorter transients (8/20µs, common in ESD or lightning), the device absorbs significantly more peak current; the 400W rating is the conservative floor for a 1ms pulse. The 94.4V minimum breakdown voltage gives margin above the 85V standoff — the rail can ride up to 94V without the TVS conducting leakage. Below that, the part is effectively invisible to the circuit. Power line protection is marked 'No', meaning it is not optimized for repetitive AC line clamping; use it on DC rails or signal lines.