The minimum breakdown of 94.4 V is where the device first begins to conduct, and the clamping voltage of 137 V at 10.9 A peak pulse tells you what the downstream load actually sees during a 10/1000 µs surge event. For a 48 V nominal rail this gives you roughly 1.1× headroom in normal operation and a clamping ratio of about 2.8× under surge — the gap between 94.4 V breakdown and 137 V clamping is the margin the series impedance of the rail and any upstream fuse or inductor must buy you before the TVS takes over. This is a unidirectional device — it protects a positive-going transient relative to ground, not a bidirectional AC rail. For a 48 V positive bus with transients referenced to ground, the 1.5SMCJ85A does the job. For a dual-polarity or AC line you would need the bidirectional variant.
Peak pulse power and current ratings
The 1500 W peak pulse rating (1.5 kW) defines the device's energy-withstand capability in the standard 10/1000 µs waveform — this is the IEC 61000-4-5 surge class test wave shape, so the spec maps directly to what the device survives in a compliance test. At that same 10/1000 µs waveform the peak pulse current is 10.9 A; this is the current the TVS actually shunts during the event, and your upstream protection (fuse, PTC, or supply current limit) must survive the same event without opening the protected rail upstream of the TVS.
DO-214AB package and thermal environment
The SMC (DO-214AB) package is the standard footprint for 1500 W unidirectional TVS diodes across multiple manufacturers — a board laid out for this footprint can accept pin-compatible parts from other sources without a spin. Junction temperature range is -50°C to 150°C, which covers industrial enclosures and outdoor enclosures without derating concerns at room ambient — the 150°C ceiling is the thermal limit, so monitor board-level temperature rise under sustained overload conditions.