400W surge clamp for 160V rails
The SMAJ160A-13: The reverse standoff voltage of 160V means it sits across the supply without conducting during normal operation — the leakage stays negligible until a surge pushes the line above the 178V minimum breakdown threshold. Once triggered, it clamps the transient to 259V maximum, shunting up to 1.5A of the 10/1000µs surge waveform through the junction and into ground. This is a unidirectional device — the single Zener-like junction conducts only in reverse breakdown, so it protects one polarity rail. For AC lines or bipolar supplies, you would need two devices back-to-back or a bidirectional TVS. The 400W rating is the peak pulse power at the 10/1000µs test waveform; real-world surge energy depends on the pulse width and source impedance, but this part handles the typical IEC 61000-4-5 surge level for 160V telecom and industrial DC buses.
Housed in the standard DO-214AC SMA package, this TVS shares the same footprint as thousands of other 400W SMA parts — the pad layout is well-established, and the reflow profile matches typical lead-free soldering. The -55°C to 150°C junction temperature range covers both cold-start telecom cabinets and hot industrial enclosures; the 150°C upper limit means the part survives soldering heat and high-ambient conditions without derating the pulse power beyond the datasheet curve. The SMA body is small enough that the 400W rating is thermally limited by the copper pad area on the PCB — a solid ground-plane connection under the cathode tab pulls heat out of the junction during repetitive surges.