Transient suppression — what the clamping specs decide
The 1.5SMCJ170AS_R1_00001: The reverse standoff of 170 V sets the working voltage below which the TVS stays off and draws only leakage current — the line runs nominal at that rail. When a transient exceeds the breakdown threshold of 189 V, the device avalanches into conduction and clamps the peak at 275 V. That 275 V ceiling is the clamping voltage the downstream IC or bus sees, so the board-level protection bandwidth is set by this number, not the standoff. Peak pulse current is rated 5.5 A at the standard 10/1000 µs waveform — this is the surge shape produced by inductive kick and power-line disturbances in industrial and instrumentation equipment. The junction temperature swings within the rated 150 °C ceiling for that brief window; continuous or repeated surges at full amplitude require derating and thermal management at the board level.
The part carries Active lifecycle status under Panjit International Inc. — franchised distribution stocks it alongside independent surplus when the cycle flips. For new designs the part is orderable under the listed MPN; for legacy maintenance the independent channel covers gaps when franchised stocks thin out during shortage windows.