Clamping voltage and peak pulse rating
The 1.5SMC68A_R1_00001: The 58.1 V reverse standoff means the device draws only leakage current under normal rail conditions, staying passive in the circuit until a transient pushes the node above that threshold; above 64.6 V it breaks down and clamps the excursion to 92 V.
Temperature and package
Junction temperature is rated to 150 °C — the Tj ceiling, not ambient — so a board running at elevated ambient still has headroom as long as the transient duty stays within the peak pulse spec. Surface-mount SMC package accepts standard reflow profiles; the DO-214AB footprint is widely supported across the 1.5SMC series, so a layout designed for this part can accommodate variants across the family without a board spin.