TVS diode — standoff, breakdown, and clamping
The 1.5SMC68CA/TR13 is a bidirectional TVS Zener in the 1.5SMC series, specified with a 58.1 V typical reverse standoff voltage — the normal operating rail the protected node sits at continuously. Breakdown triggers at a minimum of 64.6 V, clamping the transient to 92 V maximum at the rated 16.5 A peak pulse current using the 10/1000 µs waveform. The clamping voltage — 92 V — is the stress the downstream circuit sees during a surge event; selecting a TVS whose standoff sits above the working rail but whose clamping ceiling stays below the protected node's absolute maximum rating is the core selection decision.
DO-214AB SMC — reel packaging and thermal rating
Power-line protection is listed as No, which classifies this as a component-level TVS rather than a board-level mains protection device — it protects signal and low-power rails, not the AC input stage.