The 1.5SMC9.1CA-E3/9AT: The 1.5SMC9.1CA-/9AT ships in the DO-214AB (SMCJ) package — the standard SMC footprint that picks up standard solar-tinned solder pads and a recommended land pattern most EMS shops already have dialed in.
The clamping voltage of 13.4V is specified at 112A peak pulse current, which tells you the let-through voltage the downstream circuit sees when the transient hits the clamping threshold. The reverse standoff is 7.78V typical — the circuit runs at or below this without the TVS conducting. Breakdown minimum is 8.65V; once a transient drives the rail above that threshold, the Zener clamps and the 13.4V ceiling protects the downstream silicon. For a 5V or 12V rail this part sits comfortably above the operating voltage with enough headroom to stay silent in normal operation.
Temperature grade and thermal margin
Junction temperature range is -65°C to 150°C — that covers the full industrial band and sits at the automotive threshold. At the 150°C ceiling the Zener characteristic shifts, so for a continuously clamped fault (not just a spike) the thermal impedance of the board-mounted package determines whether the part survives the event. Thermal relief pads and adequate copper under the cathode tab are the board-level variables that matter here.
It is a general-purpose bidirectional TVS Zener from a well-established series, so allocation risk is low.