Voltage ratings that govern TVS selection
The 1.5SMCJ110CA: The 110 V standoff and 122 V minimum breakdown define the window in which this diode stays off and lets the circuit run normally — the 177 V clamping ceiling is the number that actually matters when a transient arrives, because it is what the downstream load sees during the event.
Junction temperature and the design margin question
DO-214AB (SMC) is the standard surface-mount outline for this power class — the large die attach and clip-bond construction give it lower thermal resistance than a smaller package of the same rated power, which directly translates to better survivability on fast transients.
Bidirectional clamping for AC and floating rails
Single bidirectional channel means it clamps symmetrically on both polarities — correct for AC lines, differential bus protection, or any rail where neither side is guaranteed to be ground. This is not a power-line protection device (the listing explicitly marks power line protection as no), so it protects a signal or low-power distribution rail, not a mains input.