What the 15V standoff and 24.4V clamping mean for your protection circuit
The 1.5SMCJ15AS_R1_00001: The 15V reverse standoff sets the working voltage above which the TVS begins to avalanche — transients below 15V pass through unclamped, which is the correct behavior for a rail that runs clean most of the time. For a 15V rail, that roughly 1.6× clamping ratio is the design trade-off — tighter protection requires a lower standoff, looser standoff reduces clamping duty on normal operation.
DO-214AB SMC footprint and SMT assembly
The DO-214AB (SMC) is the standard package for 1.5kW+ TVS diodes — the wide metal slab tab carries the peak pulse current during a clamp event without thermal runaway. The device is unidirectional — for bidirectional protection across an AC line, two devices in inverse series or a dedicated bidirectional TVS is required.