1500W peak pulse — the clamping decision
The 1.5SMC27: That 1500W rating means this single device can absorb a transient energy pulse that would otherwise propagate into downstream silicon — the clamp voltage of 39.38V at 40.5A peak pulse current sets the protection ceiling for the rail it guards. The reverse standoff voltage is 23.1V, with a minimum breakdown of 24.35V. This gives a 1.25V guard band between normal operating voltage and the point where the device starts conducting — tight enough that a 24V rail needs to stay clean of transients below that threshold.
DO-214AB footprint — board-fit reality
Housed in a DO-214AB (SMC) package, the same footprint as the SMCJ industry standard. The unidirectional channel means a single die in the package — cathode band on the body marks the polarity. No power line protection (the device is a standalone transient suppressor, not a filtered TVS array).
For a BOM that already carries this part, the existing layout and clamp voltage spec remain valid as long as stock is sourced. No pin-compatible direct replacement from Littelfuse is documented, so a board spin would be required to substitute a different TVS series.