TVS clamp margin for a 28V rail
The SMCJ28CA-13-F: Its 28V reverse standoff voltage means it sits across a 28V nominal rail without conducting in normal operation; the breakdown triggers at 31.1V minimum, clamping the surge to 45.4V maximum while shunting 33A peak pulse current. That 45.4V clamp is the ceiling the downstream circuitry must survive — if your DC-DC converter or load switch has an abs-max input below that, this TVS alone won't protect it.
The SMC footprint is larger than the SMA/SMB siblings — the wider body and thicker copper tab carry the 1500W pulse without exceeding the junction temperature ceiling of 150°C. For a 28V rail in an industrial or telecom PSU, the pad area under the cathode (anode for bidirectional) should match the recommended land pattern in the datasheet to keep the thermal impedance low enough for repetitive surges.
The SMCJ28CA-13-F is a standard-production part from Diodes Incorporated, available through independent and authorized distribution.