400W peak pulse — what that means on the bench
The SMAJ28A-13-F: That 400 W figure is the product of the clamping voltage and the peak pulse current — at the 45.4 V clamp, the device handles 8.8 A before the junction exceeds its thermal limit. The 28 V reverse standoff voltage (VRWM) means this part sits across a 24 V rail and does not conduct until the transient exceeds 31.1 V breakdown. The 45.4 V clamp is the voltage the downstream circuitry sees during the pulse — if your 24 V bus has a 40 V abs-max on the next IC, this TVS clamps below that threshold.
Surface-mount in DO-214AC (SMA), the body is roughly 4.6 mm long by 2.8 mm wide with a 2.0 mm height. The copper pad pattern under the cathode tab is the primary heat path — a 12 mm² pad on the top layer drops the thermal resistance significantly versus the minimum land pattern. The part is RoHS-compliant and halogen-free per Diodes' standard material declaration.