What the 85 V standoff and 400 W pulse mean for your rail
The SMAJ85A-13: The 85 V reverse standoff means the device draws negligible leakage at normal operating voltage up to that level — it stays out of the circuit until a surge pushes the rail above the minimum breakdown of 94.4 V. For repetitive events or longer pulse widths, the device's thermal capacity in the DO-214AC package limits the energy per event; the datasheet derating curve (not reproduced here) governs the safe operating area for repeated surges.
Automotive temperature range and package fit
The DO-214AC (SMA) surface-mount package uses a standard footprint shared across the SMAJ family — the same pad layout accepts the 5 V through 170 V variants, simplifying BOM consolidation when multiple rail voltages need protection on one board. Marked as Automotive applications, the part is qualified for the reliability stress and temperature cycling requirements of that sector.
Sourcing and lifecycle posture
The SMAJ family includes multiple voltage variants sharing the same DO-214AC footprint, but a different standoff voltage is not a functional substitute — the 85 V rating is specific to this order code.