Obsolete — what this means for the BOM line
The 1.5KE39HE3/54 is marked obsolete per the manufacturer lifecycle record. No official successor or second-source order code is listed by Vishay for this specific AEC-Q101 variant.
Clamping specs and the protection window
The reverse standoff voltage is 31.6 V, meaning it sits across a nominal 24 V or 28 V rail without conducting leakage. Breakdown triggers at 35.1 V minimum, and the clamping voltage at peak pulse current (26.6 A) is 56.4 V maximum — this defines the voltage the downstream circuitry must survive during a surge event. The 56.4 V clamp ceiling is the figure a protection design engineer uses to check the downstream component voltage ratings. If the bus capacitance or parasitic inductance is high, the actual clamp may exceed this at the device terminals — the 10/1000 µs pulse is the standard test condition, not a worst-case real-world transient.
Automotive grade and temperature envelope
This is the qualification level required for under-hood or chassis-mounted electronic modules in production vehicles. The through-hole DO-201AA axial package (also known as DO-27) allows the part to be hand-soldered or wave-soldered into existing PCB layouts without a board respin — useful when replacing a failed unit in a legacy ECU.