Vishay has marked the 1.5KE51HE3/54 as obsolete. Sourcing this part now goes through independent distribution channels — surplus, new-old-stock, or broker inventory — with availability and pricing confirmed at the time of an RFQ. The last-time-buy window has closed. Any units in the channel carry their original date codes, so lot traceability and authenticity screening are the buyer's due diligence. A functional replacement requires a board-level review of the DO-201AA footprint and the 41.3 V standoff / 73.5 V clamping profile.
AEC-Q101 qualification and the TransZorb series
This part belongs to Vishay's TransZorb series with an AEC-Q101 automotive qualification — it has passed the stress tests and reliability screening required for under-hood and chassis-mounted electronics in passenger and commercial vehicles.
Voltage thresholds and clamping performance
The reverse standoff voltage is 41.3 V — the TVS draws negligible leakage below this level. These three numbers define the protection window: the rail being protected must tolerate the clamp voltage without damage, and the normal operating voltage must stay below the standoff.
Through-hole package and board fit
Supplied in the DO-201AA axial-lead package (also known as DO-27), this is a through-hole device. The lead spacing and body diameter match the industry-standard 1.5KE footprint, so a replacement TVS in the same package style fits the existing PCB holes without layout changes. The unidirectional configuration protects one polarity rail. For bidirectional or AC-line applications, two devices back-to-back or a single bidirectional part would be needed.