Automotive-grade clamping for 43.6 V rails
The 1.5KE51CAHE3/51: Its 43.6 V reverse standoff voltage protects 48 V nominal power buses, while the 70.1 V maximum clamping at 21.4 A peak pulse current (10/1000 µs waveform) limits the overvoltage seen by downstream electronics during load-dump or inductive-switching transients. The AEC-Q101 grade means the part has passed the full automotive stress suite (HBM, CDM, temperature cycling, high-temperature reverse bias) and is supported by PPAP documentation an OEM auditor will accept.
No power line protection — pure signal-rail clamping
The 1.5KE51CAHE3/51 is explicitly flagged as having no power line protection — it is a Zener-type TVS optimised for signal or low-impedance DC rails, not for AC mains or high-energy power distribution. The bidirectional configuration (single channel) clamps symmetrical positive and negative transients, making it suitable for differential data lines or bipolar supply buses where the polarity of the surge is unknown. The 70.1 V clamping ceiling at the 21.4 A peak current sets the maximum voltage the downstream silicon sees; a 60 V-rated downstream device has 10 V of margin before avalanche.
Obsolete — sourcing through independent channels
Vishay has marked the 1.5KE51CAHE3/51 as obsolete. No official successor part number is recorded from the manufacturer. The do-201AA axial footprint is common across the 1.5KE family, so a pin-compatible functional equivalent from the same series may exist, but no direct replacement is published by Vishay. Because the part is obsolete, any last-time-buy (LTB) window has already closed. Procurement should treat this as a managed EOL item — secure enough inventory for the remaining production run or qualify a drop-in from another manufacturer's 1.5 kW bidirectional TVS portfolio. The AEC-Q101 qualification limits the pool of direct substitutes; non-automotive equivalents may lack the PPAP and temperature cycling data an automotive OEM requires.