1500 W peak pulse — the clamping ceiling for 43.6 V rails
The 1.5KE51A-E3/51: The 70.1 V clamp means downstream components on a 48 V bus see no more than that during a surge — critical for MOSFET Vds or DC-DC converter abs-max ratings. The 1500 W rating assumes a 10/1000 µs pulse; shorter transients allow higher peak current, longer ones require derating.
Last Buy — sourcing reality for the BOM line
Vishay has placed the 1.5KE51A-/51 in Last Buy status. This is not a current-production part for new designs; it is supported for existing BOM lines through the end-of-life inventory window. For a procurement buyer managing a last-time-buy, the key decision is quantity commitment: the 1500 W peak pulse rating and 43.6 V standoff are fixed, so the replacement path (if needed) must match both the clamping voltage and the DO-201AA axial footprint. No pin-compatible alternative is listed in the family data.
Through-hole DO-201AA — board fit and thermal path
The DO-201AA (DO-27) axial leaded package mounts through hole, with the cathode band indicating the unidirectional orientation. The 1.5KE series common footprint means the same PCB pad layout serves the full voltage range — a board designed for any 1.5KE part accepts this 51 V variant without layout changes. The bulk packaging (/51 suffix) ships in standard ammo-pack quantities; no tape-and-reel option is listed for this code.