The 1.5KE18: The DO-201AA axial package (also known as DO-27) handles the thermal pulse through its lead-frame body, and the through-hole mounting keeps the device mechanically secure on the board.
Obsolete — sourced through independent channels
Littelfuse has marked the 1.5KE18 as obsolete. The 1.5KE series covers a broad voltage range, so a parametric replacement (different breakdown voltage) may exist within the same family, but no pin-compatible drop-in is documented. A board-level review of the clamping and standoff requirements is advised before substituting.
Temperature range and general-purpose deployment
The general-purpose application classification means no specific automotive or military screening — the part is a standard off-the-shelf TVS for board-level transient suppression.