Last-buy status and what it means for your BOM
The 1.5KE400A-E3/51: Vishay has placed the 1.5KE400A-/51 on Last Buy status — this is the final procurement window before the part becomes unavailable through authorized channels. Any open BOM line using this order code should be reviewed for a last-time-buy quantity or a qualified replacement before the window closes. Sourcing through independent distribution remains viable for bridge quantities, but a board-spin to an active alternative should be planned for production continuity.
The reverse standoff voltage of 342V means the diode does not conduct at normal operating voltage; it only begins to avalanche at the minimum breakdown of 380V. That 548V clamp is the voltage the downstream components must survive — a critical number for the semiconductor stress rating on the protected line. The single unidirectional channel protects one polarity rail. For AC or bidirectional lines, two devices or a bidirectional variant would be needed.
Temperature range and package fit
The wide range suits outdoor telecom rectifiers, motor-drive DC buses, and battery-charger output stages. Housed in a DO-201AA (DO-27) axial leaded package, it mounts through-hole — the same footprint as standard 1.5KE series devices. The axial form factor is straightforward to hand-populate or wave-solder, and the bulk packaging (/51 suffix) ships in standard tubes or ammo pack.