What this 1.5 kW bidirectional TVS actually protects
The 1.5KE440CA-E3/51: With a single bidirectional channel, it protects signal or power lines that see both positive and negative transients, eliminating the need for two diodes back-to-back.
Package and board-fit: DO-201AA axial leaded
Housed in a DO-201AA (DO-27) axial-lead package, this is a through-hole part — the leads are inserted into plated holes and soldered on the opposite side. The axial form factor is common in high-reliability and high-surge designs where a surface-mount part might not handle the mechanical stress of repeated pulse events. The operating junction temperature range spans -55°C to 175°C, covering industrial and some automotive under-hood environments where the ambient can exceed 125°C.
Lifecycle reality: obsolete, sourced through independent channels
For a BOM that still calls out this exact part, supply runs through independent surplus and broker channels.