Obsolete TVS — what the ratings mean for a replacement search
The 1.5KE43CAHE3/51: The 36.8 V standoff means it protects 36 V nominal rails (common in 24 V automotive systems with transients) and starts clamping above 40.9 V breakdown, holding the line to 59.3 V maximum.
Housed in a DO-201AA (DO-27) axial leaded package, through-hole mount — the same footprint as the standard 1.5KE series, so a replacement from that family drops in without a board spin. The bulk packaging means it ships loose in a tube or bag, not taped and reeled — fine for hand assembly or low-volume rework, but not pick-and-place friendly.
Automotive-grade transient protection
The -55°C to 175°C operating junction range covers the full automotive temperature envelope, including engine-bay heat soak.