EOL — last-time-buy window closed
The 1.5KE51-E3/73: Vishay lists the 1.5KE51-/73 as obsolete. For a BOM line still calling out this part, the sourcing path is broker or surplus stock with date-code provenance verified at RFQ. No pin-compatible replacement from Vishay is documented.
1500 W peak pulse — what the rating governs
The clamping voltage at that peak current is 73.5 V max. Reverse standoff voltage is 41.3 V typical — the rail or signal line should stay below this level during normal operation. Breakdown occurs at a minimum of 45.9 V, giving roughly 4.6 V of guard band before the diode starts conducting. Peak pulse current is 20.4 A at the 10/1000 µs pulse. That figure sets the fuse-coordination floor: the TVS must clamp before the upstream fuse or breaker clears, so the I²t of the pulse stays inside the diode's SOA.
Unidirectional, through-hole, general-purpose
Single unidirectional channel — one diode per package, cathode banded. For bidirectional clamping on an AC signal pair, two devices or a bidirectional part are needed. DO-201AA (DO-27) axial leaded package, through-hole mount. The 0.042-inch lead diameter fits standard 1.0 mm PCB holes; the body length is roughly 9.1 mm. The 175°C TJ(max) is typical for silicon TVS diodes and allows the junction to absorb repetitive pulses without immediate failure, provided the average power stays within the derating curve.