1500 W peak pulse, 7.37 V standoff — the clamping envelope for a 12 V automotive rail
The 1.5KE9.1HE3/73: It clamps a 10/1000 µs surge at 13.8 V maximum while the reverse standoff voltage sits at 7.37 V — this puts the protection window squarely over a nominal 12 V battery line, where the standoff keeps the diode out of conduction during normal operation and the clamp catches load-dump or inductive kick transients before they reach downstream silicon. The breakdown voltage range starts at 8.19 V minimum, so the diode begins to avalanche well before the clamp voltage is reached — this built-in margin means the TVS absorbs the surge energy without the part itself failing open or short.
DO-201AA axial-lead — board integration and thermal path
Housed in a DO-201AA (DO-27) axial-lead package, the 1.5KE9.1HE3/73 is a through-hole part intended for point-to-point wiring or PCB mounting with the leads formed to the hole pitch. The package is supplied in Tape & Box (TB), which is a bulk axial-lead format — not reeled for automated insertion, but suitable for hand-loading or tube-fed assembly. No power line protection is built in; this is a signal-rail or low-voltage bus clamp, not a mains-side suppressor.
Obsolete — sourcing through independent channels
Vishay lists the 1.5KE9.1HE3/73 as obsolete. No pin-compatible direct replacement from Vishay is documented, so a BOM that requires this exact clamping voltage and package should be sourced as a last-time-buy or cross-referenced to a functionally equivalent TVS from another supplier with a similar standoff and clamp envelope.