Obsolete, but still spec'd into BOMs — the sourcing reality
Vishay has marked the 1.5KE9.1CHE3/54 as Obsolete. That means the factory line is closed — no last-time-buy window, no further production. For a BOM that already carries this Vishay TransZorb, the only supply path is through independent distribution holding new-old-stock or surplus inventory. If you are migrating a design, the replacement will be a parametric match (same 1500 W peak pulse, same 7.37 V reverse standoff, same DO-201AA footprint) from the current TransZorb or an equivalent series — but no pin-compatible drop-in is formally listed.
1500 W peak pulse, 7.37 V standoff — what these ratings mean for the circuit
The 1.5KE9.1CHE3/54 is a 1500 W peak-pulse-power Zener TVS in the TransZorb series. The 7.37 V reverse standoff voltage means the diode will not conduct at normal 5 V or 12 V rails — it sits transparent across the line until a transient exceeds that threshold. Breakdown starts at 8.19 V min, and the clamping voltage is held to 13.8 V max at the full 109 A peak-pulse current. The 10/1000 µs waveform is the standard TVS test pulse — a 10 µs rise to peak, 1000 µs half-decay. The 109 A rating at that pulse shape tells you the diode can absorb a substantial surge without failing short. For a 12 V automotive battery line, the 7.37 V standoff gives a few volts of headroom before the diode starts clamping, which is typical for protecting downstream ECUs from load-dump and inductive-kick transients.
AEC-Q101 and the automotive deployment envelope
The 1.5KE9.1CHE3/54 carries the Automotive, AEC-Q101 qualification. AEC-Q101 is the stress-test and reliability standard for discrete semiconductors used in automotive electronics — it certifies the part for the temperature, vibration, and lifetime requirements of under-hood and cabin modules.