The 1.5KE91A/54: Its lifecycle status is Obsolete — the manufacturer no longer produces this exact order code, so any BOM line using it needs a sourcing plan through independent channels. The DO-201AA (DO-27) axial-lead package is a through-hole form factor that reworks cleanly under a hot-air station — the leads take solder well and the body markings are legible after removal, which matters for board repair and rework scenarios.
Key ratings and what drives the fit
The 77.8 V reverse standoff voltage (working voltage) means this diode will not conduct at normal rail levels up to that point — it sits across the line as a high-impedance shunt until a transient exceeds the breakdown threshold.
Sourcing an obsolete TVS diode
Since the 1.5KE91A/54 is marked Obsolete by Vishay, new-stock is sourced through independent surplus and broker channels — each lot is verified for authenticity and tested to the original datasheet parameters before shipment. No official successor order code is recorded on this line — a functional replacement would need to match the 77.8 V standoff, 1500 W pulse rating, and DO-201AA footprint, but no pin-compatible direct substitute is documented here.