Obsolete — last-time-buy sourcing
The 1.5KE9.1ARL4G is listed as Obsolete by Littelfuse, meaning the manufacturer has ended production. Available through independent distribution channels; quantities are confirmed at RFQ. This is a surplus/broker sourcing path — each lot is traceable and verified against the original Littelfuse specifications.
What the ratings mean for your protection design
Reverse standoff voltage of 7.78V means the diode is effectively invisible to the circuit below that DC level, drawing negligible leakage. Breakdown occurs at 8.65V minimum, triggering the clamping action. Unidirectional, single-channel Zener — the cathode band on the DO-201AD body must be oriented toward the positive rail.
DO-201AD axial leaded package — the body diameter is 5.3 mm typical, with 0.96 mm diameter leads. Through-hole mounting; the lead spacing on a standard PCB footprint is 10.2 mm. The axial form factor allows hand-insertion or wave-solder assembly. Available in Tape & Reel (TR) or Cut Tape (CT) packaging options — the TR variant is suited for automated insertion; CT is preferred for prototype or low-volume builds.