Zener TVS in a DO-201AD axial package
The 1.5KE9.1AG is a unidirectional Zener TVS diode from onsemi's Mosorb™ series, rated for 1500 W peak pulse power at 10/1000 µs. It clamps transients at 13.4 V maximum while conducting 112 A peak pulse current. The 7.78 V reverse standoff voltage means it sits across a 5 V or 6 V rail without conducting during normal operation, only firing when a surge pushes the line above the 8.65 V minimum breakdown threshold.
Lifecycle status — obsolete, plan the replacement
onsemi has marked the 1.5KE9.1AG as Obsolete. That means no ongoing production, no last-time-buy window — the part is already off the manufacturing line. For a BOM line that still needs this protection level, the practical move is to source existing inventory or evaluate a direct replacement within the 1.5KE family (same package, same 1500 W rating) with a matching breakdown voltage.
Sourcing reality for an obsolete TVS
Because the 1.5KE9.1AG is obsolete, the only supply channel is existing stock — franchised or independent. A cross to a sibling with the same standoff and breakdown voltage is the cleanest path. Sourced per RFQ against your BOM quantity.