TransZorb TVS, 1500 W bidirectional clamp
The 1.5KE91CA-E3/54: This is a Zener-type TVS in the DO-201AA (DO-27) axial-lead package, through-hole mounted, intended for general-purpose transient suppression on DC rails and signal lines that see bidirectional overvoltage events.
Clamp voltage and breakdown margin
The minimum breakdown voltage is 86.5 V, giving a 8.7 V margin above the 77.8 V standoff — the diode stays high-impedance under normal rail voltage and only conducts when the transient pushes past the breakdown knee. At the rated 12 A peak pulse current the clamp holds at 125 V maximum, which means a 48 V rail riding at 77.8 V sees the transient clipped to 125 V before the downstream silicon reaches its abs-max rating.
Sourcing and lifecycle posture
For a second-source hedge, parametric equivalents in the same DO-201AA package with matching standoff and peak power can be evaluated at quote time.