What this 1.5 kW TransZorb covers on the automotive bus
The 1.5KE91HE3/73: It clamps a 73.7 V reverse standoff (the nominal operating voltage it leaves alone) to a maximum of 131 V at the 11.5 A peak pulse current (10/1000 µs waveform). The 1500 W peak pulse rating means it can absorb a single 10/1000 µs surge up to that power without failing — enough for load-dump or inductive kickback on a 48 V or 72 V nominal bus in an automotive ECU. Packaged in the DO-201AA (DO-27) axial-lead form, it is a through-hole part — the leads handle the surge current without the trace-width constraints of a surface-mount pad. The single unidirectional channel protects one rail per device.
Lifecycle reality — obsolete, but still sourceable
Vishay has marked the 1.5KE91HE3/73 as obsolete. The AEC-Q101 qualification means the parts in this lot were originally screened for automotive-grade reliability (temperature cycling, ESD, and PPAP documentation). If the design is locked to this Vishay part number, the qualification trace is intact as long as the supply chain provides genuine, un-reeled parts.