What the AEC-Q101 grade means for the BOM
The 1.5KE18CAHE3/51 is an automotive-grade TransZorb TVS diode from Vishay, qualified to AEC-Q101 — the stress and reliability screening that certifies it for under-hood and chassis-mounted electronics where temperature swings and transients are routine.
Obsolete — sourcing path for sustainment
Vishay has marked the 1.5KE18CAHE3/51 as obsolete. For a sustainment program that already has this part in the BOM, the DO-201AA axial package and 15.3 V reverse standoff voltage define the form-fit-function envelope — any substitute must match the 1.5 kW pulse capability and the bidirectional clamping characteristic.
Key ratings and the fit decision
The breakdown voltage range starts at 17.1 V minimum, so the diode begins conducting before the protected rail exceeds the typical 24 V load-dump ceiling in automotive 12 V systems. The single bidirectional channel handles both positive and negative transients on the same line, eliminating the need for two unidirectional devices in antiparallel.