The 1.5KE27HE3/54: The 21.8 V standoff voltage means the diode draws negligible leakage below that rail — it sits across a 24 V nominal bus without loading it. When a transient exceeds the 24.3 V minimum breakdown voltage, the device clamps at 39.1 V maximum, shunting up to 38.4 A of surge current (10/1000 µs) to ground. The 1500 W peak pulse rating is the product of clamp voltage and peak current — it defines the energy the diode can absorb in a single surge event without failing. For repetitive transients, derate per the pulse derating curve in the full datasheet.
Lifecycle status and sourcing for the 1.5KE27HE3/54
Vishay lists the 1.5KE27HE3/54 as obsolete. For a BOM line that requires this exact AEC-Q101 qualification and 1500 W rating in a DO-201AA package, the 1.5KE27HE3/54 remains the specified fit.