The 1.5KE15AHE3/51: It clamps transients at 21.2 V max, with a 12.8 V reverse standoff and a 14.3 V minimum breakdown voltage. This part is AEC-Q101 qualified for automotive applications, meaning it has passed the reliability stress tests and temperature cycling required for under-hood and chassis-mounted electronics.
Clamping voltage and peak current — the real protection envelope
At the 70.8 A peak pulse current (10/1000 µs), the clamping voltage holds at 21.2 V max — this is the voltage the downstream circuitry sees during a surge. A 12 V rail with a 15% tolerance (13.8 V max) has 7.4 V of headroom before the TVS clamps, which keeps the protected device within its absolute maximum ratings. The 14.3 V minimum breakdown voltage ensures the TVS does not conduct at the nominal 12.8 V standoff, so it draws no leakage current under normal operating conditions. Power line protection is not supported — this is a unidirectional device for DC rail clamping, not for AC mains or bidirectional signal lines.
Obsolete — sourcing through independent channels
Vishay has marked the 1.5KE15AHE3/51 as obsolete. For existing BOM lines, this part is available through independent surplus and broker channels.