1500W peak pulse in a DO-201 axial can
The 1.5KE15H is a 1500W Zener TVS diode from Taiwan Semiconductor's 1.5KE series, packaged in a DO-201AA (DO-27) axial-lead through-hole can. It clamps a 12.1V reverse standoff rail to 22V maximum at a peak pulse current of 71A (10/1000µs waveform).
What the clamping numbers mean on a 12V rail
The 12.1V reverse standoff is the maximum DC voltage the diode will not conduct at — a 12V nominal battery bus or a 12V regulated supply sits below this threshold, so the TVS stays off in normal operation. The 1500W peak pulse rating (10/1000µs) defines the energy the part can absorb in a single transient — a 24V automotive load-dump pulse or an ISO 7637-2 test pulse 5a at this energy level will be clamped without the diode failing short.