The STMicroelectronics 1.5KE300ARL is a unidirectional Zener-based transient-voltage-suppression (TVS) diode from the 1.5KE / TRANSIL™ series. It is designed to clamp fast-rising voltage transients on power rails, signal lines, and DC buses in general-purpose industrial, telecom, and consumer equipment. The part is rated for 1500W peak pulse power (1.5kW) at the standard 10/1000µs waveform, with a reverse standoff voltage of 256V and a maximum clamping voltage of 529V at the rated peak pulse current of 19A (8/20µs waveform).
The 1500W peak pulse power rating tells you the diode can absorb a 1.5kW surge for a 10/1000µs double-exponential waveform without failing. The 529V clamp voltage at 19A (8/20µs) is the worst-case voltage the protected rail will see during the transient — ensure downstream components have a voltage rating above this clamp level. Capacitance is 500pF at 1MHz, typical for a 1.5kW-class TVS at this voltage. On a high-speed data line this capacitance will load the signal; for 50/60Hz power or slow DC protection it is irrelevant.
Package, mounting, and lifecycle
The 1.5KE300ARL comes in a DO-201AA (DO-27) axial-lead through-hole package. The leads are tin-plated copper; the body is molded epoxy. Through-hole mounting is straightforward — the axial leads insert into plated through-holes and are wave-soldered or hand-soldered. The part is rated for general-purpose environments; no AEC-Q automotive qualification is listed, so it is suited for industrial and commercial applications rather than under-hood automotive.