1500 W peak pulse — the clamping envelope that protects the rail
The 1.5KE39BULK: That 1500 W rating means the device can absorb a transient up to 26.5 A peak pulse current before the clamping voltage hits 56.4 V maximum — the rail it protects sees no more than that ceiling during the surge event. The reverse standoff voltage of 31.6 V typical sets the DC operating bias: the diode stays high-impedance below that level, so a 24 V or 28 V supply rail runs undisturbed in normal operation. Breakdown starts at a minimum of 35.1 V, giving a narrow guard band between the working rail and the avalanche threshold.
DO-201 axial — through-hole for high-surge board positions
Packaged in a DO-201AA (DO-27) axial-lead through-hole body, the 1.5KE39BULK mounts into a 1.1 mm diameter hole on a standard PCB or terminal strip. The axial leads carry the full surge current without trace neck-down — the limiting factor is the copper pad area and the solder fillet, not the lead itself. Operating temperature spans -65°C to 175°C junction, covering the full industrial and automotive under-hood range. No power line protection feature is built in — this is a stand-alone transient suppressor, not a crowbar or a polyfuse.