The 1.5KE11AG is a unidirectional Zener TVS diode from onsemi's Mosorb™ series, rated for 1500W peak pulse power (10/1000 µs waveform). It clamps transients at 15.6V maximum when the surge current hits 96A, making it a fit for general-purpose overvoltage protection on DC power rails, relay coils, and signal lines in industrial or automotive environments. The 10.5V minimum breakdown voltage and 9.4V reverse standoff mean it starts conducting just above a 9V rail, so it suits 12V systems where the nominal bus is 12V but transients can spike well above.
Peak pulse power and clamping under surge
At 1500W peak pulse power, the 1.5KE11AG can absorb a 96A surge (10/1000 µs) before the junction temperature climbs past the rated limit. That 96A figure is the current at which the clamping voltage hits 15.6V — so the energy is 1500W for that pulse width, and the device survives it repeatedly if the duty cycle stays low. The DO-201AD axial package is a through-hole part with a 0.052-inch diameter lead, which handles the thermal pulse by conducting heat into the PCB traces. No power line protection feature — it's a standalone TVS, not a crowbar or integrated filter.
Obsolete status and sourcing reality
onsemi lists the 1.5KE11AG as Obsolete. That means no ongoing production; the only supply is existing stock on distributor shelves or the surplus market. The base product number is 1.5KE, so a functional replacement would be another 1.5KE-series TVS with the same breakdown voltage (10.5V min) and package (DO-201AD) — for example, a 1.5KE11A from another brand, but confirm the clamping voltage and peak current match your design margin.