What the 1500W peak pulse rating means for your protection design
The 1.5KE15ARL4G is a 1500 W peak-pulse-power Zener TVS diode from the Littelfuse Mosorb series, clamping at 21.2 V maximum on a 71 A, 10/1000 µs surge waveform. That 1500 W rating is the absolute-maximum non-repetitive pulse — the device absorbs the surge and clamps the voltage below the downstream circuit's breakdown threshold, but only if the pulse energy stays within the single-pulse derating curve.
Trigger threshold and standoff — where the TVS starts protecting
Reverse standoff voltage is 12.8 V typical, meaning the TVS draws negligible leakage below that rail voltage. Breakdown occurs at 14.3 V minimum, so on a 12 V bus the device stays out of the circuit until a transient pushes the line past 14.3 V — then it clamps hard at 21.2 V maximum. That 6.9 V window between standoff and clamp is the margin the protected load must survive.
Temperature range and deployment context
In a sealed enclosure or near a hot power supply, derate the peak pulse power above 25°C per the datasheet curve; at 175°C the 1500 W rating drops to approximately 150 W.
Obsolete — sourcing the 1.5KE15ARL4G today
Littelfuse lists the 1.5KE15ARL4G as obsolete.