Surge rating and protection window
The 1.5KE320CA is a 1500W bidirectional TVS diode from the Littelfuse 1.5KE series, designed to clamp transients on AC power lines or bipolar signal rails. Its 273V reverse standoff voltage lets it sit across a 240VAC line without conducting during normal operation; the 304V minimum breakdown triggers clamping, and the 441V clamping voltage at 3.5A (10/1000 µs pulse) limits the let-through energy into the downstream circuit. The bidirectional single-channel construction means the same device clamps positive and negative transients equally — no polarity marking needed during assembly, which reduces placement errors on high-density boards.
Thermal and mechanical fit
The DO-201AA axial-lead package (DO-27 equivalent) is a through-hole footprint that suits point-to-point wiring or PCB mounting with standard 0.100-inch lead spacing. Tape and reel packaging supports automated insertion for volume builds. For shorter pulses (8/20 µs, common in ESD testing), the peak power capability is higher; the datasheet's pulse-derating curve gives the multiplier for non-standard pulse widths.
The DO-201 package and bidirectional polarity make this a drop-in fit for existing layouts using the 1.5KE footprint.