The SMCJ40AE3/TR13 is a unidirectional Zener TVS diode rated for 1500W peak pulse power (10/1000µs waveform). It clamps transients on a single DC rail up to 40V reverse standoff, with a breakdown voltage minimum of 44.4V and a clamping ceiling of 64.5V at 23.2A peak pulse current. That 1500W rating is the energy it can absorb in a single pulse — enough for industrial surge protection on 24V or 36V supplies, telecom line cards, or automotive load-dump clamping where the transient energy is high but short. The part is marked with the cathode band, so orientation on the board is unambiguous even without a magnifier.
Temperature range and field reliability
The wide range means this part holds its clamping voltage across outdoor telecom cabinets, engine-bay electronics, and downhole instrumentation without derating the peak pulse power at the low end.