Obsolete 1500 W TVS — what the ratings mean for a replacement search
The 1.5SMC13AT3G: Its 18.2 V clamping voltage at the 82 A peak-pulse current (10/1000 µs waveform) means it limits the overvoltage seen by downstream silicon to under 19 V — a figure that matters for a 12 V bus where the protected device's abs-max rating is typically 20-24 V. The 1500 W rating is the peak pulse power dissipation for a 10/1000 µs exponential waveform; derate this for shorter or longer pulses per the manufacturer's curve. For a 12 V automotive or industrial DC bus, the 11.1 V reverse standoff means the diode does not conduct at the nominal rail voltage, only above the 12.4 V minimum breakdown threshold.
Package and board-fit — DO-214AB SMC footprint
The DO-214AB (SMC) package is a standard surface-mount footprint for high-power TVS diodes. The part is unidirectional (single-channel Zener), so the cathode band on the body must align with the positive rail being protected. Operating temperature range is -65 °C to +150 °C junction, covering automotive under-hood and industrial enclosure environments. No power line protection (bidirectional) — this is strictly for unidirectional DC rail clamping.
Sourcing an obsolete part — the procurement reality
Littelfuse has marked the 1.5SMC13AT3G as obsolete.