Clamping a 15.3V rail
The 1.5SMC18A-E3/57T: When the voltage across it exceeds the 17.1V minimum breakdown threshold, it shunts the surge to ground, holding the clamp at 25.2V maximum while passing up to 59.5A of the 10/1000µs waveform. The 1500W peak pulse rating means it absorbs a single 1ms surge without failing — the sort of hit a 24V industrial supply sees when a motor drive decelerates or a field wiring fault dumps energy back into the bus.
Package and board-fit
Housed in the standard DO-214AB (SMC) package, the same footprint as the SMCJ series. The surface-mount body suits reflow assembly; the wide leads carry the surge current without lifting the pad. Operating temperature spans -65°C to 150°C junction, so it survives the thermal cycling of an outdoor enclosure or an engine bay. The unidirectional polarity means it clamps positive transients only; for bipolar rails you need the bidirectional variant.
It remains a standard catalog item in the TransZorb family, so BOM planning doesn't need a substitution roadmap.