The STMicroelectronics SM15T33CAY is a bidirectional Zener TVS diode from the SM15TY TRANSIL™ series, rated for 1500 W peak pulse power over the standard 10/1000 µs waveform. That 1.5 kW rating means it can absorb the energy from a load dump or a direct inductive kick without the junction failing — a common requirement on 24 V automotive buses where the nominal rail sits at 28.2 V reverse standoff.
AEC-Q101 and 150°C junction — where it goes
That puts it squarely in under-hood and engine-bay applications — think transmission control modules, ABS pumps, or battery-management systems where ambient under the hood can hit 125°C and the junction sees the spike. The SMC (DO-214AB) package is a surface-mount footprint that handles the 1500 W pulse without needing a heatsink, provided the PCB copper area is adequate for thermal spreading.
Bidirectional, single-channel — layout note
It is a single bidirectional channel, so one device clamps both polarities on a signal or power line. The 169 A peak pulse current (8/20 µs waveform) covers direct ESD strikes and fast transients; the 10/1000 µs waveform rating is the one to use for surge coordination.