The STMicroelectronics SM30T26AY is a unidirectional TRANSIL™ TVS diode from the automotive SM30TY series, qualified to AEC-Q101. It clamps transients on a 22V nominal rail, with a minimum breakdown of 24.4V and a maximum clamping voltage of 35.5V when the peak pulse current hits 84.5A under the 10/1000µs waveform. The 3000W peak pulse power rating tells you the device can absorb a single 3kW surge without failing — that is the number that decides whether the diode survives a load-dump or alternator-field decay event on a 12V or 24V automotive bus.
Package and footprint — DO-214AB (SMC)
The SM30T26AY is supplied in a DO-214AB (SMC) surface-mount package. This is a standard footprint for automotive TVS diodes in the 3kW class, so the board layout can often reuse an existing SMC pad pattern. The package is rated for surface-mount assembly only; no through-hole variant exists in this series.
Automotive qualification and lifecycle
The series is explicitly labelled for automotive applications.