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. The product status is listed as Active, so there is no current obsolescence or last-time-buy notice.