3000 W automotive TVS for load-dump and surge protection
The STMicroelectronics SM30T30AY is a unidirectional TRANSIL™ TVS diode in the SM30TY series, designed to clamp voltage transients on automotive power rails. It delivers 3000 W peak pulse power per the 10/1000 µs waveform, with a reverse standoff voltage of 26 V and a maximum clamping voltage of 42.1 V at the rated peak pulse current of 71.3 A.
What the 3 kW rating means for the BOM
The 3000 W peak pulse power rating is the part's headline spec — it defines how much transient energy the diode can absorb before failing. For a 12 V automotive system, a 26 V standoff means the diode stays out of conduction during normal battery voltage (up to ~16 V during cold-crank), then clamps hard at 42.1 V to protect downstream regulators and ECUs. The 71.3 A peak pulse current at the clamping voltage gives you the headroom to calculate whether the diode can handle the worst-case surge from a 60 V load-dump event without exceeding its thermal limit. In practice, the 3 kW rating covers most passenger-car load-dump requirements per ISO 7637-2 pulse 5a, but verify the pulse energy against your specific alternator and battery configuration.
AEC-Q101 and the automotive supply chain
The SM30T30AY carries AEC-Q101 qualification, meaning it has passed the automotive-grade stress tests (high-temperature reverse bias, temperature cycling, autoclave, etc.) required for Tier-1 ECU programs. The base product number is SM30T30, indicating a family of voltage-variant parts sharing the same die and package; the 'AY' suffix denotes the specific breakdown and clamping voltage bin.
Package and mounting: DO-214AB SMC
The SM30T30AY is supplied in a DO-214AB (SMC) package, a standard surface-mount footprint for medium-power TVS diodes. The SMC body handles the 3 kW pulse without requiring a heatsink, relying on the PCB copper area for thermal dissipation. The package is compatible with standard pick-and-place equipment and reflow profiles used for automotive PCBA.