What is SM30T6.8AY?
The SM30T6.8AY is a single-channel automotive-grade Zener diode from STMicroelectronics, designed for transient voltage suppression in harsh environments. It is AEC-Q101 qualified, rated for 3000W peak pulse power (10/1000µs waveform), and offers a breakdown voltage of 6.45V minimum with a clamping voltage of 9.2V at 327A peak pulse current.
The 6.45V minimum breakdown voltage sets the threshold where the diode starts conducting in avalanche. For a 5V nominal rail, this provides a guard band: the device stays off during normal operation but clamps fast when a transient exceeds the standoff. The 9.2V clamping voltage at 327A peak pulse current defines the maximum voltage the protected circuitry sees during a surge event — critical for selecting downstream components with sufficient voltage rating. The 3000W peak pulse power rating (10/1000µs) is the energy-handling capability for a single pulse; for repetitive surges, derating per the thermal curve is required.
Automotive qualification and temperature range
AEC-Q101 qualification means the SM30T6.8AY has passed the automotive stress tests for discrete semiconductors — including high-temperature reverse bias, temperature cycling, and surge robustness. This is a part you can specify for engine control units, transmission controllers, and battery-management systems without additional qualification overhead.
Package and mounting
Housed in a surface-mount package, the SM30T6.8AY is a standard footprint for power TVS diodes. The SMC package offers a larger body than the smaller SMA/SMB variants, which helps with thermal dissipation during pulse events.
Lifecycle and sourcing
For dual-sourcing resilience, the base product number SM30T6.8 covers the family; the 'AY' suffix denotes the automotive grade and specific packaging variant.