The 1.5SMC400AHM3_A/I is a 1500W (1.5kW) Zener TVS diode from Vishay's automotive-grade 1.5SMC TransZorb series, rated for a 342V reverse standoff voltage. AEC-Q101 qualification means this part has passed the automotive stress tests — temperature cycling, high-temperature reverse bias, and ESD robustness — making it suitable for under-hood electronics, battery management systems, and 48V mild-hybrid bus protection where reliability over a 15-year service life is non-negotiable.
Clamping voltage and the protection margin
The 342V reverse standoff (working voltage) is the maximum continuous DC or peak AC voltage the TVS can sit across without conducting appreciably. The minimum breakdown voltage is 380V, giving a 38V guard band before avalanche begins. At the rated 2.7A peak pulse current, the clamp voltage reaches 548V — the downstream equipment must survive that peak without damage. At the high end, the clamp voltage rises slightly; derate the peak pulse power above 25°C per the datasheet's thermal profile.
The base product number 1.5SMC400 covers the full voltage variant range; the suffix AHM3_A/I denotes the AEC-Q101 automotive grade and the specific lead-free plating finish.