500W Zener TVS in a Hermetic SQ-MELF Package
The 1N6122AUS: It clamps at 64.6V max from a 35.8V reverse standoff, with a minimum breakdown of 44.7V. That puts it on a 28V or 36V rail — the clamp voltage stays under 65V, which keeps downstream silicon safe during a surge. The SQ-MELF B package is a hermetic ceramic body with metallized end caps — no plastic molding. That matters for high-humidity or outgassing-sensitive environments, and it survives rework cycles under hot air better than a plastic SMC because the ceramic doesn't soften. The B suffix means the base part number 1N6122 is screened to the JAN drawing; the AUS variant adds the surface-mount MELF termination.
Temperature Range and Junction Rating
At 175°C the leakage current rises, but the clamping voltage holds. For a 500W pulse at 25°C, derate linearly above 25°C per the datasheet curve; at 175°C the peak pulse power drops to roughly 20% of the 500W rating. If the board lives in a 125°C engine bay, budget the derated surge capacity.
Active Production – No EOL Risk
Microchip lists the 1N6122AUS as Active. That means the part is still in wafer fab and assembly; lead times are quoted per RFQ against the BOM quantity. The SQ-MELF package is a standard Microchip hermetic line — not a niche package that gets discontinued early.