Surge-rated Zener TVS in a hermetic MELF
It clamps at 21V maximum while conducting 71.4A peak pulse current, protecting a 11.4V nominal rail. The ceramic MELF body handles the thermal shock of repetitive surges better than plastic SMD packages — important if this sits on a 12V bus in an avionics or industrial control board.
Clamping voltage and breakdown margin
Minimum breakdown voltage is 14.25V, giving a 2.85V guard band above the 11.4V standoff. That margin keeps the diode out of conduction during normal rail ripple while still firing before the downstream silicon sees damaging overvoltage. The 21V clamp at 71.4A is the worst-case let-through — your downstream capacitor or regulator must survive that peak for the pulse duration.
Active production — no obsolescence watch needed
Microchip lists the 1N6146AUS as Active. The SQ-MELF package is a standard Microchip TVS footprint, so supply continuity is stable. For BOM planning, the base product number is 1N6146 — the 'AUS' suffix denotes the surface-mount variant.
Hermetic MELF — rework and board-fit notes
The SQ-MELF, C package is a ceramic cylinder with wrap-around metallised terminations. It reflows well with standard solder paste — no fine-pitch alignment needed. The ceramic body absorbs less moisture than plastic, so no bake-out before reflow. Pin 1 orientation is marked by a band on the cathode end; the bidirectional version has no polarity, so orientation is irrelevant for the clamping function. The cylindrical shape can roll during pick-and-place if the vacuum nozzle isn't centred — confirm your feeder tape pocket holds it securely.