500W bidirectional Zener TVS in a hermetic SQ-MELF
The 1N6112US is a 500W peak pulse power Zener TVS diode from Microchip Technology, configured as a single bidirectional channel. It clamps transients at 26.36V maximum with a 13.7V reverse standoff voltage, making it a direct fit for protecting 12V–15V rails in harsh environments. The SQ-MELF B package is a hermetic surface-mount ceramic body rated for -55°C to 175°C junction temperature — suited to avionics, downhole, and military power buses where plastic-packaged TVS devices would degrade.
Breakdown, clamping, and standoff — the protection window
The 1N6112US has a minimum breakdown voltage of 16.25V, a reverse standoff of 13.7V, and a maximum clamping voltage of 26.36V at the 18.91A peak pulse current (10/1000 µs waveform). The 2.55V gap between standoff and breakdown means the rail sees no leakage at nominal voltage, and the clamping ceiling stays below the typical 28V absolute-max of common 15V-rated ASICs. Bidirectional construction (single channel) eliminates polarity marking on the PCB — the device clamps equally in both directions, which simplifies layout for AC-coupled or floating signal lines.
Active production — no end-of-life watch needed
Microchip lists the 1N6112US as Active. The SQ-MELF package is a hermetic ceramic construction, not a plastic-molded body. This means the part has no moisture sensitivity level (MSL) rating — no bake-out required before reflow, and no floor-life clock to track.
Package and footprint — SQ-MELF B
The 1N6112US comes in the SQ-MELF B (also called B, SQ-MELF) package — a hermetic surface-mount ceramic barrel with solderable end caps. The footprint is the same as the industry-standard DO-213AB (MELF) outline; the PCB land pattern matches the standard MELF footprint for a 2-terminal axial-style body. The supplier device package is listed as B, SQ-MELF. The package is — not tape-and-reel — so plan for manual or tube-fed placement. Confirm the pick-and-place feeder compatibility if using automated assembly.