500 W Zener TVS in SQ-MELF B – what the ratings mean
The minimum breakdown voltage is 10.83 V, clamping at 17.75 V max at 28.12 A peak pulse current. That clamp ceiling tells you the highest voltage the protected node will see during a surge — if your downstream silicon is rated for 20 V absolute max, this part leaves 2.25 V of margin at the peak current. The junction temperature range spans -55°C to 175°C, so it can sit on a hot PCB near a power stage or in an outdoor enclosure without derating the breakdown threshold. The SQ-MELF B package is a surface-mount ceramic barrel — the same footprint as a standard MELF but with a square body that self-aligns during reflow.
Breakdown and clamp – the two numbers that size the protection
The reverse standoff voltage is 9.1 V typical — this is the DC bus voltage the diode will not conduct below. Once the transient pushes past 10.83 V (min breakdown), the device starts clamping. At the peak pulse current of 28.12 A, the clamp voltage reaches 17.75 V max. For a 12 V nominal rail, the 9.1 V standoff is comfortable; for a 5 V rail, the 17.75 V clamp may be too high and you would step down to a lower-voltage part in the same 1N61xx family.
Active production – no end-of-life notice on record
Microchip lists the 1N6108US/TR as Active with no PCN or last-time-buy window published. The Tape & Reel (TR) suffix indicates 16 mm tape, 7-inch reel — standard for automated pick-and-place. Sourced to order against BOM quantities; confirm current lead time and pricing at quote.