Transient suppressor for 42.6V rails in harsh environments
The 42.6V reverse standoff voltage makes it a fit for 36V or 48V nominal rails where transients from inductive loads or lightning-coupled surges need shunting before they reach downstream silicon. The SQ-MELF (B) package is a surface-mount ceramic barrel with solderable end caps — the same footprint as a standard MELF but square-bodied for pick-and-place alignment.
Minimum breakdown voltage is 53.2V, with the clamping ceiling at 77V. That 23.8V window between breakdown and clamp gives the designer room to place the TVS after a fuse or series resistor without the clamp voltage drifting into the protected load's absolute maximum rating. The 500W rating is the peak pulse power at 25°C for a 10/1000µs exponential waveform. Derate linearly above 25°C per the datasheet curve — at 175°C the derated capability drops to roughly 250W, so a 48V bus in a 125°C ambient needs a parallel second device or a higher-rated part.
Active production — no near-term obsolescence
The SQ-MELF package is a standard Microchip high-rel format shared across the 1N61xxAUS family, so the production line is stable and the tooling is mature.