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. The -55°C to 175°C junction temperature range covers military and downhole applications where the ambient floor and self-heating stack up.
Clamping voltage and breakdown margin
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.