Zener regulation at 6.2 V, 500 mW, in a hermetic MELF
The 1N6319US/TR is a 6.2 V Zener diode rated for 500 mW continuous power dissipation, housed in a surface-mount SQ-MELF B package — a hermetic, glass-passivated ceramic body that handles the -65°C to 175°C junction temperature range without moisture ingress. Maximum Zener impedance is 3 Ohms at the test current, and reverse leakage is held to 5 µA at 3.5 V — both figures that tell you the regulation knee is tight enough for a 6.2 V rail that needs to stay within ±5% over temperature.
Hermetic MELF package for harsh environments
The SQ-MELF B (also called a DO-213AB outline) is a cylindrical, end-capped ceramic package with metallized bands — it is inherently hermetic and survives thermal cycling from -65°C to 175°C, making it a common choice for avionics, downhole instrumentation, and military-grade power supplies where a plastic SMD package would delaminate. Supplied on Tape & Reel for pick-and-place assembly; the cylindrical body needs a flat solder-paste deposit on the board to avoid tombstoning during reflow.
No direct pin-compatible second source is listed on the manufacturer's cross-reference; the SQ-MELF B footprint is specific to hermetic Zener diodes, so a board-level substitution would require a package change.