6.8 V zener with military pedigree
The JANTXV1N4461US/TR is a 6.8 V zener diode in a surface-mount SQ-MELF (D-5A) package, rated for 1.5 W continuous power dissipation. It carries full MIL-PRF-19500/406 qualification, which means every unit is screened to the military specification for hermetic glass packages — not a commercial-grade part with a military marking. The ±5% tolerance on the 6.8 V nominal zener voltage gives a tight regulation window for reference or clamping circuits in avionics, satellite power supplies, and downhole instrumentation where the operating temperature spans -65°C to 175°C.
What the 1.5 W rating means for your design
At 1.5 W maximum power, this zener can handle steady-state dissipation that would overstress a 500 mW device. For a 6.8 V nominal zener, 1.5 W translates to about 220 mA continuous zener current — but that's at 25°C lead temperature. At 175°C junction, derate to roughly 30% of that figure. The SQ-MELF package's glass body conducts heat primarily through the end caps; a thermal via stitch under each cap on the PCB pulls heat into the ground plane. Without that, the junction temperature rises faster than the 2.5 Ω maximum dynamic impedance suggests.
It is a current-production military-qualified device, not a last-time-buy or obsolete line.