3.6 V shunt regulation in a hermetic MELF
The 1N6313US/TR is a 3.6 V Zener diode from Microchip Technology, rated for 500 mW continuous power dissipation in the SQ-MELF B package. The ±5% tolerance on the nominal voltage is standard for general-purpose shunt regulation — enough to clamp a 3.3 V rail or provide a reference for a comparator threshold without tight post-trim. Maximum impedance is 25 Ohms (Zzt), which governs how much the regulation voltage shifts with current through the device. At 3.6 V and 500 mW, the maximum steady-state current is about 139 mA — the impedance contributes roughly 3.5 mV of regulation drop per mA of load change.
Temperature range and package choice
The SQ-MELF B package is a hermetic surface-mount ceramic body with metallized end caps — it handles thermal cycling and moisture ingress better than plastic SMD packages, making it a fit for avionics, downhole instrumentation, or sealed modules where reliability under temperature stress is critical. Surface-mount assembly with tape-and-reel packaging (Cut Tape also available) — the SQ-MELF footprint is non-standard compared to SOD-123 or SOT-23; confirm the pad geometry against the package drawing before committing the PCB layout.