Parametrics that drive the fit check
The SMAJ4729CE3/TR13: Rated to dissipate 2 W continuously (Power - Max) — this sets the DC load ceiling; in a shunt regulator or voltage clamp, the junction-to-ambient thermal path in the SMA footprint governs how much of that 2 W is usable at 85°C ambient. The ±2% tolerance (±72 mV at 3.6 V) is tight enough for a precision reference rail feeding a comparator or ADC bias, but the 10 Ohm maximum Zzt (Zener impedance) means the output voltage shifts with current — the effective regulation is a function of the Zener current, not just the nominal Vz. Reverse leakage is specified at 100 µA max at 1 V reverse bias — well below the self-discharge threshold of most battery-backed rails, so it won't drain a coin cell in storage.
Temperature grade and board integration
The DO-214AC (SMA) package is a standard footprint; reflow profile follows JEDEC MSL-1 (no bake required before assembly) as typical for Microchip Zener diodes in this family. The Tape & Reel (TR) packaging is the production-friendly format for pick-and-place.