4.7 V Zener — the regulation point and what it drives
The SMAJ4732AE3/TR13 is a 4.7 V Zener diode in Microchip's SMAJ47xx family, rated for 2 W continuous power dissipation in the DO-214AC (SMA) surface-mount package. The 4.7 V nominal voltage with ±5% tolerance means the regulation window spans 4.465 V to 4.935 V — tight enough to clamp a 5 V rail or serve as a voltage reference in a bias supply. Maximum impedance (Zzt) is 8 Ohms at the test current. For a load drawing 50 mA, the voltage drop across the Zzt adds 0.4 V to the regulation error — this is the number to plug into the line-and-load regulation budget when the diode is used as a shunt reference. The 2 W power rating derates above 25°C ambient — at 85°C the allowable dissipation drops to roughly 1.2 W, so the load current must stay below 255 mA at the Zener voltage to stay inside the thermal envelope.
DO-214AC footprint and assembly fit
The DO-214AC (SMA) package is a standard JEDEC outline for 2 W Zener diodes. The cathode band identifies the marked terminal; the anode is the opposite end. Reflow profile follows J-STD-020 for MSL 1 parts — no bake required before assembly if the moisture barrier bag is intact. Supplied on Tape & Reel (TR), the SMAJ4732AE3/TR13 is ready for automated pick-and-place. The 8 mm tape width and 4 mm pitch are standard for SMA diodes, so no feeder changeover is needed if your line already runs DO-214AC parts.