5.1 V regulation point and 1 W power budget
The 1N4733AURE3/TR is a 5.1 V zener diode in the 1N4733A family from Microchip Technology, rated for 1 W continuous power dissipation in a surface-mount DO-213AB MELF glass package. With a ±5% tolerance on the nominal 5.1 V zener voltage, the regulation window spans 4.845 V to 5.355 V — tight enough for most 5 V rail clamping or reference applications where a precision shunt regulator is not required. The 1 W power rating sets the thermal ceiling: at 5.1 V the diode can sink roughly 196 mA continuous before exceeding the dissipation limit, assuming adequate board-level heat sinking through the MELF end-cap terminations.
Package and temperature grade
The glass body provides hermetic sealing, making it suitable for environments where moisture resistance is a concern. Rated for operation from -65°C to 175°C, this diode covers the full military temperature range. The wide span suits designs that must hold regulation across extreme thermal cycling, such as avionics or down-hole instrumentation.
Dynamic impedance and leakage
Maximum zener impedance is 7 Ohms at the test current — a relatively low dynamic resistance for a 5.1 V part, which means the voltage stays within the ±5% band under moderate load steps. Reverse leakage is specified at 10 µA maximum at 1 V reverse bias, confirming the diode blocks cleanly below the zener knee. Forward voltage is 1.2 V maximum at 200 mA forward current — a standard silicon diode drop, useful if the part is ever biased in the forward direction for polarity protection or clamping.