5.6 V Zener regulation at 1 W dissipation
The 1N4734AP/TR12 is a 5.6 V Zener diode from Microchip Technology in the standard DO-204AL (DO-41) axial-leaded package. It dissipates 1 W continuously, so the junction temperature rise at full rated power in still air is the limiting factor for derating — a 1 W part in a DO-41 body needs adequate lead length or a heatsink tab if operated near the ceiling in a 70 °C ambient. The ±5% tolerance on the nominal 5.6 V Zener voltage means the actual regulation point for any given unit falls between 5.32 V and 5.88 V at the test current. For a rail that must stay within 5% of 5.6 V, a tighter-binned part or a series resistor adjustment is needed.
Impedance and leakage — the so-what for the bench
Maximum Zener impedance is 5 Ohms at the Zener test current. This dynamic resistance means the output voltage shifts about 5 mV per mA of load change — negligible for a simple shunt regulator but relevant if the diode also serves as a reference for a downstream converter. Reverse leakage is 10 µA max at 2 V reverse bias, well below the Zener knee. At the 5.6 V operating point leakage rises, but the 1 W power rating ensures the diode stays in the avalanche region without thermal runaway under normal bias. Forward voltage is 1.2 V max at 200 mA — the diode conducts as a standard rectifier in the forward quadrant, though the 1 W dissipation limit applies in either direction.
Temperature range and soldering margin
The DO-41 body with tin-plated copper leads withstands wave-solder profiles up to 260 °C peak for 10 seconds without compromising the die attach.
Microchip Technology lists this part as Active. The base product number is 1N4734, and the /TR12 suffix denotes Tape & Reel packaging for automated insertion.