7.5 V regulation, 1 W dissipation, DO-41 axial body
The 1N4737E3/TR13 is a 7.5 V Zener diode rated for 1 W continuous power dissipation in the standard DO-204AL (DO-41) axial-leaded package. The ±10% tolerance on Vz means the actual breakdown voltage falls between 6.75 V and 8.25 V — tight enough for most rail-clamp and reference applications where a precision shunt reference isn't justified. Maximum Zener impedance is 4 Ohms (Zzt at the test current), which keeps the voltage shift under load moderate for a 1 W part. Reverse leakage is specified at 10 µA max with 5 V across the junction — a useful sanity check when the diode is used as a low-leakage clamp below its breakdown knee.
Board-fit and assembly with tape and reel
The DO-41 glass body measures about 5.2 mm long by 2.7 mm diameter with 25 mm (1-inch) axial leads — a through-hole footprint that has been a staple since the early days of PCB assembly. The tape-and-reel packaging (TR suffix) feeds into automatic insertion machines or hand-stuff stations; the reel quantity is typically 5000 pieces for this body size. Forward voltage is 1.2 V max at 200 mA if the diode is accidentally forward-biased — a detail that matters when the part is used as a back-to-back clamp and the forward leg carries current.
Microchip Technology lists the 1N4737E3/TR13 as Active.