7.5 V shunt regulation in a DO-41 axial package
The 1N4737APE3/TR8 is a 7.5 V zener diode from Microchip Technology's 1N4737 family, rated for 1 W continuous power dissipation in the standard DO-204AL (DO-41) axial-lead package. The 7.5 V nominal breakdown with ±5% tolerance means the actual zener voltage falls between 7.125 V and 7.875 V — tight enough for most shunt regulator and voltage reference applications where a precision reference is not required. With a maximum impedance of 4 Ohms at the zener point (Zzt), the diode maintains regulation within a few hundred millivolts as the load current varies — a 10 mA change in zener current shifts the voltage by roughly 40 mV. The 1 W power ceiling in the DO-41 body limits the steady-state zener current to about 133 mA at 7.5 V, though derating is required above 25°C ambient.
Temperature range and reverse leakage
Reverse leakage is specified at 10 µA maximum with 5 V reverse bias — a useful check for low-power standby circuits where the zener sits across a rail and must not drain the supply when the rail is below the breakdown voltage. Forward voltage at 200 mA is 1.2 V maximum — this matters if the diode is used in a bidirectional clamp configuration where forward conduction occurs during transient events. The tape-and-reel packaging (TR suffix) feeds directly into axial-lead insertion machines, making it suitable for high-volume through-hole assembly lines.