7.5 V regulation with ±2% guard band
The 1N4737CP/TR12 is a 7.5 V Zener diode rated for 1 W continuous dissipation in the DO-41 axial package. The ±2% tolerance on Vz means the regulation window is 7.35 V to 7.65 V — tighter than the standard ±5% Zener, so a rail that needs 7.5 V ± 0.15 V stays in spec without a secondary trim.
Impedance and leakage — the load-line limits
Maximum Zener impedance is 4 Ohms at the test current — this sets the voltage drop for a given load current swing. A 5 mA change in load shifts the regulated voltage by 20 mV, within the ±2% band. Reverse leakage at 5 V is 10 µA max, negligible for most bias circuits but worth derating if the Zener sits across a high-impedance node at elevated temperature. Forward voltage is 1.2 V max at 200 mA — this is the conduction drop if the diode is forward-biased (e.g., in a reverse-polarity protection string).
1 W at 150°C — thermal budget
Rated for 1 W continuous power at 25°C ambient, derating to zero at 150°C junction. In a 70°C ambient with no forced air, the DO-41 body dissipates roughly 800 mW before the junction exceeds 125°C — the 7.5 V Zener at 100 mA draws 750 mW, leaving margin for a 50°C ambient rise. For higher currents, a heatsink clip on the DO-41 body or a Kelvin-connected cathode lead reduces the junction-to-ambient thermal resistance.
DO-41 axial — through-hole for manual or wave-solder
The DO-204AL (DO-41) axial-lead package is through-hole, compatible with hand-insertion, wave-solder, and tape-and-reel auto-insertion. The TR suffix indicates Tape & Reel packaging — 52 mm tape width, 5,000 pieces per reel, suitable for pick-and-place with axial feeders.