7.5 V Zener, 1 W, DO-41 axial
The 1N4737AP/TR12 is a 7.5 V Zener diode from Microchip Technology, rated for 1 W continuous power dissipation in the through-hole DO-204AL (DO-41) axial package. The ±5% tolerance on the nominal Zener voltage means the regulation point falls between 7.125 V and 7.875 V — tight enough for most reference and clamping duties in low-voltage analog rails.
Thermal and rework profile
The DO-41 axial body handles the full 1 W with adequate lead-length and copper trace area for heat sinking — the junction-to-ambient thermal path runs through the leads, so keep the lead length short and the solder pads generous on the PCB. The axial package reworks cleanly under hot air or soldering iron — the glass-passivated junction survives the thermal shock of desoldering, and the banded cathode mark is clearly visible for orientation.
Impedance and leakage at the operating point
Maximum Zener impedance is 4 Ohms at the test current — this sets the regulation slope: a 10 mA load swing shifts the output by only 40 mV, well within the ±5% tolerance band. Reverse leakage is specified at 10 µA maximum with 5 V applied across the junction — a useful sanity check for standby power budgets in battery-backed circuits. Forward voltage drop is 1.2 V maximum at 200 mA forward current — the diode conducts symmetrically if used as a bidirectional clamp, though the Zener region is the primary operating mode.
Supplied in Tape & Reel packaging (TR suffix) for automated pick-and-place assembly, though the through-hole DO-41 body is typically hand-inserted or wave-soldered — the reel format suits high-volume kitting.