15 V regulation with ±2% precision
The 1N4744CPE3/TR8 is a 15 V zener diode rated for 1 W continuous power dissipation in the DO-204AL (DO-41) axial-lead package. The ±2% tolerance on the nominal voltage means this part holds the regulation point tighter than the standard 5% grade — relevant when the zener serves as a shunt reference for an ADC supply or a bias rail where a few hundred millivolts of drift affects circuit accuracy. Maximum zener impedance is 14 Ohms at the test current. Lower impedance means the voltage stays flatter across the operating current range — a 14 Ohm Zzt is typical for a 1 W, 15 V part and keeps the regulation within the tolerance band over the full rated current swing. Reverse leakage is specified at 5 µA maximum with 11.4 V applied across the junction — that is 76% of the nominal zener voltage. For a bias network or a bleeder circuit, this leakage floor tells you how much current the zener draws before it enters breakdown; below that voltage the part is essentially an open circuit.
Temperature range and board fit
The 1 W power rating assumes the leads are soldered into a standard FR-4 board with adequate copper area to sink heat; in free air without a heatsink the derating curve applies above 50°C ambient. Forward voltage is 1.2 V maximum at 200 mA — this is the conduction drop when the diode is forward-biased, not the zener region. It matters if the part sees a forward surge during power-up or reverse-polarity events; the 1.2 V drop at 200 mA is well within the 1 W dissipation budget for short-duration transients.
Active lifecycle — sourcing posture
The Tape & Reel (TR) packaging option supports automated through-hole insertion — the axial leads are taped on reel for pick-and-place or radial-insertion machines, reducing manual handling cost in volume assembly.