12 V regulation with a 1 W thermal budget
The 1N4742UR-1/TR is a 12 V Zener diode in the Microchip Technology portfolio, rated for 1 W continuous power dissipation in a DO-213AB MELF glass package. The 9 Ohm maximum impedance (Zzt) at the test current keeps the regulation slope shallow; as the bias current varies, the output voltage shifts less than it would with a higher-impedance part. Reverse leakage is specified at 5 µA maximum when the applied voltage is 9.1 V — well below the Zener knee, so this is the standby current in a shunt regulator or protection clamp.
The glass MELF body (DO-213AB) is hermetic — no moisture ingress, no plastic package cracking during reflow. Surface-mount assembly uses standard pick-and-place; the cylindrical body rolls during placement if the nozzle vacuum is too low, so a flat-tip or cavity nozzle is recommended.
Active lifecycle and sourcing
No pin-compatible alternative is recorded on this line; the DO-213AB footprint is specific to this hermetic MELF series.