1N3318RB

Overview

The Microchip Technology 1N3318RB is a high-power 50 W Zener diode from the 1N3305 through 1N3350B series. It provides voltage regulation with a nominal Zener voltage of 19 V at a test current of 660 mA. The device features a maximum dynamic impedance of 2.2 ohms and a maximum reverse current of 10 µA. It operates within a junction temperature range of -65°C to +175°C and dissipates up to 50 watts at a case temperature below 75°C. The component utilizes a DO-5 (DO-203AB) package with an 11/16 inch hexagonal stud.

Feature Summary

• Hermetically sealed welded construction with internal solder bond
• Reverse polarity configuration with cathode connected to the case
• Inherently radiation hard design
• Non-sensitive to electrostatic discharge

Applications

• High power voltage regulation
• Overvoltage protection circuits
• Reference voltage generation in harsh environments

Procurement Notes

Verify that the specific part number includes the 'R' suffix to confirm the reversed polarity configuration where the cathode is connected to the case, as standard units feature an anode-to-case connection. Confirm the 'B' suffix indicates the required 5% tolerance on the Zener voltage. Ensure the procurement documentation references the correct JEDEC registration for the 1N3318B type to validate electrical characteristics against the official datasheet specifications.

Selection Notes

Select this component when a robust 50 W voltage regulator is required for applications demanding high thermal stability and radiation hardness. The reversed polarity option is suitable for designs requiring the cathode to be electrically tied to the mounting chassis or heat sink. Verify that the application can accommodate the DO-5 stud mount package and provide adequate heat sinking to maintain the case temperature below 75°C for full power dissipation.

Part Context

This device belongs to the Microsemi Scottsdale Division 1N3305 through 1N3350B series of 50 Watt Zener diodes. These components are designed for high-power applications and are also available in JAN, JANTX, and JANTXV military qualifications per MIL-PRF-19500/358. The series covers a broad voltage range from 3.9 V to 200 V, offering versatile options for industrial and aerospace voltage regulation needs.

Replacement Considerations

Equivalent parts include the JAN1N3318B, JANTX1N3318B, and JANTXV1N3318B for qualified versions. Standard polarity equivalents are designated without the R suffix, such as 1N3318B. Cross-reference with the 1N4549B through 1N4556B series if alternative packaging or minor parameter variations are acceptable.