1N4749UR

Overview

The Microchip Technology 1N4749UR is a high-reliability Zener diode designed for robust voltage regulation applications. It features a nominal Zener voltage of 24V with a tolerance of 10% and a power dissipation rating of 1W. The device utilizes silicon technology in a hermetically sealed glass MELF-2 (DO-213AB) package, ensuring isolation and environmental protection. It supports a maximum operating temperature of 175°C and exhibits a dynamic impedance of 25Ω at the specified test current.

Feature Summary

• Hermetically sealed glass construction for enhanced environmental durability
• High-reliability design suitable for demanding operational conditions
• Unidirectional single configuration for precise voltage clamping

Applications

• Military and aerospace electronic systems requiring radiation and thermal resilience
• High-reliability industrial control circuits
• Critical voltage reference stages in defense-grade instrumentation

Procurement Notes

Verify that the specific procurement order explicitly includes the UR suffix to ensure receipt of the hermetically sealed variant. Standard commercial equivalents lack the required sealing and reliability ratings. Confirm package designation matches DO-213AB specifications during incoming inspection to prevent integration errors in high-reliability assemblies.

Selection Notes

Select this component when hermetic sealing and extended thermal endurance are mandatory requirements. The 1W power rating and 175°C limit distinguish it from standard commercial Zener diodes. Ensure circuit designs account for the 25Ω dynamic impedance to maintain stability under varying load conditions within the specified voltage range.

Part Context

This part belongs to the Microchip 1N4749 series of Zener diodes, specifically engineered for high-reliability sectors. While sharing electrical characteristics with non-hermetic variants like the 1N4749AG, the UR designation signifies a specialized manufacturing process focused on long-term stability and resistance to harsh environmental factors typical in defense and space applications.

Replacement Considerations

Direct substitutes include other hermetically sealed 24V 1W Zener diodes in the DO-213AB package from qualified vendors. Verify that any replacement maintains the same hermetic seal certification and high-temperature rating to preserve system integrity.