1N4957

Overview

The Microchip Technology 1N4957 is a military-qualified, voidless hermetically sealed 5-watt glass Zener diode. It provides a nominal Zener voltage of 9.1 V with a standard tolerance of ±5%. The device operates within a temperature range of -65°C to +175°C and features an axial lead 'E' package. Key electrical parameters include a maximum reverse leakage current of 25 µA at 6.9 V, a Zener impedance of 2.0 Ω at the test current of 150 mA, and a forward voltage of 1.5 V at 1.0 A. The component is designed for high-reliability applications requiring robust construction.

Feature Summary

• Hermetically sealed voidless-glass construction with internal metallurgical bonds
• Military qualification per MIL-PRF-19500/356 for high-reliability environments
• Inherently radiation hard and non-sensitive to electrostatic discharge
• Triple-layer passivation for enhanced structural robustness

Applications

• High-reliability aerospace systems where failure cannot be tolerated
• Military-grade voltage regulation circuits
• Radiation-hardened electronic subsystems
• Critical power supply protection in extreme temperature environments

Procurement Notes

Verify that the specific part number matches the required military specification level (e.g., JAN, JANTX) as suffixes denote different reliability grades. Confirm the package type corresponds to the axial lead configuration rather than surface mount variants. Ensure compliance with the manufacturer's environmental and trade compliance documentation prior to integration into sensitive defense or space hardware.

Selection Notes

Select this component when a 5-watt power rating and wide operating temperature range are required. The 9.1 V nominal voltage suits specific reference needs within the series. Consider the axial lead format for through-hole mounting. Evaluate thermal derating requirements based on ambient conditions, as power dissipation decreases linearly above 65°C lead temperature.

Part Context

This device belongs to the 1N4954 through 1N4996 series of 5-watt Zener voltage regulators manufactured by Microsemi (now Microchip). These industry-recognized components are designed for demanding applications. The series offers various voltage options from 3.3 V to 390 V, all sharing the same hermetically sealed glass package and military qualification standards.

Replacement Considerations

Surface-mount equivalents are available in the 1N4954US through 1N4996US series. Verify if the application requires the axial lead form factor or if the square end-cap MELF package is acceptable. Cross-reference other manufacturers' 5W Zener diodes only if they meet the same MIL-PRF-19500/356 qualification and physical dimensions.