1N4491US/TR

Single Zener Diodes Overview

The Microchip Technology 1N4491US/TR is a surface mount Zener voltage regulator with a nominal breakdown voltage of 120 V and a maximum power dissipation of 1.5 W at 25 °C ambient temperature. It operates within a junction and storage temperature range of -65 °C to +175 °C. The device features a maximum dynamic impedance of 400 Ohms at the test current of 2.0 mA, a maximum reverse leakage current of 0.25 µA at 96.0 V, and a maximum continuous Zener current of 12 mA. It utilizes a voidless hermetically sealed glass package in an A (D-5A) MELF configuration.

Single Zener Diodes Feature Summary

• Hermetically sealed construction using void-less glass and internal metallurgical bonds for robust reliability.
• Military qualification available per MIL-PRF-19500/406 across JAN, JANTX, JANTXV, and JANS levels.
• Inherently radiation hard and non-sensitive to electrostatic discharge as defined by MIL-STD-750 method 1020.

Single Zener Diodes Applications

• High-reliability applications where component failure cannot be tolerated
• Voltage regulation over broad operating current and temperature ranges
• Radiation-hardened electronic systems

Single Zener Diodes Procurement Notes

Verify the specific reliability level suffix required for the application, as the base part number covers commercial through military grades. Confirm RoHS compliance status if environmental regulations apply, noting that compliant versions are restricted to commercial grade only. Ensure the tape and reel packaging meets EIA-481-B standards before finalizing procurement specifications.

Single Zener Diodes Selection Notes

Select this component when a 120 V Zener reference is needed in a surface mount form factor. The 1.5 W power rating supports steady-state operation at 25 °C, requiring thermal derating analysis for higher ambient temperatures. Verify that the 400 Ohm dynamic impedance meets the circuit's noise and stability requirements compared to lower impedance alternatives.

Single Zener Diodes Part Context

This device belongs to the 1N4460US through 1N4496US series of 1.5 Watt glass Zener diodes. These regulators provide industry-standard voltage selections ranging from 3.3 to 200 Volts with standard 5% tolerance. The series serves as the surface mount equivalent to popular JEDEC registered axial-lead series, maintaining similar electrical characteristics in a compact D-5A MELF package.

Single Zener Diodes Replacement Considerations

Direct replacements include other 1N4491 variants such as JAN1N4491CUS or JANTX1N4491CUS depending on the required reliability tier. Axial-lead equivalents like the 1N4491 may be used if board layout permits, though mechanical mounting differences must be addressed.