Microchip Technology 1N4731UR-1/TR

Overview

1N4731UR-1/TR from Microsemi is a surface-mount 1.0 W glass Zener diode in DO-213AB (MELF) package, rated for 4.3 V ±5% Zener voltage at 58 mA test current, with 9 Ω dynamic impedance and 10 μA maximum reverse leakage at 1 V. It operates from –65°C to +175°C and delivers stable voltage regulation in high-density power supply rails and precision reference circuits.

For engineers reviewing the 1N4731UR-1/TR datasheet, 1N4731UR-1/TR pinout, 1N4731UR-1/TR application, or 1N4731UR-1/TR equivalent, key selection criteria include its hermetic glass MELF construction, JEDEC-compliant surface-mount footprint, tight thermal resistance (130°C/W on FR4), and compatibility with automated reflow up to 260°C for 10 s.

Technical Context

This Zener diode functions as a two-terminal voltage reference device operating in reverse breakdown mode. Its electrical behavior is defined by a sharp knee at IZK = 1 mA (max 10 μA leakage at VR = 1 V), regulated Zener voltage of 4.3 V ±5%, and low dynamic impedance (9 Ω at IZT = 58 mA), enabling stable regulation across wide current and temperature ranges.

The DO-213AB glass MELF package provides hermetic sealing, radiation hardness per MicroNote 050, and low parasitic capacitance-critical for noise-sensitive analog references and high-reliability industrial control systems where axial-leaded alternatives are unsuitable.

Key Specifications

Pinout & Package

Package: DO-213AB glass MELF (hermetically sealed, leadless cylindrical surface-mount package with cathode band marking). Terminals are unmarked anode and banded cathode; polarity must be observed-cathode must be biased positive relative to anode for Zener regulation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener regulation applications.

Compared with 1N4731UR-1/TR, 1N4731AUR-TR offers identical regulation performance and reliability in the same DO-213AB package, while SMAJ4731A trades hermeticity and radiation tolerance for lower cost and wider distributor availability in plastic SMA format.

Availability

1N4731UR-1/TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, aerospace avionics, and medical diagnostic equipment requiring stable component supply across extended temperature and reliability requirements.

Supply support for 1N4731UR-1/TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, RF, and radiation-hardened components for defense, aerospace, and industrial markets.

The 1N4731UR-1/TR belongs to Microsemi's legacy surface-mount Zener diode family designed for high-density, high-stability voltage regulation in mission-critical systems where hermetic sealing and extreme temperature operation are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N4731UR-1/TR?

The 1N4731UR-1/TR has a Zener voltage tolerance of ±5%, confirmed by its "A"-grade designation in the Microsemi datasheet. This means its actual breakdown voltage falls between 4.085 V and 4.515 V at 58 mA test current and 30°C case temperature. The tolerance is guaranteed across the full operating temperature range of –65°C to +175°C, making it suitable for precision reference designs where stability matters.

Is the 1N4731UR-1/TR RoHS compliant?

Yes, the 1N4731UR-1/TR is RoHS compliant, indicated by the "e3" suffix in its full ordering designation per Microsemi documentation. It uses annealed matte-tin plating on terminals and meets all substance restrictions under Directive 2011/65/EU. This compliance applies to both the device itself and its tape-and-reel packaging (TR), ensuring suitability for modern environmentally regulated manufacturing lines.

What is the maximum steady-state power dissipation for the 1N4731UR-1/TR?

The 1N4731UR-1/TR is rated for 1.00 W steady-state power dissipation at case temperature (T_EC) below 125°C or ambient temperature (T_A) below 45°C when mounted on FR4 with recommended footprint. Derating is linear above these temperatures, reaching zero power at 175°C ambient. This rating is validated per Figure 1 in the Microsemi datasheet and assumes proper thermal pad layout per page 3.

Does the 1N4731UR-1/TR have radiation hardness certification?

Yes, the 1N4731UR-1/TR exhibits inherent radiation hardness per MicroNote 050, a documented Microsemi technical note validating its performance under total ionizing dose (TID) exposure. While not individually certified unless ordered with JAN/JANTX screening prefixes, its glass MELF construction and process provide baseline radiation tolerance suitable for low-earth orbit avionics and nuclear instrumentation where full MIL-PRF-19500 qualification is not mandated.

What does the "TR" suffix mean in 1N4731UR-1/TR?

"TR" stands for Tape and Reel packaging per EIA-481-B standard: 12 mm carrier tape, 1500 units per 7-inch reel. This format enables automated pick-and-place assembly in high-volume SMT production. The "-1" in "UR-1/TR" is a Microsemi internal revision or packaging variant identifier, not a functional change-it does not affect electrical or thermal specifications of the 1N4731UR-1/TR.