Microchip Technology 1N4743UR/TR

Overview

1N4743UR/TR from Microsemi is a surface-mount 1.0 W glass Zener diode with a nominal Zener voltage of 13 V, ±5% tolerance (A-suffix), 10 Ω dynamic impedance at 19 mA test current, and maximum reverse current of 5 µA at 9.9 V. It operates from –65°C to +175°C and is hermetically sealed in a DO-213AB MELF package for high-reliability voltage regulation in space-constrained power supply rails.

For engineers reviewing the 1N4743UR/TR datasheet, 1N4743UR/TR pinout, 1N4743UR/TR application, or 1N4743UR/TR equivalent, key selection criteria include its 13 V regulation accuracy, 1.0 W steady-state power rating at T_EC < 125°C, low 10 Ω Z_ZT, and compatibility with automated SMT assembly per EIA-481-B tape-and-reel packaging.

Technical Context

This device functions as a precision shunt voltage regulator, maintaining stable output voltage across wide operating current (19 mA I_ZT, 344 mA I_ZM at 50°C) and temperature ranges. Its glass MELF construction provides hermetic sealing, inherent radiation hardness per MicroNote 050, and low parasitic capacitance-critical for noise-sensitive analog and aerospace power conditioning.

The 1N4743UR/TR uses a single-junction Zener mechanism with sharp breakdown knee (verified via dual-point Z_ZK measurement at 0.1×I_ZT), specified dynamic impedance of 10 Ω at 19 mA, and forward voltage ≤1.2 V at 200 mA-enabling bidirectional protection and clamping roles beyond basic regulation.

Key Specifications

Pinout & Package

Hermetically sealed DO-213AB glass MELF package: cylindrical body with axial terminals; cathode indicated by single black band. No discrete pins-device mounts end-to-end on PCB pads per recommended footprint (A = 2.39–2.66 mm, B = 4.80–5.20 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4743AUR and SMAJ4743A, the 1N4743UR/TR uniquely balances SMT manufacturability, hermetic reliability, and tight regulation-making it optimal for volume production of high-integrity power rails where long-term parametric stability matters.

Availability

1N4743UR/TR is available at Aetrix Electronics and suitable for industrial power supplies, aerospace avionics, and automotive engine control units requiring stable component supply with full traceability and long-lifecycle support.

Supply support for 1N4743UR/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) designs high-reliability semiconductors for aerospace, defense, and industrial markets, emphasizing radiation tolerance, hermetic packaging, and extended temperature performance.

The 1N4743UR/TR belongs to Microsemi's surface-mount Zener diode family engineered for high-density voltage regulation in mission-critical systems where parameter stability and environmental resilience are non-negotiable.

FAQ

What is the Zener voltage tolerance for 1N4743UR/TR?

The 1N4743UR/TR has a nominal Zener voltage of 13 V with ±5% tolerance, confirmed by the "A" suffix in its designation per Microsemi's datasheet revision D. This tolerance applies at 30°C with 19 mA test current and is guaranteed across the full operating temperature range of –65°C to +175°C. The 1N4743UR/TR does not support tighter tolerances like ±1% or ±2%-those require "D" or "C" suffix variants.

Is 1N4743UR/TR RoHS compliant?

Yes, the 1N4743UR/TR is RoHS compliant, indicated by the "e3" suffix in its full part number per Microsemi documentation. It features annealed matte-tin plating on terminals, meeting MIL-STD-750 Method 2026 solderability requirements and EU Directive 2011/65/EU. Lead-free assembly is supported with peak reflow temperatures up to 260°C for 10 seconds.

What is the maximum power dissipation of 1N4743UR/TR at 70°C ambient?

At 70°C ambient temperature on an FR4 board with 1 oz copper and Microsemi's recommended pad layout, the 1N4743UR/TR derates to approximately 0.75 W. This follows the linear derating curve in Figure 1 of the datasheet: 1.0 W at ≤45°C ambient, decreasing by 12.5 mW/°C above that point. At 70°C, the reduction is (70 − 45) × 0.0125 = 0.3125 W, yielding 0.6875 W-rounded to 0.75 W for design margin.

Does 1N4743UR/TR have a specified junction-to-case thermal resistance?

Yes, the 1N4743UR/TR has a junction-to-end-cap thermal resistance (R_θJC) of 50°C/W, measured from die to metalized end cap surface. This value enables accurate thermal modeling when the end cap is thermally coupled to a heatsink or large copper pour. It differs from junction-to-ambient (130°C/W on FR4), which assumes no external heat sinking.

Can 1N4743UR/TR be used for bidirectional ESD protection?

No-1N4743UR/TR is a unidirectional Zener diode optimized for reverse-bias regulation. While it conducts forward current ≤1.2 V at 200 mA, it lacks symmetric clamping characteristics or specified ESD ratings (e.g., IEC 61000-4-2). For bidirectional protection, dedicated TVS diodes like SMAJ13A or P6SMB13A are appropriate; the 1N4743UR/TR should only be used in shunt regulation or unidirectional clamping roles.