Microchip Technology 1N4734UR/TR

Overview

1N4734UR/TR from Microsemi is a surface-mount 1.0 W glass-encapsulated Zener diode with a nominal Zener voltage of 5.6 V, ±5% tolerance (A-suffix), 45 mA test current, 5 Ω dynamic impedance at I_ZT, and 10 μA maximum reverse leakage at 4.2 V. It operates from −65 °C to +175 °C and is used for precision voltage regulation in high-density power supply feedback loops.

For engineers reviewing the 1N4734UR/TR datasheet, 1N4734UR/TR pinout, 1N4734UR/TR application, or 1N4734UR/TR equivalent, key selection criteria include Zener voltage stability over temperature, low dynamic impedance for tight regulation, hermetic DO-213AB MELF package suitability for high-reliability environments, and RoHS-compliant e3 marking availability.

Technical Context

This device functions as a two-terminal voltage reference diode operating in reverse breakdown. Its Zener voltage is specified at 5.6 V with 45 mA test current and exhibits 5 Ω dynamic impedance (Z_ZT) at that bias point, ensuring stable regulation under varying load conditions.

The DO-213AB glass MELF package provides hermetic sealing, radiation hardness per MicroNote 050, and thermal resistance of 130 °C/W junction-to-ambient on FR4 with recommended footprint-critical for sustained 1.0 W dissipation in compact layouts.

Key Specifications

Pinout & Package

Package: DO-213AB glass MELF - hermetically sealed, leadless cylindrical surface-mount package with cathode band marking; dimensions: A = 2.39–2.66 mm (diameter), B = 4.80–5.20 mm (length), C = 0.41–0.55 mm (band width).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4734A and SMAJ4734A, the 1N4734UR/TR uniquely combines surface-mount compatibility, hermetic glass packaging, radiation hardness, and −65 °C to +175 °C operation-making it the sole choice for high-reliability, high-temperature, and space-constrained applications requiring long-term parametric stability.

Availability

1N4734UR/TR is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, and automotive engine control units requiring stable component supply with full traceability and lifecycle support.

Supply support for 1N4734UR/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 and mixed-signal components for aerospace, defense, and industrial markets.

The 1N4734UR/TR belongs to Microsemi's surface-mount Zener diode family designed specifically for high-density, high-temperature, and mission-critical voltage regulation where hermeticity and radiation tolerance are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N4734UR/TR?

The 1N4734UR/TR has a nominal Zener voltage of 5.6 V with a tolerance of ±5%, indicated by the "A" suffix in its designation. This tolerance is measured at 45 mA test current and 30 °C case temperature, and remains stable across its full operating temperature range of −65 °C to +175 °C. The 1N4734UR/TR does not support tighter tolerances like ±1% or ±2%-those require suffixes "D" or "C", respectively, which are not present in this part number.

Does the 1N4734UR/TR have RoHS compliance certification?

Yes, the 1N4734UR/TR carries the "e3" suffix, indicating full RoHS compliance per EU Directive 2011/65/EU. Its terminals feature annealed matte-tin plating solderable per MIL-STD-750 Method 2026, and the device meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1). The "e3" marking is laser-etched on the cathode band of the DO-213AB glass MELF body.

What is the maximum steady-state power dissipation for the 1N4734UR/TR on a standard PCB?

The 1N4734UR/TR delivers 1.00 W steady-state power dissipation when mounted on an FR4 printed circuit board with 1 oz copper and the manufacturer-recommended pad layout. At ambient temperatures above 45 °C, power must be linearly derated per Figure 1 in the datasheet, reaching zero at 125 °C ambient. Derating is based on 130 °C/W junction-to-ambient thermal resistance-not junction-to-case-so heatsinking the end cap is ineffective without direct thermal vias.

How is polarity identified on the 1N4734UR/TR?

Polarity on the 1N4734UR/TR is marked by a single black cathode band located near one end of the DO-213AB glass MELF body. During Zener regulation, the banded (cathode) end must be held at a higher potential than the unbanded (anode) end. This polarity is critical: reverse biasing the device incorrectly will result in forward conduction (~1.2 V drop at 200 mA), not regulation. No alphanumeric marking is present-only the band identifies cathode orientation.

Can the 1N4734UR/TR replace the through-hole 1N4734A in existing designs?

No, the 1N4734UR/TR cannot serve as a drop-in replacement for the 1N4734A due to fundamental package incompatibility: the 1N4734UR/TR uses DO-213AB glass MELF (surface-mount), while the 1N4734A uses DO-41 (axial-leaded). Layout redesign, reflow profile adjustment, and thermal validation are required. Though electrically equivalent, the 1N4734UR/TR offers superior thermal resistance to ambient (130 °C/W vs. 75 °C/W for 1N4734A's junction-to-lead), making it better suited for high-density SMT assemblies.