Microchip Technology 1N4730UR-1/TR

Overview

1N4730UR-1/TR from Microsemi is a surface-mount 1.0 W glass Zener diode with nominal Zener voltage 3.9 V ±5%, 64 mA test current, 9 Ω dynamic impedance at I_ZT, and maximum reverse current of 50 µA at 1 V. It operates from −65 °C to +175 °C and is used for precision voltage regulation in high-density power supply rails and reference circuits.

For engineers reviewing the 1N4730UR-1/TR datasheet, 1N4730UR-1/TR pinout, 1N4730UR-1/TR application, or 1N4730UR-1/TR equivalent, key selection criteria include Zener tolerance (±5%), DO-213AB MELF glass package thermal resistance (130 °C/W on FR4), surge current rating (1190 mA), and RoHS-compliant e3 marking capability.

Technical Context

This device implements a single-junction Zener breakdown mechanism in a hermetically sealed glass MELF case, delivering stable regulation across wide temperature and current ranges. Its 3.9 V nominal voltage targets low-voltage logic supply clamping and analog reference stabilization where tight tolerance and low dynamic impedance are required.

The DO-213AB package enables surface mounting with minimal parasitic capacitance and high thermal reliability. With 1.0 W steady-state dissipation at T_EC < 125 °C and forward voltage ≤1.2 V at 200 mA, it supports bidirectional protection and regulation functions without external biasing circuitry.

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 (length), B = 4.80–5.20 mm (diameter), C = 0.41–0.55 mm (band width). Cathode terminal is marked by a single dark band; device must be oriented with banded end positive for Zener operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4730A and SMAJ4730A, the 1N4730UR-1/TR uniquely combines DO-213AB glass MELF packaging, +175 °C operation, and hermetic reliability-making it the only option qualified for high-reliability, high-temperature SMT voltage regulation without layout or thermal redesign.

Availability

1N4730UR-1/TR is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor modules, and medical instrumentation requiring stable component supply, consistent Zener voltage tolerance, and high-temperature operational integrity.

Supply support for 1N4730UR-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) specializes in high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial markets.

The 1N47xxUR series was designed specifically for surface-mount voltage regulation in thermally demanding, high-density applications where hermetic sealing and extended temperature operation are mandatory.

FAQ

What is the Zener voltage tolerance for 1N4730UR-1/TR?

The 1N4730UR-1/TR has a nominal Zener voltage of 3.9 V with a tolerance of ±5%, indicated by the "A" suffix in its designation. This tolerance is verified at 64 mA test current and 30 °C junction temperature, and remains stable across its full −65 °C to +175 °C operating range. The 1N4730UR-1/TR does not support tighter tolerances like ±1% or ±2% unless explicitly ordered with "C" or "D" suffixes, which are not present in this variant.

Is 1N4730UR-1/TR RoHS compliant?

Yes, the "e3" suffix in the full part number 1N4730UR-1/TR/e3 confirms RoHS compliance per EU Directive 2011/65/EU. The device uses annealed matte-tin plating on terminals and meets all substance restrictions without compromising the hermetic glass MELF package integrity or thermal performance. Aetrix Electronics ships only e3-compliant units unless otherwise specified per customer request.

What is the maximum surge current rating for 1N4730UR-1/TR?

The 1N4730UR-1/TR has a maximum non-repetitive reverse surge current (I_S) of 1190 mA, measured using a ½ sine-wave pulse of 1/120 second duration at 25 °C ambient. This rating applies only to short-duration transients and must be derated linearly above 25 °C ambient per the device's thermal resistance profile. Continuous operation above 1.0 W requires end-cap heatsinking or PCB copper thermal relief.

How is polarity marked on 1N4730UR-1/TR?

The 1N4730UR-1/TR uses a single cathode band printed on the glass body to indicate polarity. The banded end is the cathode and must be connected to the higher-potential node (e.g., regulated voltage rail) for proper Zener regulation. The opposite, unmarked end is the anode and connects to ground or lower potential. This marking is visible under standard optical inspection and aligns with JEDEC DO-213AB mechanical standards.

What is the thermal resistance of 1N4730UR-1/TR when mounted on FR4?

When mounted on a standard FR4 PCB with 1 oz copper and the recommended footprint, the 1N4730UR-1/TR exhibits a junction-to-ambient thermal resistance of 130 °C/W. This value assumes optimal pad layout per Microsemi's published dimensions and is critical for calculating safe operating power at elevated ambient temperatures. End-cap–to–ambient resistance is 50 °C/W, supporting alternative heatsinking strategies.