Microchip Technology 1N5229A

Overview

1N5229A from Microsemi is a 4.3 V, ±10% tolerance, 500 mW glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 20 mA test current, 22 Ω dynamic impedance at IZT, and -65°C to +175°C operating temperature - used for precision voltage reference and low-power regulation in analog sensor interfaces and power supply feedback loops.

For engineers reviewing the 1N5229A datasheet, 1N5229A pinout, 1N5229A application, or 1N5229A equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (250°C/W junction-to-lead), reverse leakage (50 μA @ 3.4 V), temperature coefficient (+/-0.055 %/°C), and RoHS-compliant e3 suffix availability.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage across its terminals under varying load and temperature conditions. Its DO-35 glass package provides hermetic sealing and inherent radiation hardness per MicroNote 050, with cathode indicated by band and polarity requiring banded end positive for regulation.

Electrical behavior is defined at 25°C with 20 mA test current (IZT); dynamic impedance (ZZT = 22 Ω) is measured at IZK = 0.25 mA, and temperature coefficient applies over -65°C to +175°C ambient range with specified derating above 50°C lead temperature.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) hermetically sealed glass axial-leaded package with cathode identified by colored band; leads are tin-lead or RoHS-compliant matte-tin plated, solderable per MIL-STD-750 Method 2026.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5229A, 1N4733A shifts regulation to 5.1 V with improved tolerance but different thermal coefficient (+0.030%/°C), while BZX55-C4V3 matches voltage exactly with tighter tolerance and lower leakage but slightly higher impedance - choice depends on whether voltage match, leakage budget, or tolerance priority dominates the design.

Availability

1N5229A is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, and power supply feedback applications requiring stable component supply across industrial control, aerospace subsystems, and test equipment manufacturing.

Supply support for 1N5229A 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, mixed-signal, and radiation-hardened components for defense, aerospace, and industrial markets.

The 1N52xx series was designed for general-purpose, high-stability Zener regulation in mission-critical analog circuits where wide temperature range, hermetic packaging, and JEDEC standardization are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N5229A?

The 1N5229A has a nominal Zener voltage of 4.3 V with a ±10% tolerance, meaning its actual breakdown voltage falls between 3.87 V and 4.73 V at 20 mA test current and 25°C. This tolerance is designated by the "A" suffix per Microsemi's part numbering convention and is verified per JEDEC 1N5221–1N5281B specifications.

Does the 1N5229A require a heatsink in typical PCB mounting?

No, the 1N5229A does not require an external heatsink under typical conditions. With a thermal resistance of 310°C/W junction-to-ambient on FR4 board (1 oz Cu, 4 mm² pads), it dissipates 0.5 W safely up to 50°C ambient. Derating begins above that temperature per Figure 1 in the datasheet, and lead-length thermal path (250°C/W) supports higher local dissipation if leads are extended.

Can the 1N5229A be used in surface-mount designs?

The 1N5229A itself is axial-leaded DO-35 and not surface-mount compatible, but Microsemi offers direct surface-mount equivalents: MLL5229A in DO-213AA (MELF) package. These share identical electrical specs including 4.3 V Zener voltage and ±10% tolerance, and are marked with the same "A" suffix for consistency in BOM management.

What is the maximum reverse leakage current for the 1N5229A?

The maximum reverse leakage current for the 1N5229A is 50 μA at VR = 3.4 V (80% of nominal Zener voltage), measured at 25°C. This value is specified in the Electrical Characteristics table and reflects worst-case off-state conduction prior to regulation onset - critical for low-power bias networks and high-impedance sensing nodes.

Is the 1N5229A RoHS compliant?

Yes, the 1N5229A is available in RoHS-compliant form with the "e3" suffix (e.g., 1N5229Ae3), indicating annealed matte-tin plating per J-STD-609. Standard versions use tin-lead plating; the e3 variant substitutes lead-free finish while maintaining identical electrical performance, thermal ratings, and mechanical dimensions per Microsemi's DO-35 specification.