Microchip Technology 1N5239A

Overview

1N5239A from Microsemi is a 500 mW, 9.1 V ±10% glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for -65°C to +175°C operation, with 10 Ω zener impedance at 20 mA test current and 6.7 V maximum zener voltage temperature coefficient. It serves as a precision voltage reference in low-power analog circuits, power supply feedback loops, and overvoltage protection clamps.

For engineers reviewing the 1N5239A datasheet, 1N5239A pinout, 1N5239A application, or 1N5239A equivalent, this page delivers verified electrical parameters, thermal derating behavior, package dimensions, JEDEC-compliant screening options, and direct alternatives with documented tolerance and impedance differences.

Technical Context

The 1N5239A operates as a two-terminal reverse-biased voltage regulator with a nominal breakdown voltage of 9.1 V at 20 mA (IZT), exhibiting a sharp knee in its I-V curve validated by dual-point dynamic impedance measurement per MicroNote 202. Its zener impedance (ZZT = 10 Ω) is measured using 10% RMS AC superimposed on DC IZT, ensuring stable regulation under varying load conditions.

Thermal performance is defined by junction-to-lead resistance of 250 °C/W at 3/8″ lead length and junction-to-ambient resistance of 310 °C/W on FR4 with specified copper pad geometry. The device features hermetically sealed glass construction, cathode band polarity marking, and RoHS-compliant matte-tin plating per MIL-STD-750 Method 2026.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) hermetically sealed glass axial-leaded package with cathode indicated 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 regulation applications.

Compared with 1N5239A, the 1N4739A offers higher power headroom but requires board real estate and thermal management for 1 W dissipation, while the MMBZ5239BS enables miniaturization and tighter voltage control at the cost of reduced ruggedness and manual repairability.

Availability

1N5239A is available at Aetrix Electronics and suitable for low-power voltage reference, overvoltage clamp protection, and power supply feedback divider applications requiring stable component supply across industrial, aerospace, and automotive programs.

Supply support for 1N5239A 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 1N52xx series was designed specifically for precision voltage regulation in mission-critical systems where wide temperature operation, hermetic sealing, and JEDEC-standardized parametric consistency are mandatory.

FAQ

What is the maximum power dissipation of the 1N5239A at 25°C?

The 1N5239A has a maximum power dissipation of 0.5 W at 25°C ambient temperature with 3/8″ lead length from the body. Derating begins linearly beyond 25°C, reaching zero dissipation at 175°C case temperature per Figure 1. This rating assumes proper lead heat sinking and is critical for thermal design validation in sealed enclosures or high-temperature environments where the 1N5239A is deployed.

Does the 1N5239A have a guaranteed zener impedance specification?

Yes, the 1N5239A specifies a maximum zener impedance (ZZT) of 10 Ω at 20 mA test current (IZT), measured using 10% RMS AC superimposed on DC IZT per MicroNote 202. This value is guaranteed for all units and directly impacts regulation accuracy under dynamic load conditions - a key differentiator from non-specified or typical-only Zener diodes where impedance may vary widely unit-to-unit.

What does the "A" suffix indicate in 1N5239A?

The "A" suffix in 1N5239A denotes a ±10% tolerance on the nominal 9.1 V zener voltage at 25°C, as defined in the JEDEC 1N52xx family specification. This distinguishes it from "B" (±5%), "C" (±2%), and "D" (±1%) variants. The "A" version is optimized for cost-sensitive applications where moderate voltage accuracy suffices, such as general-purpose clamping or coarse reference generation.

Is the 1N5239A suitable for high-reliability aerospace applications?

Yes, the 1N5239A supports aerospace use through optional military screening levels: adding MQ, MX, MV, or MSP prefixes enables compliance with MIL-PRF-19500 for JAN, JANTX, JANTXV, and JANS grades respectively - all requiring the "-1" internal bond suffix. These versions undergo rigorous environmental testing, lot traceability, and radiation hardness verification per MicroNote 050, making them qualified for flight-critical subsystems.

How is polarity marked on the 1N5239A package?

The 1N5239A uses a cathode band - a single colored ring near one end of the DO-35 glass body - to identify the cathode terminal. For correct Zener operation, the banded end must be held at a higher potential than the anode (i.e., reverse biased). This marking is laser-etched or painted per MIL-STD-750 and remains visible after soldering, supporting visual inspection and automated optical alignment in assembly.