Diodes Incorporated 1N5239B-T

Overview

1N5239B-T from Diodes Incorporated is a 500mW, 9.1V ±5% tolerance surface-mount Zener diode in a hermetic DO-35 glass package, with 10Ω maximum zener impedance at 20mA test current, 3.0µA maximum reverse leakage at 7.0V, and +0.068%/°C temperature coefficient-used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N5239B-T datasheet, 1N5239B-T pinout, 1N5239B-T application, or 1N5239B-T equivalent, this part serves as a stable, RoHS-compliant 9.1V Zener reference in space-constrained designs where thermal stability, low leakage, and tight voltage tolerance are critical-especially in sensor signal conditioning, power supply feedback, and portable battery monitoring systems.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain a stable 9.1V reference across load and line variations. Its DO-35 glass package provides hermetic sealing and high reliability under thermal cycling, while the ±5% V_Z tolerance and +0.068%/°C TC ensure predictable regulation in ambient temperatures from –65°C to +175°C.

With 500mW power dissipation and 300°C/W junction-to-ambient thermal resistance (at TL ≤75°C), it supports continuous operation up to 55mA at 9.1V when properly heatsinked. The 10Ω dynamic impedance at I_ZT = 20mA enables low-noise voltage clamping in feedback loops and reference buffers.

Key Specifications

Pinout & Package

DO-35 glass axial package with cathode band marking; two-terminal device with no internal circuitry-cathode (banded end) and anode (unmarked end). Leads are solderable per MIL-STD-202, Method 208.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5239B and 1N4739A, the 1N5239B-T offers optimal balance of hermetic reliability, 500mW capability, and low leakage in a compact DO-35 form-making it preferred for high-stability, medium-power Zener references where long-term parameter drift must be minimized.

Availability

1N5239B-T is available at Aetrix Electronics and suitable for automotive engine control units, industrial sensor signal conditioning, and portable medical device battery monitoring requiring stable component supply and long-lifecycle support.

Supply support for 1N5239B-T 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

The 1N52xxB series belongs to Diodes' legacy Zener diode product line, engineered specifically for high-reliability voltage reference and regulation in industrial, automotive, and medical applications demanding hermetic packaging and tight parametric control.

FAQ

Is the 1N5239B-T still in active production?

No-the 1N5239B-T is officially obsolete per Diodes Incorporated's DS18006 Rev. 19 (September 2019). It has been superseded by the MMSZ5239B for new designs. However, Aetrix Electronics maintains limited legacy stock with full traceability and supports obsolescence mitigation for existing production programs.

What is the maximum steady-state current for reliable operation?

At 25°C ambient and with leads held at ≤75°C (9.5mm length), the 1N5239B-T supports up to 55mA continuous current (500mW ÷ 9.1V). Derating is required above 75°C lead temperature per R_θJA = 300°C/W, reducing usable current linearly to zero at ~175°C junction temperature.

Can this diode be used in series or parallel configurations?

Series connection is acceptable for higher reference voltages, provided current matching and thermal coupling are managed. Parallel use is not recommended due to mismatched Zener impedances and thermal runaway risk-each diode must be individually biased to avoid current hogging and localized overheating.

Does the DO-35 package support automated optical inspection (AOI)?

Yes-the DO-35's cylindrical glass body and distinct cathode band enable reliable AOI detection during SMT placement verification. Its uniform reflectivity and sharp band contrast meet IPC-A-610 Class 2 criteria for automated visual defect identification in high-volume assembly lines.