Diodes Incorporated 1N5231B-T

Overview

1N5231B-T from Diodes Incorporated is a 5.1 V, ±5% tolerance, 500 mW surface-mount Zener diode in a hermetic DO-35 glass package, optimized for voltage regulation and reference applications in low-power analog circuits, power supply feedback loops, and overvoltage protection. It delivers stable Zener impedance of 17 Ω at 20 mA test current, operates from –65°C to +175°C, and features Sn96.5Ag3.5 lead finish compliant with RoHS 3.

For engineers reviewing the 1N5231B-T datasheet, 1N5231B-T pinout, 1N5231B-T application, or 1N5231B-T equivalent, key selection criteria include its tight 5.1 V nominal Zener voltage, low 17 Ω dynamic impedance at I_ZT, temperature coefficient of +0.030 %/°C, and suitability for space-constrained PCBs requiring high thermal stability and hermetic reliability.

Technical Context

This Zener diode functions as a precision voltage reference by operating in reverse breakdown, where it maintains a stable 5.1 V across its terminals within ±5% tolerance under 20 mA DC test current. Its low 17 Ω Zener impedance ensures minimal output voltage variation under load changes, while the +0.030 %/°C temperature coefficient enables predictable drift compensation in ambient-varying environments.

The DO-35 glass package provides hermetic sealing and thermal resistance of 300 °C/W (junction-to-ambient), supporting reliable operation up to +175°C junction temperature. The cathode band polarity marking and Sn96.5Ag3.5 solderable terminations comply with MIL-STD-202 and J-STD-020 Level 1 moisture sensitivity requirements.

Key Specifications

Pinout & Package

Package: Hermetic DO-35 glass case with axial leads, cathode band marking, and Sn96.5Ag3.5 solderable terminations. Dimensions: A ≤25.4 mm, B ≤4.00 mm, C ≤0.60 mm, D ≤2.00 mm (all in mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5231B and 1N4733A, the 1N5231B-T offers a unique balance of hermetic reliability, moderate power handling, and legacy DO-35 compatibility-making it preferred for repair, military-grade replacements, and applications where moisture resistance and wide temperature operation are prioritized over SMT automation or ultra-low impedance.

Availability

1N5231B-T is available at Aetrix Electronics and suitable for voltage reference design, power supply feedback, and overvoltage protection requiring stable component supply in industrial control, test equipment, and legacy system maintenance.

Supply support for 1N5231B-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 semiconductor manufacturer specializing in discrete, analog, and mixed-signal devices, with emphasis on high-reliability, energy-efficient solutions for industrial, computing, and consumer markets.

The 1N52xxB series belongs to Diodes' legacy Zener diode product line, engineered for precision voltage regulation in cost-sensitive, thermally demanding, and long-lifecycle applications where hermetic packaging and wide temperature operation are essential.

FAQ

What is the maximum continuous power dissipation for 1N5231B-T at 75°C ambient?

The 1N5231B-T is rated for 500 mW power dissipation provided leads are maintained at ≤75°C with 9.5 mm lead length. Above 75°C ambient, derating applies at 1.67 mW/°C based on R_θJA = 300 °C/W. At 75°C ambient, full 500 mW remains valid; at 100°C ambient, maximum allowable power drops to 458 mW.

Is 1N5231B-T suitable for use in RoHS-compliant production?

Yes - the 1N5231B-T features a lead-free Sn96.5Ag3.5 finish and complies fully with EU RoHS Directives 2002/95/EC, 2011/65/EU, and 2015/863/EU (RoHS 3). All applicable exemptions have been applied, and halogen/antimony content meets Diodes Incorporated's "Green" definition per their quality documentation.

How does the +0.030 %/°C temperature coefficient affect regulation accuracy over temperature?

At 25°C, the +0.030 %/°C coefficient translates to +1.53 mV/°C drift around the 5.1 V nominal. Over a –40°C to +85°C operating range, total drift is approximately ±191 mV (±3.7%), which must be accounted for in reference-critical designs. For tighter stability, circuit-level compensation or TC-matched resistor networks are recommended.

Why is the 1N5231B-T marked as obsolete, and what is the recommended replacement?

Diodes Incorporated has discontinued the 1N5231B-T as part of the broader 1N5221B–1N5267B family obsolescence. The official replacement is MMSZ5231B - an SOD-123 surface-mount variant with identical electrical specs but reduced power rating (350 mW) and different package. Legacy DO-35 form factor and hermetic reliability make the 1N5231B-T still viable for repair and niche applications where MMSZ5231B's limitations are unacceptable.