Microchip Technology 1N5254B

Overview

1N5254B from Microsemi is a 500 mW, 27 V ±5% glass axial-lead Zener diode in DO-35 (DO-204AH) package, designed for precision voltage regulation in low-power analog circuits, reference supplies, and overvoltage protection. It delivers 27 V nominal Zener voltage at 41 mA test current, with 600 Ω maximum Zener impedance at knee current and ±0.090 %/°C temperature coefficient.

For engineers reviewing the 1N5254B datasheet, 1N5254B pinout, 1N5254B application, or 1N5254B equivalent, key selection factors include its tight ±5% tolerance (B suffix), low 0.1 μA max reverse leakage at 21.6 V, stable thermal performance up to +175°C, and compatibility with manual or wave soldering per MIL-STD-750.

Technical Context

The 1N5254B operates as a two-terminal shunt regulator, maintaining stable output voltage by conducting reverse current above its breakdown threshold. Its Zener mechanism provides predictable regulation across 0.25–41 mA operating range, with minimal capacitance (<2 pF typical) and inherent radiation hardness per MicroNote 050.

It features a sharp breakdown knee verified via dual-point Zener impedance measurement (at IZT and IZK), ensuring unit stability. The device is polarity-marked with a cathode band and requires cathode-positive biasing relative to anode for regulation - a critical design constraint for correct circuit integration.

Key Specifications

Pinout & Package

Hermetically sealed DO-35 (DO-204AH) glass axial-leaded package with tin-lead or RoHS-compliant matte-tin plating. Cathode identified by single black band; anode is unmarked end. Mounting requires ≥10 mm lead length from body for rated thermal resistance (250°C/W junction-to-lead).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5254B, 1N4748A offers higher power margin but requires board real estate and thermal management for 1 W operation, while MMBZ5254B matches electrical performance in SMT format but eliminates axial-lead serviceability and manual rework capability.

Availability

1N5254B is available at Aetrix Electronics and suitable for precision voltage reference, overvoltage protection, and temperature-stable bias network applications requiring stable component supply, long-term obsolescence resilience, and traceable sourcing.

Supply support for 1N5254B 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 aerospace, defense, and industrial markets.

The 1N52xxB series was engineered for mission-critical voltage regulation where long-term stability, wide temperature operation, and JEDEC-standard interchangeability are mandatory - particularly in avionics, downhole tools, and military-grade power supplies.

FAQ

What is the nominal Zener voltage and tolerance of the 1N5254B?

The 1N5254B has a nominal Zener voltage of 27 V with a guaranteed tolerance of ±5%, as indicated by the "B" suffix per JEDEC specification. This tolerance is validated at 25°C with 41 mA test current and remains stable across its full operating temperature range of −65°C to +175°C, making it suitable for high-reliability reference applications where voltage accuracy must be maintained under thermal stress.

What package type and marking does the 1N5254B use?

The 1N5254B uses a hermetically sealed DO-35 (DO-204AH) glass axial-leaded package with tin-lead or RoHS-compliant matte-tin plating. It is marked with the full part number "1N5254B" on the glass body, and the cathode is identified by a single black band - the banded end must be biased positive relative to the anode for proper Zener regulation.

What is the maximum reverse leakage current for the 1N5254B and at what voltage is it specified?

The 1N5254B specifies a maximum reverse leakage current of 0.1 μA at a reverse voltage (VR) of 21.6 V - which is 80% of its nominal 27 V Zener voltage. This ultra-low leakage ensures minimal error current in high-impedance bias networks and contributes to stable operation in precision analog circuits such as voltage references and sensor conditioning stages.

How does the temperature coefficient of the 1N5254B affect its performance in varying thermal environments?

The 1N5254B has a positive temperature coefficient of +0.090 %/°C, meaning its Zener voltage increases by approximately 24.3 mV per 1°C rise in junction temperature. This predictable drift enables accurate thermal compensation in reference designs and confirms suitability for applications operating from −65°C to +175°C, including downhole instrumentation and aerospace power systems.

Can the 1N5254B be used in surface-mount designs?

No - the 1N5254B is exclusively offered in the through-hole DO-35 axial-leaded package. For surface-mount equivalents with identical 27 V ±5% regulation, Microsemi offers the MMBZ5254B in SOD-80 (MELF) package. That part shares the same electrical specifications but requires reflow soldering and lacks the axial-lead serviceability and manual prototyping flexibility of the 1N5254B.