Microchip Technology 1N5249B

Overview

1N5249B from Microsemi is a 500 mW, 19 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 6.6 Ω dynamic impedance at 23 mA test current, operates from –65°C to +175°C, and exhibits +0.086 %/°C temperature coefficient.

For engineers reviewing the 1N5249B datasheet, 1N5249B pinout, 1N5249B application, or 1N5249B equivalent, key selection criteria include its 19 V nominal Zener voltage, ±5% tolerance (B suffix), 500 mW power rating at 25°C, DO-35 mechanical compatibility, and stable regulation across industrial temperature extremes.

Technical Context

This discrete Zener diode functions as a two-terminal shunt voltage regulator, maintaining a stable reverse-biased breakdown voltage across its cathode–anode terminals when operated above its specified test current (IZT = 23 mA). Its regulation performance is defined by dynamic impedance (ZZT = 600 Ω max at IZK = 0.25 mA), leakage current (IR ≤ 0.1 μA at VR = 14.3 V), and thermal resistance (250 °C/W junction-to-lead).

The device uses hermetically sealed glass construction with tin-lead or RoHS-compliant matte-tin plating, enabling ESD insensitivity (MIL-STD-750 Method 1020) and inherent radiation hardness per MicroNote 050. Polarity is marked by a cathode band; operation requires the banded end to be positive relative to the anode for Zener conduction.

Key Specifications

Pinout & Package

Package: DO-35 (DO-204AH), hermetically sealed glass axial-leaded case with cathode band marking. Tin-lead or RoHS-compliant matte-tin plating, weight 0.2 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5249B, the BZX55C19 offers identical Zener voltage, tolerance, package, and impedance specifications, enabling seamless substitution without layout or schematic changes; the 1N4742A serves a different voltage class and requires mechanical redesign due to DO-41 size and 1 W rating.

Availability

1N5249B is available at Aetrix Electronics and suitable for industrial power monitoring, automotive sensor reference, and military signal conditioning requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 1N5249B 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, radiation-hardened, and high-temperature analog and mixed-signal components.

The 1N52xxB series was developed to deliver JEDEC-standardized, high-stability Zener references for aerospace, defense, and industrial systems demanding guaranteed parametric limits and extended environmental operation.

FAQ

What is the nominal Zener voltage and tolerance of the 1N5249B?

The 1N5249B has a nominal Zener voltage of 19 V with a tolerance of ±5%, as indicated by the "B" suffix per JEDEC specification. This tolerance is guaranteed across the full operating temperature range and is verified at 23 mA test current (IZT), making it suitable for precision reference designs where voltage predictability is critical.

What package type and mounting configuration does the 1N5249B use?

The 1N5249B uses the DO-35 (DO-204AH) hermetically sealed glass axial-leaded package. It features flexible axial leads with cathode polarity marked by a visible band; the banded end must be connected to the higher-potential node for proper Zener regulation, and leads are solderable per MIL-STD-750 Method 2026.

What is the maximum power dissipation and thermal derating behavior of the 1N5249B?

The 1N5249B is rated for 500 mW at 25°C ambient or lead temperature (TL), with linear derating to zero at 175°C. Thermal resistance is 250 °C/W junction-to-lead at 3/8″ lead length, meaning each 125°C rise above 25°C reduces usable power by 500 mW - critical for high-temperature PCB placement near heat sources.

How does the 1N5249B perform under radiation exposure and ESD stress?

The 1N5249B is inherently radiation-hardened per MicroNote 050 and ESD-insensitive per MIL-STD-750 Method 1020. These characteristics are intrinsic to its glass-encapsulated DO-35 construction and do not require external hardening - enabling use in space, nuclear, and high-reliability industrial systems without added protection circuitry.

Is the 1N5249B RoHS compliant, and how is compliance indicated?

Yes, RoHS-compliant versions of the 1N5249B are available with the "e3" suffix (e.g., 1N5249Be3), indicating annealed matte-tin plating per JEDEC standards. Standard 1N5249B uses tin-lead plating; the e3 variant replaces lead with RoHS-compliant materials while maintaining identical electrical and mechanical performance and solderability.