Microchip Technology 1N5281B

Overview

1N5281B from Microsemi is a 200 V, ±5% tolerance, 500 mW glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for operation from –65 °C to +175 °C, with 0.1 μA max reverse current at 160 V and +0.110 %/°C temperature coefficient - used for precision voltage reference and overvoltage protection in industrial power supplies.

For engineers reviewing the 1N5281B datasheet, 1N5281B pinout, 1N5281B application, or 1N5281B equivalent, key selection criteria include its 200 V nominal Zener voltage, 5% tolerance (B suffix), 0.1 μA leakage at VR = 160 V, DO-35 mechanical compatibility, and radiation-hardened construction per MicroNote 050.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage across a wide current range (IZK = 0.25 mA, IZT = 0.65 mA), with dynamic impedance ZZK = 7000 Ω at IZK and ZZT = 2500 Ω at IZT. Its thermal resistance is 250 °C/W junction-to-lead (3/8″ lead length) and 310 °C/W junction-to-ambient on FR4.

The device exhibits minimal capacitance (typ. <2 pF per Figure 2), is ESD-nonsensitive (MIL-STD-750 Method 1020), and features hermetically sealed glass construction with cathode band polarity marking - enabling reliable use in high-temp and radiation-prone environments.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) glass axial-leaded package: hermetically sealed, tin-lead or RoHS-compliant matte-tin plating, cathode indicated by colored band; weight 0.2 g; leads 3/8″ (10 mm) minimum from body for thermal rating compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5281B, the 1N5281C offers improved initial accuracy at identical power and thermal performance, while MMBZ5281B trades mechanical robustness and thermal capability for SMT compatibility - neither is pin-compatible due to differing packages and mounting methods.

Availability

1N5281B is available at Aetrix Electronics and suitable for industrial power supply reference, overvoltage protection clamp, aerospace sensor biasing, and downhole instrumentation reference requiring stable component supply across extended temperature and radiation environments.

Supply support for 1N5281B 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 and mixed-signal components for aerospace, defense, and industrial markets.

The 1N52xx series was designed specifically for ruggedized voltage regulation in mission-critical systems where long-term stability, radiation tolerance, and extreme temperature operation are mandatory.

FAQ

What is the nominal Zener voltage and tolerance of the 1N5281B?

The 1N5281B has a nominal Zener voltage of 200 V measured at test current IZT = 0.65 mA, with a guaranteed tolerance of ±5% (denoted by the "B" suffix). This tolerance is verified per JEDEC standards and applies across the full operating temperature range of –65 °C to +175 °C.

What is the maximum reverse leakage current specification for the 1N5281B?

The 1N5281B specifies a maximum reverse current (IR) of 0.1 μA when tested at VR = 160 V. This low leakage supports high-impedance bias networks and minimizes standby power loss in precision reference applications where signal integrity is critical.

Does the 1N5281B have radiation-hardened characteristics?

Yes, the 1N5281B is inherently radiation-hard per MicroNote 050, a documented characteristic of Microsemi's DO-35 Zener process. This makes the 1N5281B suitable for space-grade and nuclear instrumentation applications without requiring additional qualification testing.

What package type and marking does the 1N5281B use?

1N5281B uses the DO-35 (DO-204AH) glass axial-leaded package with cathode identified by a visible band. The part number "1N5281B" is laser-marked or etched directly onto the glass body, consistent with JEDEC registration and Microsemi's manufacturing standards.

Can the 1N5281B be used in surface-mount designs?

No - the 1N5281B is exclusively a through-hole DO-35 axial-leaded device. For surface-mount equivalents, Microsemi offers the MMBZ5281B in DO-213AA (MELF) package; however, it is not a drop-in replacement due to differing thermal, mechanical, and electrical ratings.