Microchip Technology 1N4127

Overview

1N4127 from Microsemi is a 500 mW, 56 V, ±5% tolerance metallurgically bonded glass Zener diode in DO-35 package, qualified to JANS level per MIL-PRF-19500/435. It delivers stable voltage regulation with 300 Ω dynamic impedance at 250 mA test current, 40 µA max reverse leakage at 42.6 V, and +0.100 %/°C temperature coefficient - used in precision reference and power supply feedback circuits for aerospace avionics.

For engineers reviewing the 1N4127 datasheet, 1N4127 pinout, 1N4127 application, or 1N4127 equivalent, this page provides verified Zener voltage, thermal derating behavior, noise density (1 µV/√Hz), junction temperature range (–65 to +175 °C), and military qualification details critical for high-reliability analog design and radiation-hardened systems.

Technical Context

This Zener diode operates in reverse breakdown with cathode-banded polarity, requiring banded end to be positive relative to anode for regulation. Its metallurgical bond ensures low noise and stable long-term voltage drift under thermal cycling and radiation exposure.

Designed for operation at 250 mA Zener test current (IZT), it exhibits 300 Ω dynamic impedance (ZZT) and maintains ≤40 µA reverse leakage (IR) up to 42.6 V reverse voltage (VR), supporting stable regulation across –65 to +175 °C junction temperature range with linear power derating from 500 mW at 25 °C to zero at 175 °C.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) axial-leaded hermetically sealed glass package; cathode indicated by band; 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 1N4127, the 1N4127UR-1 offers identical regulation performance in a compact surface-mount form factor ideal for modern high-density layouts, while the 1N5255B provides basic 56 V regulation at lower cost but lacks military qualification, radiation tolerance, and low-noise capability required for high-integrity systems.

Availability

1N4127 is available at Aetrix Electronics and suitable for aerospace power regulation, avionics sensor biasing, and industrial control loop reference applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for 1N4127 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 Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and military-qualified analog and mixed-signal components.

The 1N4127 belongs to Microsemi's legacy 1N4099–1N4135 Zener series designed specifically for precision voltage regulation in mission-critical defense, space, and avionics systems where long-term stability and environmental resilience are mandatory.

FAQ

What is the Zener voltage tolerance for 1N4127?

The 1N4127 has a nominal Zener voltage of 56 V with a standard tolerance of ±5%, as defined in the JEDEC-registered specification and confirmed in the Electrical Characteristics table on page 3 of T4-LDS-0245-2 Rev. 1. This tolerance applies at 250 mA test current and 25 °C ambient temperature, and is maintained across the full qualified temperature range when operated within derated power limits. The 1N4127 does not offer tighter tolerances like 2% or 1% - those are available only in other members of the family such as 1N4127C or 1N4127D.

Is 1N4127 suitable for surface-mount assembly?

No, the standard 1N4127 is supplied in the axial-leaded DO-35 (DO-204AH) glass package and is intended for through-hole mounting. However, Microsemi offers the functionally identical 1N4127UR-1 in DO-213AA surface-mount packaging. The 1N4127UR-1 shares all electrical specifications including 56 V Zener voltage, 300 Ω dynamic impedance, and JANS qualification, but requires reflow soldering instead of wave or hand soldering. The 1N4127 itself is not compatible with SMT processes.

What is the maximum reverse leakage current for 1N4127?

The maximum reverse leakage current (IR) for 1N4127 is 40 µA, measured at a reverse voltage (VR) of 42.6 V and ambient temperature of 25 °C, as specified in the Electrical Characteristics table. This value reflects worst-case leakage under rated regulation conditions and remains valid across the full qualified junction temperature range when power dissipation is within derated limits. Lower leakage occurs at voltages below VR, and the device exhibits negligible forward conduction below 1.1 V.

Does 1N4127 require heatsinking in typical operation?

The 1N4127 does not require external heatsinking when operated at or below its rated 500 mW power dissipation at 25 °C lead temperature, provided standard PCB layout practices are followed: 1 oz copper, 4 mm² pads, and 1 mm wide × 25 mm long traces. Thermal resistance junction-to-ambient (RθJA) is 300 °C/W under these conditions. At elevated ambient temperatures or sustained high-current operation, linear derating begins at 50 °C lead temperature - reducing allowable power by 6.25 mW/°C until reaching zero at 175 °C.

How is polarity marked on the 1N4127 package?

The 1N4127 uses standard diode polarity marking: a visible cathode band is printed on the glass body near one lead end. During Zener regulation, the banded end (cathode) must be held at a more positive potential than the unbanded end (anode). Reversing polarity places the device in forward conduction mode, delivering ~1.1 V drop at 200 mA - not regulation. The band position is consistent across all DO-35 packaged devices in the 1N4099–1N4135 series and is verified in the Mechanical and Packaging section of T4-LDS-0245-2.