Microchip Technology 1N4112

Overview

1N4112 from Microsemi is a 500 mW, 18.0 V ±5% metallurgically bonded glass Zener diode in DO-35 (DO-204AH) package, qualified to JANTXV level per MIL-PRF-19500/435 for high-reliability voltage regulation in aerospace and defense power supplies.

For engineers reviewing the 1N4112 datasheet, 1N4112 pinout, 1N4112 application, or 1N4112 equivalent, this part delivers stable 18 V reference under wide current/temperature ranges, low noise density (1 µV/√Hz), and radiation-hardened operation - critical for precision analog biasing and regulated DC-DC feedback loops.

Technical Context

This Zener diode operates in reverse breakdown with cathode band indicating polarity, requiring banded end to be positive relative to anode for regulation. Its metallurgical bond ensures mechanical stability and long-term parameter consistency across thermal cycling.

It exhibits a +0.090 %/°C temperature coefficient, dynamic impedance of 100 Ω at 250 mA test current, and maximum reverse leakage of 0.05 µA at 13.7 V - enabling accurate voltage clamping in low-power reference circuits without active compensation.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) axial-leaded glass package with hermetically sealed construction; cathode indicated by single black band on glass body; anode is unbanded end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4112, 1N4746A offers higher power but lacks radiation hardness and military screening; SMF18A serves transient clamping, not stable DC regulation - neither matches the 1N4112's combination of low-noise, high-reliability Zener performance in harsh environments.

Availability

1N4112 is available at Aetrix Electronics and suitable for aerospace power regulation, test equipment reference design, and industrial sensor signal conditioning requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for 1N4112 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 analog and mixed-signal components for aerospace, defense, and industrial markets.

The 1N4112 belongs to Microsemi's legacy MIL-qualified Zener diode family designed specifically for precision voltage regulation in mission-critical systems where parameter stability, radiation tolerance, and long-term reliability are non-negotiable.

FAQ

What is the Zener voltage tolerance for the 1N4112?

The 1N4112 has a nominal Zener voltage of 18.0 V with a standard tolerance of ±5% at 250 mA test current, as specified in the Electrical Characteristics table on page 3 of the T4-LDS-0245-2 datasheet. This tolerance applies to the commercial and mil-qualified versions unless otherwise marked with C (±2%) or D (±1%) suffixes.

Is the 1N4112 suitable for surface-mount applications?

No - the standard 1N4112 is supplied in the axial-leaded DO-35 (DO-204AH) glass package. Surface-mount variants exist under different part numbers: 1N4112UR-1 in DO-213AA and 1PMT4112 in DO-216, but the base 1N4112 requires through-hole mounting with 3/8-inch lead length for thermal performance compliance.

What is the maximum reverse leakage current for the 1N4112?

The maximum reverse leakage current (I_R) for the 1N4112 is 0.05 µA at a reverse voltage (V_R) of 13.7 V, measured at 25 °C. This ultra-low leakage supports use in battery-powered or high-impedance sensing circuits where standby current must be minimized.

Does the 1N4112 require heatsinking in normal operation?

No external heatsink is required for the 1N4112 at ambient temperatures ≤50 °C and power dissipation ≤500 mW. Its thermal resistance junction-to-lead is 250 °C/W with 3/8-inch lead length; however, PCB copper area and trace width significantly affect actual thermal performance per Figure 2 derating curve.

How does the temperature coefficient of the 1N4112 impact circuit design?

The 1N4112 has a temperature coefficient of +0.090 %/°C, meaning its Zener voltage increases by approximately 16.2 mV per °C rise above 25 °C. Designers must account for this drift in precision references - especially in unregulated environments - using compensation networks or selecting tighter-tolerance variants if needed.