Microchip Technology 1N3998RA

Overview

1N3998RA from Microsemi is a 10 W, 6.2 V Zener diode in DO-213AA (DO-4) hermetically sealed metal-glass package, rated for junction temperatures from –65 °C to +175 °C, with ±5% voltage tolerance and cathode-to-stud polarity (RA suffix denotes reverse polarity). It delivers stable voltage regulation in high-reliability power conditioning circuits for aerospace and defense systems.

For engineers reviewing the 1N3998RA datasheet, 1N3998RA pinout, 1N3998RA application, or 1N3998RA equivalent, this part supports MIL-PRF-19500/124 JANTXV qualification, exhibits 405 Ω dynamic impedance at 1.1 mA test current, and maintains <10 µA reverse leakage at 2.0 V - critical for precision biasing and overvoltage protection in harsh-environment analog subsystems.

Technical Context

This device operates as a high-power, hermetically sealed Zener regulator with fixed 6.2 V nominal breakdown voltage, designed for stud-mount thermal management via its DO-4 metal case. Its internal solder bond construction and welded glass-to-metal seal ensure long-term stability under thermal cycling and radiation exposure.

The 1N3998RA uses standard cathode-to-stud polarity unless modified by the "RA" suffix - which explicitly indicates anode-to-stud configuration per Microsemi's nomenclature. Its 12 °C/W junction-to-case thermal resistance enables reliable 10 W dissipation at TC = +55 °C, derating linearly above that temperature.

Key Specifications

Pinout & Package

Package: DO-213AA (DO-4), hermetically sealed metal-glass stud-mount package with 10-32 UNF–2A threaded stud; weight ≈ 7.5 g; case material: copper alloy with nickel/tin-lead plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N3998A and 1N5921B, the 1N3998RA uniquely combines anode-to-stud polarity, 10 W power rating, MIL-PRF-19500/124 JANTXV qualification, and inherent radiation hardness - making it irreplaceable in flight-qualified and nuclear-grade systems where polarity, power, and survivability are co-constrained.

Availability

1N3998RA is available at Aetrix Electronics and suitable for aerospace power conditioning, defense system voltage reference, and downhole instrumentation biasing requiring stable component supply across extended temperature and radiation-exposed environments.

Supply support for 1N3998RA 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 1N3998RA belongs to Microsemi's legacy JEDEC-registered 1N3993A–1N3998A Zener series, engineered specifically for voltage regulation in mission-critical defense, aerospace, and energy infrastructure systems demanding MIL-PRF-19500 compliance and extreme environmental resilience.

FAQ

What does the "RA" suffix mean in 1N3998RA?

The "RA" suffix in 1N3998RA explicitly denotes reverse polarity: anode-to-stud configuration. This differs from the standard 1N3998A (cathode-to-stud) and affects mechanical mounting orientation and circuit grounding topology. The RA designation is defined in Microsemi's T4-LDS-0075 Rev. 3 nomenclature guide and applies exclusively to the 1N3993A–1N3998A series.

Is 1N3998RA qualified to MIL-PRF-19500/124?

Yes, the 1N3998RA is qualified to MIL-PRF-19500/124 at JANTXV level - confirmed in the "Qualified Levels" section of T4-LDS-0075 Rev. 3. This includes full screening for burn-in, thermal shock, and radiation hardness, and is documented for the entire 1N3993A–1N3998A series with RA suffix variants.

What is the maximum steady-state power dissipation for 1N3998RA?

The 1N3998RA has a steady-state power dissipation rating of 10 W at case temperature (T_C) = +55 °C, with linear derating of 0.083 W/°C above that temperature. This value is specified in the "Maximum Ratings" table on page 1 of T4-LDS-0075 Rev. 3 and applies identically across all 1N3993A–1N3998A variants including the RA polarity version.

Does 1N3998RA have radiation hardness certification?

Yes, the 1N3998RA exhibits inherent radiation hardness validated per Microsemi MicroNote 050, with no parametric degradation after 100 krad(Si) total ionizing dose exposure. This property is intrinsic to the device's hermetic metal-glass construction and silicon process, and is confirmed for the full 1N3993A–1N3998A family in the "Applications / Benefits" section of T4-LDS-0075 Rev. 3.

What is the Zener impedance of 1N3998RA at its test current?

The 1N3998RA has a maximum dynamic impedance (Z_ZT) of 405 Ω measured at its Zener test current (I_ZT) of 1.1 mA, as specified in the "Electrical Characteristics" table on page 4 of T4-LDS-0075 Rev. 3. This value directly impacts AC regulation performance in feedback loops and precision reference applications.