Microchip Technology 1N4992US/TR

Overview

1N4992US/TR from Microsemi is a surface-mount, voidless-hermetically-sealed glass Zener diode rated for 5 W power dissipation at T_EC = 140 °C, with nominal Zener voltage 270 V ±5%, dynamic impedance 800 Ω at I_ZT = 5 mA, and operating junction temperature range −65 °C to +175 °C. It serves as a precision voltage reference or overvoltage clamp in high-reliability military and aerospace power regulation circuits.

For engineers reviewing the 1N4992US/TR datasheet, 1N4992US/TR pinout, 1N4992US/TR application, or 1N4992US/TR equivalent, this part is selected for ultra-stable Zener regulation under extreme thermal stress, radiation-hardened environments, and long-life sealed-system designs where hermetic integrity and low leakage (<2 μA at 206 V) are mandatory.

Technical Context

This device belongs to the MIL-PRF-19500/356-qualified 1N4954US–1N4996US family, featuring triple-layer passivation and Category I internal metallurgical bonds. Its voidless-glass construction ensures zero internal delamination risk and immunity to moisture-induced failure modes.

It operates with a temperature coefficient of +0.120 %/°C at I_ZT, exhibits 25 V voltage regulation (ΔV_Z) between 10% and 50% of I_ZM, and maintains ≤2 μA reverse leakage at 206 V - enabling stable clamping across wide temperature excursions without derating penalties typical of plastic-packaged Zeners.

Key Specifications

Pinout & Package

Package: Hermetically sealed voidless hard glass case with tungsten slugs; end caps are copper with Sn/Pb finish; polarity indicated by cathode band; weight 539 mg; EIA-481-B tape & reel compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4992US/TR, the axial 1N4992US requires PCB redesign and lacks SMT scalability, while SMZ270A trades 5 W power handling and radiation tolerance for lower cost and smaller footprint - making 1N4992US/TR irreplaceable in mission-critical sealed systems.

Availability

1N4992US/TR is available at Aetrix Electronics and suitable for aerospace power bus clamping, satellite payload voltage referencing, and military avionics overvoltage protection requiring stable component supply across extended temperature and radiation environments.

Supply support for 1N4992US/TR 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) specializes in high-reliability analog and mixed-signal semiconductors for defense, aerospace, and industrial markets.

The 1N49xxUS series was engineered specifically for MIL-PRF-19500/356-compliant Zener regulation in hermetically sealed, radiation-intensive, and thermally extreme applications - prioritizing long-term parametric stability over cost or size.

FAQ

What is the maximum continuous Zener current for 1N4992US/TR?

The maximum continuous Zener current I_ZM for 1N4992US/TR is 1.4 A at T_EC = 140 °C, derating linearly to zero at 175 °C. This value is derived from its 5 W power rating and 270 V nominal Zener voltage, ensuring safe operation in high-voltage regulation circuits without thermal runaway under steady-state conditions. The 1N4992US/TR maintains this rating across its full −65 °C to +175 °C junction temperature range.

Does 1N4992US/TR require external ESD protection during PCB assembly?

No, 1N4992US/TR does not require external ESD protection during PCB assembly. It is inherently nonsensitive to electrostatic discharge per MIL-STD-750 Method 1020, withstanding ≥4 kV human-body-model (HBM) events. This eliminates the need for additional TVS diodes or grounding straps in SMT handling, simplifying manufacturing flow while preserving reliability of the 1N4992US/TR in final assemblies.

Is the 1N4992US/TR qualified for space applications?

Yes, 1N4992US/TR is qualified for space applications under MIL-PRF-19500/356 at JAN/JANTX levels, including full lot acceptance testing, burn-in, and radiation hardness assurance per MicroNote 050 (TID >100 krad(Si)). Its voidless-glass hermetic seal and Category I metallurgical bond meet NASA EEE-INST-002 and ESA ESCC 3401 requirements for Class S missions, confirming suitability for use in 1N4992US/TR-based power systems aboard satellites and deep-space probes.

What is the reverse leakage current specification for 1N4992US/TR at 206 V?

The reverse leakage current I_R for 1N4992US/TR is specified as ≤2 μA at V_R = 206 V and T_A = 25 °C. This low leakage ensures minimal standby power loss in high-impedance bias networks and preserves signal integrity in precision reference applications - a critical performance attribute confirmed across all production lots of 1N4992US/TR and maintained over its operational lifetime.

Can 1N4992US/TR be used in place of 1N4992 (non-US) in new designs?

No, 1N4992US/TR cannot be directly substituted for non-US variants like 1N4992 (DO-41 axial) without layout and thermal validation. While electrical parameters match, the 1N4992US/TR uses an "E" (D-5B) surface-mount glass package with different thermal resistance (7 °C/W junction-to-end-cap), solder-reflow profile, and mechanical mounting requirements. New designs must use 1N4992US/TR exclusively with its documented SMT pad layout and reflow specifications to ensure reliability of the 1N4992US/TR in production.