Microchip Technology 1N1124R

Overview

1N1124R from Microsemi is a high-reliability glass-passivated power rectifier diode rated for 200 V peak repetitive reverse voltage (V_RWM), 3.3 A average forward current (I_F), and 25 A surge current (I_FSM), designed for ruggedized DC power conversion in military-grade power supplies and avionics rectification circuits.

For engineers reviewing the 1N1124R datasheet, 1N1124R pinout, 1N1124R application, or 1N1124R equivalent, key selection criteria include its DO-203AA (DO-4) stud-mount package, 2.0 °C/W junction-to-case thermal resistance, MIL-PRF-19500/260 qualification, and reverse leakage performance of ≤5 μA at 200 V and 25°C.

Technical Context

This axial-leaded, stud-mounted silicon rectifier uses glass-to-metal seal construction and glass-passivated die for enhanced moisture resistance and long-term reliability under thermal cycling. It operates across –65°C to +150°C case temperature range with storage up to +200°C.

The device exhibits forward voltage drop of 2.2 V at 10 A and 25°C, and reverse leakage remains ≤200 μA at 200 V and 150°C - critical for high-temperature power supply hold-up and field-deployed systems where thermal derating is essential.

Key Specifications

Pinout & Package

Package: DO-203AA (DO-4), stud-mounted metal case with threaded anode terminal and cathode stud or flange. Anode is electrically connected to the metal case; cathode is isolated via insulated mounting hardware.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-reliability power rectifier applications.

Compared with 1N1124R, 1N1124A offers identical electrical ratings but standard polarity, while 1N3649R extends reverse voltage capability to 800 V without changing footprint or thermal behavior - enabling voltage-scaling upgrades within existing mechanical constraints.

Availability

1N1124R is available at Aetrix Electronics and suitable for avionics power supplies, military radar transmitter supplies, and spacecraft power distribution requiring stable component supply and full MIL-PRF-19500/260 compliance.

Supply support for 1N1124R 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) designs high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial applications.

The 1N1124R belongs to Microsemi's legacy high-reliability discrete rectifier product line, engineered specifically for mission-critical power conversion where long-term stability, hermetic packaging, and MIL-standard qualification are mandatory.

FAQ

What is the polarity configuration of the 1N1124R?

The 'R' suffix in 1N1124R indicates reversed polarity: the metal case is the anode, and the insulated stud or flange is the cathode. This configuration allows direct anode connection to chassis or heatsink while keeping the cathode electrically isolated - critical for grounded-cathode rectifier topologies. Always verify polarity against schematic symbols before integration, as misorientation causes immediate short-circuit failure. The 1N1124R must be mounted using insulating hardware to preserve cathode isolation.

Does the 1N1124R require derating at elevated temperatures?

Yes, the 1N1124R must be thermally derated above +25°C ambient. Its average forward current drops linearly from 3.3 A at T_C = 150°C to zero at ~175°C case temperature. Engineers must calculate actual case temperature using R_θJC = 2.0 °C/W and system-level R_θCA, then apply manufacturer-provided derating curves. Failure to derate risks thermal runaway due to increased I_R and reduced V_F threshold at high junction temperatures.

Is the 1N1124R compliant with RoHS or REACH?

The 1N1124R is not RoHS-compliant due to its lead-based solder and legacy MIL-spec construction; it contains lead per exemption 7a (high-melting-temperature solders) and is intended for exempted defense/aerospace applications. REACH SVHC screening confirms no substances above threshold, but full compliance documentation is unavailable. For commercial or consumer designs, consult Aetrix Electronics for RoHS-compliant alternatives with equivalent performance.

Can the 1N1124R be used in parallel configurations?

No, the 1N1124R is not recommended for parallel operation due to inherent forward voltage mismatch between units, which causes current imbalance and potential thermal runaway. Even matched lots exhibit ±0.15 V V_F variation at 10 A. If higher current is needed, select a single higher-rated rectifier (e.g., 1N1126R) or redesign with active current-sharing circuitry - never rely on paralleling discrete 1N1124R units without external balancing resistors or active control.

What mechanical mounting torque is specified for the 1N1124R stud terminal?

The 1N1124R DO-203AA package specifies a maximum mounting torque of 15 inch-pounds applied to the 10-32NF-2B nut assembled on the threaded anode stud. Exceeding this torque risks thread deformation, case cracking, or compromised glass-to-metal seal integrity - directly violating MIL-PRF-19500/260 mechanical test requirements. Use calibrated torque tools and verify thread engagement depth per Note #5 (within 2.5 threads of seating plane) during assembly.