Microchip Technology 1N984A

Overview

1N984A from Microsemi is a silicon 500 mW axial-lead Zener diode with nominal Zener voltage 91 V, ±10% tolerance (A suffix), 400 Ω maximum Zener impedance at 1.4 mA test current, and −65 °C to +175 °C operating temperature range. It regulates voltage in low-power reference and protection circuits where stable breakdown under reverse bias is required.

For engineers reviewing the 1N984A datasheet, 1N984A pinout, 1N984A application, or 1N984A equivalent, key selection criteria include its 91 V nominal Zener voltage, DO-35 glass package with cathode band marking, 400 Ω dynamic impedance, and suitability for overvoltage clamping in industrial power supplies and sensor signal conditioning.

Technical Context

The 1N984A operates as a reverse-biased voltage reference device, maintaining regulation across 4.1 mA DC Zener current (IZM) and up to 21 A surge current (IZSM) for 1/120 sec pulses. Its Zener knee is characterized at 1.4 mA test current (IZT), with 0.25 mA minimum knee current (IZK) and 5 μA reverse leakage at 73 V (75% of VZ).

Thermal performance is defined for 3/8″ lead length: 250 °C/W junction-to-lead resistance and 400 mW max power dissipation at TL < 75 °C. The device exhibits +0.099 %/°C temperature coefficient and inherent radiation hardness per MicroNote 050.

Key Specifications

Pinout & Package

Package: DO-35 (DO-204AH), hermetically sealed axial-lead glass body, cathode indicated by colored 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 1N984B and MMBZ5262B, the 1N984A provides lower-cost axial-lead implementation with wider tolerance and higher thermal robustness (−65 °C to +175 °C), making it optimal for industrial and military applications where board-level ruggedness outweighs precision or miniaturization needs.

Availability

1N984A is available at Aetrix Electronics and suitable for industrial power supply regulation, overvoltage protection circuits, and sensor signal conditioning requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 1N984A 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) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and high-voltage analog components for aerospace, defense, and industrial markets.

The 1N957B–1N992B series was designed specifically for ruggedized voltage regulation in mission-critical systems where long-term stability, wide temperature operation, and ESD insensitivity are essential.

FAQ

What is the nominal Zener voltage and tolerance of the 1N984A?

The 1N984A has a nominal Zener voltage of 91 V with ±10% tolerance, as indicated by the "A" suffix per JEDEC standard. This means the actual breakdown voltage falls between 81.9 V and 100.1 V at 1.4 mA test current and 25 °C ambient. The tolerance reflects manufacturing spread optimized for cost-sensitive industrial applications where tight regulation is not required.

What package type does the 1N984A use and how is polarity marked?

The 1N984A uses the DO-35 (DO-204AH) axial-lead hermetically sealed glass package. Polarity is marked by a visible cathode band on the glass body; the banded end is the cathode and must be held at higher potential than the anode (non-banded end) during Zener operation. This marking aligns with JEDEC-standard visual identification for through-hole Zener diodes.

What is the maximum steady-state power dissipation for the 1N984A?

The 1N984A is rated for 500 mW maximum steady-state power dissipation at lead temperature (TL) < 50 °C with 3/8″ (10 mm) lead length from the body. Derating begins above 50 °C, reaching 400 mW at TL = 75 °C. When mounted on FR4 PCB with 4 mm² copper pads, max power drops to 480 mW at TA < 25 °C due to higher junction-to-ambient thermal resistance (310 °C/W).

How does the 1N984A perform under surge conditions?

The 1N984A supports a maximum surge current (IZSM) of 21 A for a 1/120 second pulse (equivalent to 8.33 ms half-sine wave). This capability enables reliable transient suppression in power rails exposed to lightning-induced surges or inductive switching spikes. Surge testing follows JEDEC-standard waveform definitions and validates robustness without parametric shift or catastrophic failure.

Is the 1N984A suitable for high-temperature environments?

Yes, the 1N984A is rated for operation from −65 °C to +175 °C, making it suitable for under-hood automotive, downhole oil/gas, and aerospace applications. Its glass DO-35 package and internal metallurgical construction maintain parameter stability across this full range. Thermal resistance data (250 °C/W junction-to-lead) and derating curves confirm predictable performance at elevated temperatures without derating beyond published limits.