Microchip Technology 1N988A

Overview

1N988A from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 130 V nominal Zener voltage with ±10% tolerance, 0.95 mA Zener test current, and 1100 Ω dynamic impedance at I_ZT. It operates across –65 °C to +175 °C and regulates voltage in low-power reference and protection circuits.

For engineers reviewing the 1N988A datasheet, 1N988A pinout, 1N988A application, or 1N988A equivalent, key selection criteria include its 130 V regulation level, ±10% tolerance (A suffix), 0.95 mA test current, 1100 Ω Zener impedance, and DO-35 glass-body packaging suitable for through-hole voltage clamping and precision biasing.

Technical Context

The 1N988A functions as a two-terminal reverse-biased voltage reference, maintaining stable 130 V regulation over a broad operating current range (IZK = 0.25 mA, IZM = 2.7 mA) and temperature extremes (–65 °C to +175 °C). Its Zener impedance of 1100 Ω at 0.95 mA reflects moderate dynamic resistance suited for non-critical stabilization.

It features a cathode band marking, tin-lead or RoHS-compliant matte-tin plating, and hermetically sealed glass DO-35 construction. Thermal resistance is 250 °C/W junction-to-lead (3/8″ lead length) and 310 °C/W junction-to-ambient on FR4 with defined copper pad geometry.

Key Specifications

Pinout & Package

Package: DO-35 (DO-204AH), hermetically sealed axial-lead glass body, 0.2 g weight, cathode indicated by colored band. Tin-lead or RoHS-compliant matte-tin plating, solderable per MIL-STD-750 Method 2026.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N988A, the 1N988B offers tighter voltage control but same thermal and mechanical behavior, while MMBZ5263BLT1G sacrifices power rating and impedance performance for SMT compatibility - neither is pin-compatible, and both require layout or thermal redesign.

Availability

1N988A is available at Aetrix Electronics and suitable for industrial power supply reference, overvoltage protection circuit, and legacy system voltage monitor applications requiring stable component supply and long-lifecycle support.

Supply support for 1N988A 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 analog, RF, and radiation-hardened components for aerospace, defense, and industrial markets.

The 1N957B–1N992B series was designed specifically for ruggedized, through-hole Zener regulation in harsh-environment systems where wide temperature range, ESD immunity, and hermetic sealing are mandatory.

FAQ

What is the Zener voltage tolerance for 1N988A?

The 1N988A has a nominal Zener voltage of 130 V with ±10% tolerance, as indicated by the "A" suffix per Microsemi's documentation. This means the actual measured V_Z falls between 117 V and 143 V when tested at 0.95 mA and 25 °C. The tolerance is guaranteed across the full operating temperature range of –65 °C to +175 °C, making 1N988A suitable for applications where moderate regulation accuracy is acceptable.

Can 1N988A be used in surface-mount designs?

No, the 1N988A is packaged exclusively in the axial-lead DO-35 (DO-204AH) glass body and is not compatible with surface-mount assembly. For SMT equivalents, Microsemi offers the MLL988B in DO-213AA (MELF) package, or third-party alternatives like MMBZ5263BLT1G in SOT-23 - but these differ in power rating, impedance, and thermal behavior. Direct substitution of 1N988A into an SMT footprint is not feasible without board redesign.

What is the maximum steady-state power dissipation for 1N988A?

The 1N988A is rated for 500 mW steady-state power dissipation at lead temperature (T_L) below 50 °C, measured 3/8″ from the body. When mounted on FR4 with specified copper pads, its derated power is 480 mW at 25 °C ambient. Power must be reduced linearly above 50 °C per the curve in Figure 1 of the datasheet; at 75 °C lead temperature, the safe limit drops to 400 mW, corresponding to I_ZM = 2.7 mA.

Does 1N988A have radiation-hardened characteristics?

Yes, the 1N988A exhibits inherent radiation hardness as documented in Microsemi MicroNote 050. Its DO-35 glass-body construction and silicon process yield tolerance to total ionizing dose (TID) levels suitable for non-military space-adjacent and high-altitude industrial applications. While not certified to MIL-PRF-19500 Class H or Q levels, its behavior under gamma irradiation is characterized and stable - a key reason it remains in demand for legacy avionics and downhole equipment.

How is polarity identified on the 1N988A package?

The 1N988A uses a cathode band - a single painted or etched ring near one end of the glass body - to indicate the cathode terminal. During Zener operation, the banded end must be held at a higher potential than the opposite (anode) end. Forward voltage is ≤1.3 V at 200 mA, confirming standard silicon diode behavior; reverse leakage is specified as 5 μA at 104 V, verifying correct band orientation during functional testing.