Microchip Technology 1N988B

Overview

1N988B from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 130 V nominal Zener voltage at 0.95 mA test current, with ±5% tolerance (B suffix), +0.11%/°C temperature coefficient, and maximum 1100 Ω dynamic impedance at I_ZT. It regulates voltage in precision reference and overvoltage protection circuits operating from −65°C to +175°C.

For engineers reviewing the 1N988B datasheet, 1N988B pinout, 1N988B application, or 1N988B equivalent, this part serves as a stable, radiation-hardened, low-capacitance voltage reference in high-reliability analog power supplies, industrial sensor conditioning, and aerospace power management where wide temperature operation and JEDEC-registered performance are required.

Technical Context

The 1N988B operates as a reverse-biased voltage reference with a sharp breakdown knee, specified under JEDEC-standard test conditions: 20-second DC test current application, lead temperature controlled at 25°C ±2°C, and mounting clips positioned 0.375–0.500 inches from the glass body. Its Zener impedance is measured using a 60 Hz AC signal equal to 10% of I_ZT, ensuring stability across production lots.

Thermal design requires attention to junction-to-lead resistance (250°C/W at 3/8″ lead length) and derating above 50°C lead temperature. At 25°C ambient on FR4 with 4 mm² copper pads, it delivers 480 mW steady-state power; surge capability supports 13 mA square-wave pulses of 1/120 sec duration.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N988A and 1N988C, the 1N988B strikes a balance between cost and precision: its ±5% tolerance avoids the calibration overhead of the A-suffix while remaining more economical than the C-suffix's ±2% grade, making it optimal for mid-tier industrial power monitoring and sensor interfaces.

Availability

1N988B is available at Aetrix Electronics and suitable for high-reliability power supply reference, overvoltage protection, and aerospace sensor excitation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 1N988B 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 defense, aerospace, and industrial markets.

The 1N957B–1N992B series was designed specifically for ruggedized voltage regulation in mission-critical systems where JEDEC registration, wide temperature operation, and proven field reliability are mandatory.

FAQ

What is the Zener voltage tolerance for 1N988B?

The 1N988B has a nominal Zener voltage of 130 V with a ±5% tolerance, as indicated by the "B" suffix per JEDEC standard. This means the actual measured V_Z falls between 123.5 V and 136.5 V at 0.95 mA test current and 25°C. The tolerance is tighter than the A-suffix (±10%) but looser than the C-suffix (±2%), offering a balanced trade-off for industrial-grade designs.

Can 1N988B be used in surface-mount designs?

No, the 1N988B is packaged exclusively in the axial-lead DO-35 (DO-204AH) glass body and is not a surface-mount device. For SMT equivalents, Microsemi offers the MLL988B in DO-213AA (MELF) package - a direct functional counterpart with identical electrical specs but different mechanical form factor and soldering requirements.

What is the maximum power dissipation for 1N988B at 75°C lead temperature?

At a lead temperature of 75°C, the 1N988B is rated for 400 mW maximum power dissipation, corresponding to a DC Zener current limit of 2.7 mA. This value is derived from thermal derating curves in the datasheet and assumes 3/8″ lead length from the glass body. Exceeding this current risks thermal instability or parametric shift.

Is 1N988B compliant with RoHS requirements?

Yes, the RoHS-compliant version of 1N988B is designated as 1N988Be3, where the "e3" suffix indicates annealed matte-tin plating meeting EU RoHS Directive 2011/65/EU. Standard 1N988B uses tin-lead plating; both versions share identical electrical and thermal specifications except for termination chemistry.

How does the temperature coefficient affect 1N988B's regulation accuracy over temperature?

The 1N988B has a +0.11 %/°C temperature coefficient, meaning its Zener voltage increases by approximately 0.143 V per 10°C rise above 25°C. Over a −40°C to +85°C ambient range, this contributes up to ±1.43 V drift - a key factor in high-accuracy reference designs where external compensation or calibration may be required.