Microchip Technology 1N968B

Overview

1N968B from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 20 V nominal Zener voltage with ±5% tolerance, 6.2 mA Zener test current, 750 Ω maximum Zener impedance at I_ZT, and +0.086 %/°C temperature coefficient. It regulates voltage in low-power reference and protection circuits across industrial control and power supply feedback paths.

For engineers reviewing the 1N968B datasheet, 1N968B pinout, 1N968B application, or 1N968B equivalent, key selection criteria include its 20 V regulation point, 0.5 W steady-state power rating at 50 °C lead temperature, DO-35 mechanical compatibility, and JEDEC-registered B-suffix tolerance specification.

Technical Context

The 1N968B operates as a reverse-biased voltage reference device with a sharp breakdown knee verified by dual-point Zener impedance measurement per MicroNote 202. Its regulation stability relies on metallurgical bond construction (optional with "-1" suffix) and hermetically sealed glass DO-35 packaging enabling operation from –65 °C to +175 °C.

Thermal performance is defined by 250 °C/W junction-to-lead resistance at 10 mm lead length and 310 °C/W junction-to-ambient on FR4 with specified copper pad geometry. Forward voltage remains ≤1.1 V at 200 mA, confirming low-conduction-loss capability for bidirectional clamping use cases.

Key Specifications

Pinout & Package

Package: DO-35 (DO-204AH), hermetically sealed axial-lead glass body, cathode indicated by band; terminals plated with tin-lead or RoHS-compliant matte tin 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 1N968B, the 1N4742A offers higher surge robustness but demands PCB layout change, while the BZX55C20 delivers tighter regulation at low current yet lacks the positive tempco needed for complementary drift cancellation in precision references.

Availability

1N968B is available at Aetrix Electronics and suitable for industrial power supplies, sensor signal conditioning, overvoltage protection circuits, and precision voltage reference designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 1N968B 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 and mixed-signal components for aerospace, defense, and industrial markets.

The 1N968B belongs to Microsemi's legacy JEDEC-registered 1N957B–1N992B Zener series, engineered for stable voltage regulation in harsh-environment applications where hermetic sealing, radiation tolerance, and wide temperature operation are mandatory.

FAQ

What is the Zener voltage tolerance for 1N968B?

The 1N968B has a nominal Zener voltage of 20 V with a ±5% tolerance, as indicated by the "B" suffix per JEDEC registration. This means the actual measured V_Z at 6.2 mA test current falls between 19.0 V and 21.0 V at 25 °C. The tolerance is guaranteed across the full operating temperature range of –65 °C to +175 °C, consistent with Microsemi's DO-35 series specifications.

Can 1N968B be used in surface-mount designs?

No, the 1N968B is packaged exclusively in the through-hole DO-35 (DO-204AH) axial-lead glass case. For surface-mount equivalents, Microsemi offers the MLL968B in DO-213AA (MELF) package - same 20 V ±5% rating and electrical specs, but requiring reflow-compatible layout. The 1N968B itself must be mounted axially with 10 mm lead length for thermal compliance.

What is the maximum power dissipation for 1N968B at room temperature?

The 1N968B is rated for 0.5 W steady-state power dissipation at a lead temperature (T_L) below 50 °C, measured 10 mm from the body. When mounted on an FR4 PCB with specified copper pads (4 mm²), its derated power drops to 0.48 W at 25 °C ambient. Exceeding these limits risks thermal runaway due to its +0.086 %/°C positive tempco.

Does 1N968B require external ESD protection?

No, the 1N968B is nonsensitive to ESD per MIL-STD-750 Method 1020, meaning it withstands typical handling and assembly electrostatic discharges without degradation. Its glass DO-35 construction and internal metallurgy eliminate the need for additional TVS diodes or RC filters in most industrial environments - a key advantage over non-qualified Zeners.

How does the temperature coefficient affect 1N968B in precision circuits?

The +0.086 %/°C temperature coefficient of 1N968B causes its Zener voltage to increase by approximately 17.2 mV per °C rise. In precision references, this drift must be compensated - for example, by pairing with a forward-biased diode exhibiting negative tempco. At 85 °C ambient, V_Z rises to ~21.45 V, which is fully characterized in Microsemi's derating curves (Figure 1).