Microchip Technology 1N970A

Overview

1N970A from Microsemi is a silicon 500 mW axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 24 V nominal Zener voltage with ±10% tolerance (A suffix), 5.2 mA Zener test current, 750 Ω maximum Zener impedance at I_ZT, and −65 °C to +175 °C operating temperature range. It serves as a precision voltage reference or shunt regulator in low-power analog circuits, power supply feedback paths, and overvoltage protection stages.

For engineers reviewing the 1N970A datasheet, 1N970A pinout, 1N970A application, or 1N970A equivalent, key selection considerations include its 24 V regulation point, ±10% voltage tolerance, 750 Ω dynamic impedance, thermal resistance of 250 °C/W (junction-to-lead), and DO-35 glass-body construction suitable for high-reliability industrial and aerospace environments.

Technical Context

The 1N970A operates as a reverse-biased shunt regulator, maintaining stable 24 V output across a defined current range (5.2 mA I_ZT, up to 15 mA I_ZM) while exhibiting a positive temperature coefficient of +0.088 %/°C. Its Zener knee is characterized by 750 Ω impedance at test current and 0.25 mA leakage at 18.2 V reverse bias.

Designed for axial-leaded through-hole mounting, it features hermetically sealed glass encapsulation, tin-lead or RoHS-compliant matte-tin plating, cathode band polarity marking, and JEDEC-registered compliance. It is not ESD-sensitive per MIL-STD-750 Method 1020 and exhibits minimal capacitance per Figure 3.

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 1N970B and 1N5242B, the 1N970A offers cost-optimized ±10% regulation with higher dynamic impedance-suited for static reference or clamping where precision and fast transient response are secondary to ruggedness and legacy compatibility.

Availability

1N970A is available at Aetrix Electronics and suitable for industrial power supplies, avionics subsystems, and test equipment calibration requiring stable component supply with JEDEC-registered consistency and DO-35 mechanical compatibility.

Supply support for 1N970A 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 1N970A belongs to Microsemi's legacy 1N957B–1N992B DO-35 Zener series, engineered for robust voltage regulation in extreme-temperature and high-integrity systems where long-term parametric stability and JEDEC standardization are mandatory.

FAQ

What is the Zener voltage tolerance for 1N970A?

The 1N970A has a nominal Zener voltage of 24 V with a ±10% tolerance, as indicated by the "A" suffix per Microsemi's documentation. This means the actual measured Zener voltage at 5.2 mA test current falls between 21.6 V and 26.4 V at 25 °C. The tolerance is wider than the ±5% "B" variant but supports cost-sensitive applications where tight regulation is not required.

What is the maximum power dissipation for 1N970A under typical PCB mounting conditions?

The 1N970A is rated for 500 mW at lead temperature < 50 °C (measured 3/8″ from body), but derates to 480 mW at ambient temperature < 25 °C when mounted on FR4 with 1 oz copper, 4 mm² pads, and 1 mm × 25 mm traces. Its thermal resistance is 310 °C/W junction-to-ambient under those conditions, defining safe continuous operation limits.

Does 1N970A have RoHS-compliant packaging options?

Yes - Microsemi offers RoHS-compliant versions of the 1N970A by adding the "e3" suffix (e.g., 1N970Ae3), featuring annealed matte-tin plating instead of traditional tin-lead. These devices meet JEDEC and RoHS Directive requirements while retaining identical electrical specifications, DO-35 mechanical form, and thermal performance.

How does the temperature coefficient of 1N970A affect its regulation accuracy over temperature?

The 1N970A has a temperature coefficient of +0.088 %/°C, meaning its Zener voltage increases by approximately 21.1 mV per °C rise in junction temperature. Over a −55 °C to +125 °C range, this results in ~1.9 V total drift. System designs must compensate for this if sub-1% absolute accuracy is required across temperature.

Can 1N970A be used as a direct replacement for 1N970B in existing designs?

No - while both share identical 24 V nominal voltage, DO-35 package, and thermal ratings, the 1N970A (±10%) and 1N970B (±5%) differ in voltage tolerance and are not drop-in replacements where tight regulation is specified. Substitution requires validation of system-level output tolerance margins and potential recalibration of feedback networks.