Microchip Technology 1N4370A-1/TR

Overview

1N4370A-1/TR from Microsemi is a 500 mW, 2.4 V ±5% axial-leaded silicon Zener diode in DO-35 (DO-204AH) glass package, qualified to JANTXV level per MIL-PRF-19500/127, with 30 Ω dynamic impedance at 20 mA and -0.085 %/°C temperature coefficient - used for precision voltage regulation in military power supplies and analog reference circuits.

For engineers reviewing the 1N4370A-1/TR datasheet, 1N4370A-1/TR pinout, 1N4370A-1/TR application, or 1N4370A-1/TR equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (250 °C/W junction-to-lead), reverse leakage (100 µA @ 1.0 V), RoHS compliance status, and MIL-qualified reliability grading.

Technical Context

This device operates as a two-terminal voltage reference in reverse-bias breakdown mode, delivering stable 2.4 V regulation across -65 °C to +175 °C ambient range. Its internal metallurgical bond ensures mechanical robustness under thermal cycling and shock, while low 30 Ω Zener impedance supports tight regulation under varying load currents.

The 1N4370A-1/TR exhibits negative temperature coefficient (-0.085 %/°C), making it suitable for temperature-compensated references when paired with positive-TC components. It is rated for 155 mA maximum Zener current and features minimal capacitance and ESD immunity per MIL-STD-750 method 1020.

Key Specifications

Pinout & Package

Hermetically sealed axial-leaded DO-35 (DO-204AH) glass package with cathode indicated by band; leads are tin-lead or RoHS-compliant matte-tin plated and 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 1N4370A-1/TR, the 1N4370AUR-1 offers identical regulation performance in a rugged MELF package ideal for high-vibration environments, while the 1N5221B provides equivalent voltage specs at lower cost and qualification level - enabling trade-offs between reliability assurance, assembly method, and procurement constraints.

Availability

1N4370A-1/TR is available at Aetrix Electronics and suitable for avionics power conditioning, military radio reference supply, and spacecraft sensor biasing requiring stable component supply with full MIL-qualified traceability and long-term obsolescence management.

Supply support for 1N4370A-1/TR 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 Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and defense-grade analog and mixed-signal components.

The 1N4370A-1/TR belongs to Microsemi's legacy MIL-PRF-19500/127-qualified Zener diode family, designed specifically for voltage reference and regulation in mission-critical aerospace, defense, and industrial control systems where long-term stability and environmental resilience are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N4370A-1/TR?

The 1N4370A-1/TR has a nominal Zener voltage of 2.4 V with a tolerance of ±5%, as indicated by the "A" suffix in its nomenclature per JEDEC standards. This tolerance applies at the specified test current of 20 mA and ambient temperature of 25 °C. The device maintains this specification across its qualified operating temperature range of -65 °C to +175 °C when used within its power and thermal limits.

Is the 1N4370A-1/TR RoHS compliant?

Yes, the 1N4370A-1/TR is RoHS compliant, as confirmed by its "TR" tape-and-reel suffix and documentation in Microsemi's T4-LDS-0288 datasheet. RoHS compliance applies to the commercial-grade version only; the same part number with JAN/JANTX/JANTXV prefixes retains leaded terminations per MIL-PRF-19500 requirements. All RoHS-compliant units use annealed matte-tin plating and meet solderability per MIL-STD-750 method 2026.

What does the "-1" suffix mean in 1N4370A-1/TR?

The "-1" suffix in 1N4370A-1/TR denotes the metallurgically bonded construction variant, distinguishing it from earlier wire-bonded versions. This structural enhancement improves thermal cycling endurance and mechanical shock resistance. The "TR" suffix separately indicates tape-and-reel packaging per EIA-296 standard. Both suffixes appear together in the full orderable part number to specify construction and packaging simultaneously.

What is the maximum Zener current rating for the 1N4370A-1/TR?

The 1N4370A-1/TR has a maximum Zener current (I_ZM) rating of 155 mA, derived from its 500 mW power dissipation limit at 2.4 V (P = V × I → I = 0.5 W / 2.4 V ≈ 208 mA), adjusted for dynamic impedance heating and thermal equilibrium effects per Note 4 in the Electrical Characteristics table. This value assumes operation at T_L = 50 °C with 0.375″ lead length; derating applies above that temperature.

How is polarity marked on the 1N4370A-1/TR package?

The 1N4370A-1/TR uses a cathode band marking on the glass DO-35 body to indicate polarity: the banded end is the cathode and must be held at a higher potential than the unbanded (anode) end for proper Zener regulation. This marking is visible as a distinct opaque ring near one lead exit point and is consistent with JEDEC DO-35 mechanical standards. Polarity verification is critical - reverse connection results in forward conduction (~1.1 V drop) rather than regulation.