Microchip Technology 1N748C

Overview

1N748C from Microsemi is a 500 mW, 3.9 V ±2% tolerance silicon Zener diode in DO-35 glass axial package, qualified to JANTX level per MIL-PRF-19500/127, with dynamic impedance of 20 Ω at 30 mA and temperature coefficient of –0.060 %/°C, used for precision voltage regulation in military power supply reference circuits.

For engineers reviewing the 1N748C datasheet, 1N748C pinout, 1N748C application, or 1N748C equivalent, key selection criteria include Zener voltage tolerance (±2%), junction-to-lead thermal resistance (250 °C/W), reverse leakage (≤2 µA at 1.0 V), maximum Zener current (100 mA), and RoHS compliance status (commercial grade only).

Technical Context

The 1N748C operates as a two-terminal voltage reference device, maintaining stable 3.9 V regulation across load and temperature variations via controlled avalanche breakdown. Its metallurgically bonded junction ensures long-term stability and radiation hardness per MicroNote 050.

It functions exclusively in reverse bias, with cathode identified by band; forward voltage is 1.1 V at 200 mA. Thermal derating follows linear curves: 500 mW at lead temperature ≤50 °C, zero at 175 °C; on PCB, 400 mW at ambient ≤55 °C, zero at 175 °C.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) hermetically sealed axial-leaded glass package with cathode indicated by colored band; leads are tin-lead or RoHS-compliant matte-tin plated (commercial grade only); weight ≈0.2 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N748A-1 and BZX55-C3V9, the 1N748C delivers superior voltage accuracy (±2%) and assured reliability for mission-critical systems, while retaining identical physical form and thermal behavior-making it the preferred choice when regulation precision and environmental ruggedness are jointly required.

Availability

1N748C is available at Aetrix Electronics and suitable for military power supply reference, aerospace voltage monitoring, and industrial sensor excitation requiring stable component supply across extended temperature and radiation environments.

Supply support for 1N748C 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 analog and mixed-signal components for aerospace, defense, and industrial markets.

The 1N748C belongs to Microsemi's legacy MIL-PRF-19500/127 qualified Zener diode family, designed specifically for precision voltage regulation in harsh-environment electronic systems where long-term stability and radiation tolerance are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N748C?

The 1N748C has a nominal Zener voltage of 3.9 V with a tolerance of ±2%, as indicated by the "C" suffix in its part number per Microsemi's nomenclature. This tighter tolerance is achieved through post-manufacturing screening and is distinct from the ±5% tolerance of the 1N748A-1 variant. The 1N748C maintains this specification at I_ZT = 30 mA and T_A = 25 °C, enabling higher-accuracy voltage references in critical analog circuits.

Is the 1N748C RoHS compliant?

The 1N748C is not RoHS compliant. Per Microsemi documentation, RoHS-compliant versions (e.g., with "e3" suffix) are available only for commercial-grade variants-not for JAN, JANTX, or JANTXV qualified parts like the 1N748C. The 1N748C uses traditional tin-lead plating on its leads to meet MIL-STD-750 solderability requirements and ensure reliability under thermal cycling stress typical in military applications.

What does the "C" in 1N748C signify?

The "C" in 1N748C denotes the Zener voltage tolerance code per Microsemi's part numbering scheme: "C" = ±2%, "A" = ±5%, and "D" = ±1%. It is not a package or revision indicator. This suffix directly corresponds to the electrical binning applied during final test, and appears in the Electrical Characteristics table on page 3 of T4-LDS-0288, confirming that 1N748C delivers 3.9 V regulation within ±2% at 30 mA.

Can the 1N748C be used in surface-mount designs?

No, the 1N748C is not a surface-mount device. It is packaged exclusively in the axial-leaded DO-35 (DO-204AH) glass case. While Microsemi offers MELF surface-mount equivalents (e.g., 1N748AUR-1 in DO-213AA), the 1N748C itself has no SMT variant. Its leaded construction requires through-hole mounting and thermal management via lead length (0.375″ minimum from body) rather than PCB copper area.

What is the maximum Zener current rating for the 1N748C?

The maximum Zener current (I_ZM) for the 1N748C is 100 mA, as specified in the Electrical Characteristics table on page 3 of T4-LDS-0288. This value assumes operation at 25 °C ambient and accounts for both power dissipation limits (500 mW) and dynamic impedance-induced voltage rise. At elevated temperatures, I_ZM must be reduced per the linear derating curve in Figure 1, reaching zero at 175 °C junction temperature.