Taiwan Semiconductor Corporation 1N4738G

Overview

1N4738G from Taiwan Semiconductor is a 1 W, 8.2 V ±5% Zener diode in DO-41 glass package, designed for precision voltage regulation and reference applications with 4.5 Ω typical Zener impedance at 31 mA test current, used in DC/DC converters and low-voltage stabilizers.

For engineers reviewing the 1N4738G datasheet, 1N4738G pinout, 1N4738G application, or 1N4738G equivalent, key selection criteria include nominal Zener voltage (8.2 V), power rating (1 W), tolerance (±5%), thermal resistance (R_θJA = 100 °C/W), and DO-41 mechanical compatibility with through-hole PCB assembly.

Technical Context

The 1N4738G operates as a single-die, silicon planar Zener diode with hermetically sealed glass encapsulation, optimized for stable reverse-breakdown behavior under DC bias. Its 8.2 V nominal Zener voltage is specified at I_ZT = 31 mA, with regulated impedance (Z_ZT) of 4.5 Ω and knee impedance (Z_ZK) of 700 Ω at I_ZK = 0.5 mA.

Junction temperature range spans −65 °C to +200 °C, enabling operation in industrial environments. Thermal performance is defined by R_θJL = 53.5 °C/W and R_θJA = 100 °C/W, supporting reliable power dissipation up to 1 W at ambient temperatures ≤ 100 °C without forced cooling.

Key Specifications

Pinout & Package

Package: DO-41 glass axial-leaded package with cathode band marking; pure tin-plated leads compliant with J-STD-002 solderability; weight ≈ 242 mg.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4738G, the 1N4738A offers identical performance and drop-in compatibility, while BZX55C8V2 trades power capability for smaller footprint-making 1N4738G optimal for thermally demanding 1 W reference applications.

Availability

1N4738G is available at Aetrix Electronics and suitable for low-voltage stabilizers, on-board DC/DC converters, lighting applications, and adapter circuits requiring stable component supply with full traceability and RoHS compliance.

Supply support for 1N4738G 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, analog ICs, and protection components since 1979.

The 1N4738G belongs to TSC's 1N47xxG Zener diode family, engineered for high-reliability voltage reference and stabilization in industrial, computing, and consumer power systems.

FAQ

What is the nominal Zener voltage and tolerance of the 1N4738G?

The 1N4738G has a nominal Zener voltage of 8.2 V with a standard tolerance of ±5%, meaning its actual breakdown voltage falls between 7.79 V and 8.61 V at I_ZT = 31 mA. This tolerance is confirmed in Taiwan Semiconductor's G2301 datasheet and applies across the full operating temperature range.

What is the maximum power dissipation rating for the 1N4738G?

The 1N4738G is rated for 1 W maximum continuous power dissipation at 25 °C ambient temperature. Derating is required above 25 °C at 10 mW/°C based on its R_θJA = 100 °C/W, limiting usable power to 0.75 W at 100 °C ambient. This rating assumes free-air convection and DO-41 mounting per JEDEC standards.

Is the 1N4738G compatible with lead-free reflow soldering processes?

Yes, the 1N4738G features pure tin-plated leads compliant with J-STD-002 for solderability, and its glass DO-41 package withstands peak reflow temperatures up to 260 °C for 10 seconds. Taiwan Semiconductor confirms full compatibility with lead-free wave and reflow processes per IPC-J-STD-020D.

What is the Zener impedance of the 1N4738G and why does it matter?

The 1N4738G has a typical Zener impedance (Z_ZT) of 4.5 Ω at I_ZT = 31 mA. This low value ensures minimal output voltage variation under changing load currents-critical for precision references in feedback networks. Higher impedance would cause greater regulation error and ripple sensitivity.

How is polarity indicated on the 1N4738G package?

Polarity on the 1N4738G is indicated by a visible cathode band near one end of the DO-41 glass body. The banded end is the cathode, which must be connected to the higher-potential node in reverse-bias Zener operation. This marking aligns with JEDEC DO-41 standard and is verified in Taiwan Semiconductor's package outline drawing HQ2SD07-DO41-059 REV A.