Taiwan Semiconductor Corporation 1N4737G

Overview

1N4737G from Taiwan Semiconductor is a 1 W, 7.5 V ±5% Zener diode in DO-41 glass package, designed for precision voltage regulation and reference applications with 34 mA test current, 4 Ω dynamic impedance at IZT, and 0.5 mA knee current. It operates across -65°C to +200°C junction temperature range and serves in low-voltage DC/DC converters and LED lighting bias circuits.

For engineers reviewing the 1N4737G datasheet, 1N4737G pinout, 1N4737G application, or 1N4737G equivalent, key selection factors include its tight ±5% VZ tolerance, hermetically sealed glass construction, DO-41 mechanical compatibility, and verified thermal resistance (RθJL = 53.5°C/W) for stable operation under continuous power dissipation.

Technical Context

The 1N4737G functions as a single-die, silicon-based Zener diode optimized for reverse-biased breakdown regulation at 7.5 V nominal. Its design supports stable DC voltage reference generation with low dynamic impedance (4 Ω at 34 mA) and controlled leakage (<10 µA at 5 V), enabling predictable clamping in power supply feedback paths and analog reference nodes.

It features hermetic glass encapsulation per DO-41 outline, pure tin-plated leads compliant with J-STD-002 solderability, and polarity indicated by cathode band. Thermal performance is defined by RθJA = 100°C/W and RθJL = 53.5°C/W, supporting reliable 1 W operation without forced cooling in standard PCB layouts.

Key Specifications

Pinout & Package

Package: DO-41 glass axial package with cathode band marking; 2.80 mm diameter body, 5.20 mm lead spacing, 242 mg mass; RoHS-compliant, hermetically sealed, pure tin-plated leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4737A and BZX55C7V5, the 1N4737G offers superior thermal performance (RθJL = 53.5°C/W) and full 1 W capability in the industry-standard DO-41 footprint-making it optimal for industrial power supplies and lighting drivers requiring robust, field-proven reliability.

Availability

1N4737G is available at Aetrix Electronics and suitable for LED lighting bias reference, DC/DC converter feedback, and low-voltage stabilizer applications requiring stable component supply, long-lifecycle support, and RoHS-compliant through-hole Zener diodes.

Supply support for 1N4737G 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, rectifiers, and Zener diodes for industrial, computing, and consumer applications.

The 1N47xxG series was developed to deliver high-reliability, glass-encapsulated Zener diodes with tight tolerances and extended temperature capability for mission-critical voltage reference and protection functions.

FAQ

What is the Zener voltage and tolerance of the 1N4737G?

The 1N4737G has a nominal Zener voltage of 7.5 V with a standard tolerance of ±5% at 34 mA test current (IZT). This means its actual breakdown voltage falls between 7.125 V and 7.875 V under specified conditions, ensuring predictable regulation in feedback and reference circuits where tight voltage control is required. The 1N4737G maintains this tolerance across its qualified operating temperature range.

What is the maximum power dissipation rating for the 1N4737G?

The 1N4737G is rated for 1 W maximum continuous power dissipation at 25°C ambient temperature. Derating is required above 25°C per its thermal resistance specs: RθJA = 100°C/W and RθJL = 53.5°C/W. At 70°C ambient, usable power drops to approximately 0.55 W. The 1N4737G must be mounted with adequate copper area or heatsinking to avoid exceeding TJ = 200°C.

Does the 1N4737G have a cathode marking, and how is polarity identified?

Yes, the 1N4737G uses a visible cathode band painted on the glass body to indicate polarity-this band identifies the cathode terminal, which must be connected to the higher-potential side of the circuit when used in reverse-bias Zener regulation mode. The anode is the unmarked lead. This marking complies with JEDEC DO-41 standards and is clearly visible during manual or automated assembly of the 1N4737G.

What is the Zener impedance (ZZT) of the 1N4737G, and why does it matter?

The 1N4737G exhibits a Zener impedance (ZZT) of 4 Ω measured at its 34 mA test current (IZT). This low dynamic impedance means the device maintains stable output voltage under varying load conditions-critical for precision references in analog circuits and feedback loops. A lower ZZT directly translates to reduced output voltage ripple and improved regulation accuracy, making the 1N4737G suitable for demanding applications like LED driver biasing.

Is the 1N4737G RoHS compliant and lead-free?

Yes, the 1N4737G is RoHS compliant and features pure tin-plated leads that meet J-STD-002 solderability requirements. Its green compound encapsulation and halogen-free materials align with EU RoHS Directive 2011/65/EU. No lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE substances exceed allowable thresholds. This compliance is confirmed in Taiwan Semiconductor's official documentation for the 1N4737G.