onsemi 1N4739A-T50A

Overview

1N4739A-T50A from ON Semiconductor is a 9.1 V, 1 W Zener diode in DO-41 glass package, rated for ±5% tolerance, 5 mA test current, and 28 Ω dynamic impedance at I_Z, used for precision voltage regulation and overvoltage protection in DC power supplies and reference circuits.

For engineers reviewing the 1N4739A-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy, thermal derating (6.67 mW/°C above 50°C), leakage current (≤0.5 µA at 7.3 V), peak reverse surge capability (500 mA), and DO-41 mechanical compatibility with through-hole PCB layouts.

Technical Context

The 1N4739A-T50A operates as a silicon planar Zener diode with sharp reverse breakdown at 9.1 V nominal, designed for stable voltage clamping under regulated DC bias. Its 28 Ω Zener impedance at 5 mA ensures low output variation across load changes, while the 0.5 µA max leakage at 7.3 V supports low-power standby operation.

Thermal design relies on lead temperature control: full 1.0 W power dissipation is only valid at T_L ≤ 50°C with 3/8″ lead length; derating begins immediately above that threshold. The -65°C to +200°C operating range enables use in industrial and automotive under-hood environments where ambient extremes are expected.

Key Specifications

Pinout & Package

DO-41 glass axial package with cathode band marking; leads are unmarked anode/cathode terminals requiring orientation verification via color band during placement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4739A-T50A, 1N4739A-TP offers identical performance in automated manufacturing, while BZX55C9V1 trades power capacity and impedance for smaller size-making the original optimal for robust 1 W regulation where DO-41 fit is acceptable.

Availability

1N4739A-T50A is available at Aetrix Electronics and suitable for DC power supply regulation, overvoltage protection circuits, and precision reference voltage sources requiring stable component supply with traceable lot history and full compliance documentation.

Supply support for 1N4739A-T50A 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

ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensors, and discrete devices, with emphasis on energy efficiency and reliability.

The 1N47xxA series was engineered for general-purpose voltage regulation in cost-sensitive industrial and consumer systems, prioritizing tight tolerance, proven DO-41 ruggedness, and broad thermal resilience.

FAQ

What is the Zener voltage tolerance of the 1N4739A-T50A?

The 1N4739A-T50A has a Zener voltage tolerance of ±5% at 5 mA test current, meaning its actual breakdown voltage falls between 8.645 V and 9.555 V under standard conditions. This tolerance is guaranteed per ON Semiconductor's 1N4728A–1N4758A datasheet Rev. 8. The 1N4739A-T50A achieves this specification using tightly controlled silicon doping and process validation, making it suitable for applications requiring predictable clamping without external trimming.

Can the 1N4739A-T50A be used in surface-mount designs?

No-the 1N4739A-T50A uses a DO-41 axial glass package intended for through-hole mounting only. It lacks solder pads or gull-wing leads required for reflow soldering. For SMT equivalents, consider ON Semiconductor's NSZ9V1AXV6T1G (SOD-323) or similar, but note differences in power rating and thermal behavior. The 1N4739A-T50A must be manually or wave-soldered into plated-through holes.

What is the maximum allowable junction temperature for the 1N4739A-T50A?

While the 1N4739A-T50A specifies an operating junction temperature range of -65°C to +200°C, its safe continuous operation depends on thermal management. At ambient temperatures above 50°C, power must be derated at 6.67 mW/°C. Exceeding the thermal limit risks irreversible Zener parameter shift or catastrophic failure. The 1N4739A-T50A's glass DO-41 case provides limited heat spreading, so PCB copper area and lead length are critical for thermal performance.

How does the 1N4739A-T50A compare to the 1N4738A and 1N4740A in terms of voltage rating?

The 1N4739A-T50A is the middle variant in a 0.9 V step sequence: 1N4738A = 8.2 V, 1N4739A-T50A = 9.1 V, and 1N4740A = 10 V, all with ±5% tolerance and identical 1 W rating. Their Zener impedances differ-28 Ω for 1N4739A-T50A versus 31 Ω (1N4738A) and 25 Ω (1N4740A)-reflecting process optimization per voltage grade. Select 1N4739A-T50A specifically when 9.1 V regulation is required; substituting adjacent parts introduces systematic offset errors.

Is the 1N4739A-T50A RoHS compliant and halogen-free?

Yes-the 1N4739A-T50A meets RoHS Directive 2011/65/EU and is halogen-free per ON Semiconductor's material declarations. Its DO-41 glass package contains no lead in solderable terminations, and the internal die construction avoids restricted substances. Compliance documentation-including Certificates of Conformance and IMDS reports-is available upon request for the 1N4739A-T50A, supporting environmental compliance in medical, industrial, and consumer end products.