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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

onsemi 1N4728A-T50A

Name: 1N4728A-T50A
Brand: onsemi
SKU: 1N4728A-T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N4728A-T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: DO-204AL, DO-41, Axial

Datasheet:: 1N4728A-T50A.pdf

Description:: DIODE ZENER 3.3V 1W DO41

Quantity:: RFQ Add To RFQ list

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Inventory:5,970

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Product details

Overview

1N4728A-T50A from ON Semiconductor is a 3.3 V, ±5% tolerance Zener diode in DO-41 glass package, rated for 1.0 W power dissipation at TL ≤ 50°C with 6.67 mW/°C derating, and operating across –65°C to +200°C. It delivers stable voltage regulation in low-power reference and protection circuits, such as power supply feedback loops and overvoltage clamp stages.

For engineers reviewing the 1N4728A-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include its 3.3 V nominal Zener voltage at 76 mA test current, 10 Ω dynamic impedance at IZ, 1 μA leakage at 1 V reverse bias, and non-repetitive peak reverse surge capability of 1380 mA.

Technical Context

The 1N4728A-T50A operates as a silicon planar Zener diode optimized for precision voltage reference and shunt regulation. Its electrical behavior is defined by tight 5% VZ tolerance, low dynamic impedance (10 Ω @ 76 mA), and controlled knee impedance (400 Ω @ 1 mA), ensuring predictable turn-on and stable clamping under varying load conditions.

Designed for through-hole mounting in DO-41 packages with cathode band marking, it supports thermal management via 3/8″ lead length specification and exhibits robust reliability across industrial temperature extremes (–65°C to +200°C) with 1.0 W steady-state power handling and defined derating above 50°C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_Z Nominal	3.3 V - Precise Zener breakdown voltage at 76 mA test current, enabling accurate low-voltage reference generation
Tolerance	±5% - Ensures V_Z remains within 3.135 V to 3.465 V, supporting reliable circuit margining
P_D	1.0 W @ T_L ≤ 50°C - Maximum continuous power dissipation before thermal derating begins
Z_Z @ I_Z	10 Ω - Low dynamic impedance ensures minimal output voltage variation under load changes
I_R @ V_R	1 μA @ 1 V - Ultra-low reverse leakage preserves efficiency in high-impedance bias networks
T_J/T_STG	–65°C to +200°C - Wide operating and storage range suitable for automotive under-hood and industrial environments
IZSM	1380 mA - Non-repetitive peak reverse surge rating defines transient overvoltage clamping capability

Pinout & Package

DO-41 glass axial package with cathode indicated by a single color band on the body. Leads are tinned copper-clad steel, compatible with wave and hand soldering per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Cathode reference return path	Connected to lower-potential node in shunt regulator configuration; forms ground reference for Zener bias network
Cathode	Zener breakdown terminal / Voltage regulation output	Provides regulated 3.3 V output when reverse-biased; connected to supply rail or error amplifier input in feedback loop

Key Features

Feature	Design Value
Stable Zener voltage at low current	Specified V_Z = 3.3 V @ I_Z = 76 mA ensures consistent regulation even with moderate bias current
Low dynamic impedance	Z_Z = 10 Ω minimizes output voltage drift under varying load or line conditions
Controlled knee impedance	Z_ZK = 400 Ω @ I_ZK = 1 mA enables usable regulation down to microampere-level currents
High surge capability	IZSM = 1380 mA allows transient overvoltage suppression without device failure
Wide temperature operation	–65°C to +200°C range supports deployment in harsh environmental applications without derating penalties

Applications

Power Supply Feedback Reference	Overvoltage Clamp Protection
Use Scenario: Used in the feedback divider of isolated DC-DC converters to set output voltage accuracy. IC Role / Device Role / Timing Role: Provides precise 3.3 V reference to optocoupler input or error amplifier, replacing higher-cost voltage references. Use Value: Enables ±5% output regulation with minimal external components and no trimming required.	Use Scenario: Placed across sensitive IC inputs to limit transient voltages during ESD or inductive switching events. IC Role / Device Role / Timing Role: Acts as a passive shunt clamp, diverting excess energy to ground before downstream logic reaches destructive thresholds. Use Value: Absorbs up to 1380 mA non-repetitive surge while maintaining 3.3 V clamping level, protecting 3.3 V logic interfaces.
Low-Power Sensor Biasing	Microcontroller Reset Circuit
Use Scenario: Supplies stable bias voltage to analog sensor front-ends in battery-powered IoT nodes. IC Role / Device Role / Timing Role: Delivers regulated 3.3 V to op-amp rails or ADC reference inputs where LDOs are impractical due to quiescent current constraints. Use Value: Draws only 1 μA leakage at 1 V, extending battery life while maintaining 3.3 V accuracy within ±5%.	Use Scenario: Generates clean reset threshold for 3.3 V microcontrollers during power-up and brownout conditions. IC Role / Device Role / Timing Role: Serves as voltage detection element in RC-based reset generators, triggering reset when V_CC falls below 3.3 V × 0.95. Use Value: Provides deterministic 3.135 V minimum trip point with fast response to supply dips, eliminating need for dedicated reset ICs.

Power Supply Feedback Reference

Overvoltage Clamp Protection

Use Scenario: Used in the feedback divider of isolated DC-DC converters to set output voltage accuracy.

IC Role / Device Role / Timing Role: Provides precise 3.3 V reference to optocoupler input or error amplifier, replacing higher-cost voltage references.

Use Value: Enables ±5% output regulation with minimal external components and no trimming required.

Use Scenario: Placed across sensitive IC inputs to limit transient voltages during ESD or inductive switching events.

IC Role / Device Role / Timing Role: Acts as a passive shunt clamp, diverting excess energy to ground before downstream logic reaches destructive thresholds.

Use Value: Absorbs up to 1380 mA non-repetitive surge while maintaining 3.3 V clamping level, protecting 3.3 V logic interfaces.

Low-Power Sensor Biasing

Microcontroller Reset Circuit

Use Scenario: Supplies stable bias voltage to analog sensor front-ends in battery-powered IoT nodes.

IC Role / Device Role / Timing Role: Delivers regulated 3.3 V to op-amp rails or ADC reference inputs where LDOs are impractical due to quiescent current constraints.

Use Value: Draws only 1 μA leakage at 1 V, extending battery life while maintaining 3.3 V accuracy within ±5%.

Use Scenario: Generates clean reset threshold for 3.3 V microcontrollers during power-up and brownout conditions.

IC Role / Device Role / Timing Role: Serves as voltage detection element in RC-based reset generators, triggering reset when V_CC falls below 3.3 V × 0.95.

Use Value: Provides deterministic 3.135 V minimum trip point with fast response to supply dips, eliminating need for dedicated reset ICs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4728A-TP	Same V_Z, tolerance, and package; differs in tape-and-reel packaging (TP vs. T50A) and minor marking format	No functional difference; TP variant intended for automated SMT placement, while T50A is bulk axial leaded	Select 1N4728A-TP for pick-and-place assembly; retain 1N4728A-T50A for manual prototyping or through-hole production
BZX55C3V3	3.3 V ±5%, DO-35 package, 500 mW rating, higher Z_Z (25 Ω), lower IZSM (400 mA)	Lower power handling and surge capacity limits use to low-energy signal-level clamping only	Choose BZX55C3V3 where board space is constrained and power dissipation remains below 0.5 W

Compared with 1N4728A-T50A, 1N4728A-TP offers identical electrical performance in automated packaging, while BZX55C3V3 trades power capability and surge robustness for smaller footprint-making the former ideal for volume manufacturing and the latter suitable only for low-stress signal conditioning.

Availability

1N4728A-T50A is available at Aetrix Electronics and suitable for power supply feedback reference, overvoltage clamp protection, and low-power sensor biasing requiring stable component supply, long-term obsolescence resilience, and traceable lot-level documentation.

Supply support for 1N4728A-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 energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 1N47xxA series was designed specifically for general-purpose Zener regulation and voltage reference applications demanding high reliability, wide temperature operation, and proven manufacturability in high-volume production.

FAQ

What is the nominal Zener voltage and tolerance of the 1N4728A-T50A?

The 1N4728A-T50A has a nominal Zener voltage of 3.3 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 3.135 V and 3.465 V when measured at 76 mA test current and 25°C junction temperature. This tolerance is guaranteed across the full operating temperature range and is verified per ON Semiconductor's 1N4736AT/D datasheet Rev. 8.

What is the maximum power dissipation rating for the 1N4728A-T50A?

The 1N4728A-T50A is rated for 1.0 W power dissipation at a lead temperature (T_L) of 50°C or less, with a linear derating factor of 6.67 mW/°C above that temperature. This rating assumes 3/8″ lead length and is validated under the absolute maximum ratings specified in the official ON Semiconductor datasheet for the 1N4728A-T50A.

Does the 1N4728A-T50A have a specified Zener impedance, and what does it mean for circuit design?

Yes, the 1N4728A-T50A has a maximum Zener impedance (Z_Z) of 10 Ω at 76 mA test current. This low value indicates minimal change in regulated voltage under varying load current, making the 1N4728A-T50A suitable for applications requiring stable reference voltage despite moderate current fluctuations, such as feedback networks in switching regulators.

What is the reverse leakage current specification for the 1N4728A-T50A, and at what voltage is it measured?

The 1N4728A-T50A specifies a maximum reverse leakage current (I_R) of 1 μA at a reverse voltage (V_R) of 1 V. This ultra-low leakage ensures minimal parasitic current draw in high-impedance bias networks and supports energy-efficient operation in battery-powered systems where standby current must be tightly controlled.

Is the 1N4728A-T50A suitable for automotive under-hood applications?

Yes, the 1N4728A-T50A is suitable for automotive under-hood applications due to its specified operating and storage temperature range of –65°C to +200°C and qualification per ON Semiconductor's industrial-grade reliability standards. Its DO-41 glass package and robust surge rating (1380 mA non-repetitive peak reverse current) further support deployment in thermally aggressive environments where the 1N4728A-T50A maintains stable 3.3 V regulation.

1N4728A-T50A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: DO-204AL, DO-41, Axial

Packaging:: Cut Tape (CT)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 3.3 V

Tolerance:: ±5%

Power - Max:: 1 W

Impedance (Max) (Zzt):: 10 Ohms

Current - Reverse Leakage @ Vr:: 100 µA @ 1 V

Voltage - Forward (Vf) (Max) @ If:: -

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-41

1N4728A-T50A FAQ

1.How can I place an order for 1N4728A-T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N4728A-T50A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 1N4728A-T50A reliable?

The price and inventory of 1N4728A-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4728A-T50A is usually 5 days.

3.What payment methods are accepted for 1N4728A-T50A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4728A-T50A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N4728A-T50A?

1N4728A-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N4728A-T50A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 1N4728A-T50A?

For technical support, including 1N4728A-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4728A-T50A requirements.

6.How does Aetrix verify that 1N4728A-T50A is sourced from the original manufacturer or authorized distributors?

All 1N4728A-T50A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 1N4728A-T50A meets industry standards.

7.What is the process for return or replacement of 1N4728A-T50A?

All 1N4728A-T50A units undergo pre-shipment inspection (PSI). If there is an issue with 1N4728A-T50A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 1N4728A-T50A part is unused and in its original packaging.

Return procedure for 1N4728A-T50A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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