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

onsemi 1N5991B_T50R

Name: 1N5991B_T50R
Brand: onsemi
SKU: 1N5991B_T50R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N5991B_T50R

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: DO-204AH, DO-35, Axial

Datasheet:: 1N5991B_T50R.pdf

Description:: DIODE ZENER 4.3V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:5,560

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Product details

Overview

1N5991B_T50R from Fairchild Semiconductor is a 4.3 V ±5% Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C with 4.0 mW/°C derating, 5 mA test current, and 88 Ω dynamic impedance at IZ - used for precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N5991B_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, leakage current (≤5 mA at VR = 1 V), maximum zener current (116 mA), and DO-35 mechanical compatibility in space-constrained PCB layouts.

Technical Context

This device operates as a two-terminal voltage-regulating element with sharp reverse-breakdown knee and stable zener voltage across its specified operating temperature range of –65°C to +200°C. Its 88 Ω zener impedance at 5 mA ensures minimal output voltage variation under load changes.

The 1N5991B_T50R exhibits 5 mA nominal test current and 116 mA maximum zener current (IZM), enabling reliable clamping in transient suppression and reference applications where thermal management is constrained by lead-length-dependent power derating.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	4.3 V nominal, min 4.085 V / max 4.515 V at 5 mA - defines precise clamping threshold for voltage regulation
Power Dissipation (P_D)	500 mW @ TL ≤ 75°C - sets maximum continuous power handling before thermal derating begins
Derating Factor	4.0 mW/°C above 75°C - determines safe power reduction per degree rise in lead temperature
Zener Impedance (Z_Z)	88 Ω @ I_Z = 5 mA - indicates small-signal AC resistance affecting regulation stability under varying load
Leakage Current (I_R)	≤5 mA @ V_R = 1 V - quantifies reverse-bias conduction below breakdown, critical for low-power standby circuits
Max Zener Current (I_ZM)	116 mA - establishes peak surge-handling capability without permanent degradation
Operating Temp Range	–65°C to +200°C - supports deployment in automotive under-hood, industrial, and aerospace environments

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; two-terminal device requiring no external biasing - anode and cathode terminals defined solely by physical orientation and marking.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to lower-potential node during forward bias; forms reference ground return path in shunt regulator configurations
Cathode	Zener breakdown terminal	Marked with color band; connected to higher-potential node to enable reverse-bias regulation at 4.3 V

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Ensures predictable clamping accuracy across production lots without post-manufacture trimming
DO-35 glass package	Provides hermetic sealing and high-temperature reliability up to +200°C junction operation
Low leakage current (≤5 mA @ 1 V)	Minimizes quiescent power loss in battery-powered or energy-harvesting systems
Stable 5 mA test current	Enables repeatable measurement and circuit design using standardized characterization conditions
Lead-length-dependent thermal rating	Supports flexible layout integration with defined derating rules for 3/8″ lead length

Applications

Power Supply Reference	Overvoltage Clamp
Use Scenario: Low-cost linear regulator feedback network in 5 V rail generation for microcontroller peripherals. IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 4.3 V setpoint to error amplifier input. Use Value: Maintains ±1% output regulation despite input ripple and load transients due to 88 Ω dynamic impedance.	Use Scenario: Protection circuit on ADC input line exposed to ESD events in portable instrumentation. IC Role / Device Role / Timing Role: Transient voltage suppressor clamping induced surges to ≤4.52 V peak. Use Value: Limits voltage excursion within ADC's absolute maximum rating (5 V) while drawing <5 mA leakage at 1 V bias.
Temperature-Stable Biasing	Calibration Voltage Source
Use Scenario: Bias network for op-amp input stage in automotive cabin temperature sensor interface. IC Role / Device Role / Timing Role: Precision DC reference establishing common-mode voltage across wide ambient range. Use Value: Delivers <±10 mV drift from –40°C to +125°C due to matched TC characteristics in DO-35 construction.	Use Scenario: Factory-trimmed reference in handheld multimeter front-end calibration circuitry. IC Role / Device Role / Timing Role: Stable 4.3 V benchmark against which DMM ADC gain is adjusted. Use Value: Enables 0.5% full-scale accuracy retention over 2-year calibration interval via tight ±5% initial tolerance.

Power Supply Reference

Overvoltage Clamp

Use Scenario: Low-cost linear regulator feedback network in 5 V rail generation for microcontroller peripherals.

IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 4.3 V setpoint to error amplifier input.

Use Value: Maintains ±1% output regulation despite input ripple and load transients due to 88 Ω dynamic impedance.

Use Scenario: Protection circuit on ADC input line exposed to ESD events in portable instrumentation.

IC Role / Device Role / Timing Role: Transient voltage suppressor clamping induced surges to ≤4.52 V peak.

Use Value: Limits voltage excursion within ADC's absolute maximum rating (5 V) while drawing <5 mA leakage at 1 V bias.

Temperature-Stable Biasing

Calibration Voltage Source

Use Scenario: Bias network for op-amp input stage in automotive cabin temperature sensor interface.

IC Role / Device Role / Timing Role: Precision DC reference establishing common-mode voltage across wide ambient range.

Use Value: Delivers <±10 mV drift from –40°C to +125°C due to matched TC characteristics in DO-35 construction.

Use Scenario: Factory-trimmed reference in handheld multimeter front-end calibration circuitry.

IC Role / Device Role / Timing Role: Stable 4.3 V benchmark against which DMM ADC gain is adjusted.

Use Value: Enables 0.5% full-scale accuracy retention over 2-year calibration interval via tight ±5% initial tolerance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4733A	5.1 V nominal, 1 W rating, DO-41 package, 17 Ω Z_Z @ 49 mA	Higher power and lower impedance but incompatible voltage level and larger footprint	Select when 5.1 V reference is required and board space allows DO-41 mounting
BZX55-C4V3	4.3 V nominal, ±5% tolerance, DO-35, 500 mW, 90 Ω Z_Z @ 5 mA	Nearly identical electrical specs but different manufacturer marking and traceability chain	Preferred for designs requiring Vishay-sourced components or dual-sourcing flexibility

Compared with 1N4733A and BZX55-C4V3, the 1N5991B_T50R offers tighter thermal stability over –65°C to +200°C and legacy Fairchild supply chain continuity, making it optimal for long-lifecycle industrial control modules where DO-35 form factor and exact 4.3 V regulation are mandatory.

Availability

1N5991B_T50R is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, and precision biasing applications requiring stable component supply across automotive, industrial sensing, and test equipment programs.

Supply support for 1N5991B_T50R 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016; known for robust, high-reliability components.

The 1N5991B_T50R belongs to Fairchild's legacy 1N59xxB Zener diode family, engineered for general-purpose voltage regulation and transient suppression in cost-sensitive, thermally demanding applications.

FAQ

What is the zener voltage tolerance for 1N5991B_T50R?

The 1N5991B_T50R has a ±5% zener voltage tolerance, meaning its breakdown voltage ranges from 4.085 V to 4.515 V at 5 mA test current and 25°C ambient. This tolerance is guaranteed across production lots and enables predictable performance in shunt regulator and reference designs without additional trimming circuitry.

Does 1N5991B_T50R support high-temperature operation?

Yes, the 1N5991B_T50R is rated for operation from –65°C to +200°C, with storage and junction temperatures spanning that full range. Its DO-35 glass package and silicon die construction allow sustained functionality in under-hood automotive, downhole, and industrial furnace monitoring applications where thermal resilience is critical.

What is the maximum zener current (I_ZM) for 1N5991B_T50R?

The maximum zener current for 1N5991B_T50R is 116 mA at 25°C, calculated based on its 4.3 V nominal zener voltage and 500 mW power rating. This value decreases linearly above 75°C lead temperature per the 4.0 mW/°C derating curve, ensuring safe operation under transient overload conditions.

How does the 1N5991B_T50R compare to 1N4733A in terms of package and voltage?

The 1N5991B_T50R uses a DO-35 glass package and delivers 4.3 V regulation, whereas the 1N4733A uses a larger DO-41 package and regulates at 5.1 V. Their differing voltages and footprints prevent direct substitution; the 1N5991B_T50R is selected specifically where 4.3 V reference and compact axial form factor are required.

Is forward voltage specified for 1N5991B_T50R?

Yes - the 1N5991B_T50R has a maximum forward voltage (V_F) of 1.2 V at 200 mA forward current, consistent with standard silicon diode behavior. This parameter is relevant for polarity-check circuits or applications where the device may experience brief forward conduction during power-up sequencing or fault conditions.

1N5991B_T50R Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: DO-204AH, DO-35, Axial

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 4.3 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 88 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 1 V

Voltage - Forward (Vf) (Max) @ If:: 1.2 V @ 200 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

1N5991B_T50R FAQ

1.How can I place an order for 1N5991B_T50R through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N5991B_T50R 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 1N5991B_T50R reliable?

The price and inventory of 1N5991B_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N5991B_T50R is usually 5 days.

3.What payment methods are accepted for 1N5991B_T50R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N5991B_T50R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N5991B_T50R?

1N5991B_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N5991B_T50R 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 1N5991B_T50R?

For technical support, including 1N5991B_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N5991B_T50R requirements.

6.How does Aetrix verify that 1N5991B_T50R is sourced from the original manufacturer or authorized distributors?

All 1N5991B_T50R 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 1N5991B_T50R meets industry standards.

7.What is the process for return or replacement of 1N5991B_T50R?

All 1N5991B_T50R units undergo pre-shipment inspection (PSI). If there is an issue with 1N5991B_T50R, 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 1N5991B_T50R part is unused and in its original packaging.

Return procedure for 1N5991B_T50R:

1.Submit a request within 90 days.

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

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