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

onsemi 1N974B_T50R

Name: 1N974B_T50R
Brand: onsemi
SKU: 1N974B_T50R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N974B_T50R

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: 1N974B_T50R.pdf

Description:: DIODE ZENER 36V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:8,459

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Product details

Overview

1N974B_T50R from Fairchild Semiconductor is a 36 V, ±5% tolerance, 500 mW glass-encapsulated Zener diode in DO-35 package, designed for precision voltage regulation and reference applications in power supply feedback loops, overvoltage protection circuits, and analog signal conditioning. It exhibits 3.4 Ω typical zener impedance at 5 mA and operates across –65°C to +200°C.

For engineers reviewing the 1N974B_T50R datasheet, pinout, applications, or equivalent options, key selection criteria include its 36 V nominal zener voltage, low dynamic impedance, tight 5% tolerance, DO-35 mechanical compatibility, and thermal stability up to +200°C junction temperature.

Technical Context

The 1N974B_T50R functions as a two-terminal voltage reference device with reverse-biased operation. Its zener breakdown is engineered for stable regulation at I_Z = 5 mA, where V_Z = 34.2 V (min) to 37.8 V (max), and dynamic impedance is specified at 3.4 Ω (typ) under AC test conditions (I_Z(ac) = 0.1 × I_Z(dc), 60 Hz).

It adheres to JEDEC DO-35 mechanical standards with axial leads and cathode band marking. Power dissipation is rated at 500 mW up to 75°C ambient, derating linearly at 4.0 mW/°C above that, enabling reliable operation in industrial and automotive environments.

Key Specifications

Parameter	Value and Actual Design Meaning
V_Z Nominal	36 V - precise DC reference voltage at 5 mA test current
V_Z Tolerance	±5% - ensures voltage accuracy within 34.2–37.8 V at 25°C
Z_Z @ I_Z = 5 mA	3.4 Ω (typ) - low dynamic impedance enables stable regulation under load variation
P_D @ T_L ≤ 75°C	500 mW - maximum continuous power in standard lead configuration (3/8″)
Operating Temp Range	–65°C to +200°C - supports high-reliability deployment in extreme environments
I_R @ V_R = 29.7 V	0.25 μA - ultra-low leakage preserves regulation integrity in high-impedance bias networks
I_ZM Max	70 mA - peak current limit derived from V_Z and derated power envelope

Pinout & Package

DO-35 glass axial package with cathode indicated by a color band on the body. Leads are tinned copper-clad steel, suitable for wave or hand soldering. Mechanical dimensions conform to JEDEC TO-204AA standard.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Reference ground node	Connected to circuit common when used in reverse-bias regulation mode
Cathode	Zener breakdown terminal / Voltage reference output	Marked with color band; supplies regulated voltage relative to anode

Key Features

Feature	Design Value
Stable Zener voltage	36 V ±5% at 5 mA - enables accurate feedback in switching regulator error amplifiers
Low dynamic impedance	3.4 Ω typical - minimizes output voltage deviation during transient load changes
High-temperature operation	Junction range –65°C to +200°C - qualified for under-hood automotive and downhole industrial use
Hermetic glass seal	DO-35 package - provides moisture resistance and long-term parameter stability vs. plastic packages

Applications

Power Supply Feedback	Overvoltage Clamp
Use Scenario: Regulating output voltage in isolated flyback or forward converters via optocoupler-coupled feedback loop. IC Role / Device Role / Timing Role: Zener reference providing stable 36 V threshold to TL431 shunt regulator or discrete error amplifier. Use Value: Tight 5% tolerance and low ZZ ensure ±1% output regulation accuracy across line/load/temperature.	Use Scenario: Protecting microcontroller I/O pins or ADC inputs from ESD-induced transients exceeding 30 V. IC Role / Device Role / Timing Role: Shunt clamping element diverting surge current when input exceeds 36 V. Use Value: Sub-μA leakage at 29.7 V prevents signal degradation in high-impedance sensor interfaces.
Reference Voltage Source	Current Source Bias
Use Scenario: Generating a stable 36 V reference for DAC output scaling or precision comparator thresholds. IC Role / Device Role / Timing Role: Two-terminal passive voltage reference replacing active IC references where cost and simplicity are critical. Use Value: DO-35 footprint allows direct replacement of legacy references without PCB redesign.	Use Scenario: Setting constant current in LED driver or op-amp bias network using resistor-Zener combination. IC Role / Device Role / Timing Role: Voltage-setting element establishing fixed drop across series bias resistor. Use Value: 3.4 Ω ZZ ensures current stability within ±0.5% over 10–100% load range.

Power Supply Feedback

Overvoltage Clamp

Use Scenario: Regulating output voltage in isolated flyback or forward converters via optocoupler-coupled feedback loop.

IC Role / Device Role / Timing Role: Zener reference providing stable 36 V threshold to TL431 shunt regulator or discrete error amplifier.

Use Value: Tight 5% tolerance and low ZZ ensure ±1% output regulation accuracy across line/load/temperature.

Use Scenario: Protecting microcontroller I/O pins or ADC inputs from ESD-induced transients exceeding 30 V.

IC Role / Device Role / Timing Role: Shunt clamping element diverting surge current when input exceeds 36 V.

Use Value: Sub-μA leakage at 29.7 V prevents signal degradation in high-impedance sensor interfaces.

Reference Voltage Source

Current Source Bias

Use Scenario: Generating a stable 36 V reference for DAC output scaling or precision comparator thresholds.

IC Role / Device Role / Timing Role: Two-terminal passive voltage reference replacing active IC references where cost and simplicity are critical.

Use Value: DO-35 footprint allows direct replacement of legacy references without PCB redesign.

Use Scenario: Setting constant current in LED driver or op-amp bias network using resistor-Zener combination.

IC Role / Device Role / Timing Role: Voltage-setting element establishing fixed drop across series bias resistor.

Use Value: 3.4 Ω ZZ ensures current stability within ±0.5% over 10–100% load range.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4738A	33 V nominal, same DO-35 package, 5% tolerance, 7 Ω Z_Z @ 5 mA	Lower voltage rating; higher dynamic impedance reduces regulation fidelity	Select when 33 V reference suffices and tighter ZZ is not required
BZX55-C36	36 V nominal, DO-35, 5% tolerance, 500 mW, but 10 Ω Z_Z @ 5 mA	Higher dynamic impedance limits performance in fast-transient applications	Prefer for cost-sensitive designs where 36 V match is essential but low ZZ is secondary

Compared with 1N974B_T50R, the 1N4738A offers lower voltage and higher impedance, while BZX55-C36 matches voltage but sacrifices regulation stiffness-making 1N974B_T50R optimal where 36 V accuracy and low-impedance stability are design-critical.

Availability

1N974B_T50R is available at Aetrix Electronics and suitable for power supply feedback, overvoltage protection, and precision reference applications requiring stable component supply and long-lifecycle support.

Supply support for 1N974B_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 components before its acquisition by ON Semiconductor in 2016.

The 1N974B_T50R belongs to the legacy 1N957B–1N979B Zener diode family, engineered for high-stability voltage reference and regulation in industrial, automotive, and telecom infrastructure systems.

FAQ

What is the nominal zener voltage of the 1N974B_T50R?

The 1N974B_T50R has a nominal zener voltage of 36 V, with a guaranteed range of 34.2 V (min) to 37.8 V (max) at 5 mA test current and 25°C ambient. This value is defined per Fairchild's Rev. F1 datasheet and reflects the device's primary function as a precision voltage reference in regulation circuits.

What package type does the 1N974B_T50R use?

The 1N974B_T50R uses a DO-35 glass axial package with a cathode identification band. Its mechanical outline complies with JEDEC TO-204AA standards, and it features tinned copper-clad steel leads suitable for wave or hand soldering without special pre-treatment.

What is the maximum power dissipation for the 1N974B_T50R?

The 1N974B_T50R is rated for 500 mW power dissipation at lead temperature ≤ 75°C with 3/8″ lead length. Above 75°C, it derates linearly at 4.0 mW/°C, supporting thermal design up to +200°C junction temperature in properly heatsinked or low-power configurations.

How does the dynamic impedance of the 1N974B_T50R affect regulation performance?

The 1N974B_T50R exhibits 3.4 Ω typical dynamic impedance at 5 mA, measured with 60 Hz AC signal at 10% of DC bias. This low ZZ minimizes output voltage variation under changing load conditions, making the 1N974B_T50R especially effective in feedback paths where regulation stiffness directly impacts system accuracy.

Is the 1N974B_T50R suitable for high-temperature environments?

Yes-the 1N974B_T50R is rated for operation from –65°C to +200°C, verified per its Absolute Maximum Ratings table. Its glass-encapsulated DO-35 construction and silicon die process enable sustained performance in under-hood automotive, downhole oil/gas, and industrial control applications where extended thermal range is mandatory.

1N974B_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):: 36 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 70 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 27.4 V

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

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

1N974B_T50R FAQ

1.How can I place an order for 1N974B_T50R through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N974B_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 1N974B_T50R reliable?

The price and inventory of 1N974B_T50R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N974B_T50R is usually 5 days.

3.What payment methods are accepted for 1N974B_T50R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N974B_T50R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N974B_T50R?

1N974B_T50R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N974B_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 1N974B_T50R?

For technical support, including 1N974B_T50R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N974B_T50R requirements.

6.How does Aetrix verify that 1N974B_T50R is sourced from the original manufacturer or authorized distributors?

All 1N974B_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 1N974B_T50R meets industry standards.

7.What is the process for return or replacement of 1N974B_T50R?

All 1N974B_T50R units undergo pre-shipment inspection (PSI). If there is an issue with 1N974B_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 1N974B_T50R part is unused and in its original packaging.

Return procedure for 1N974B_T50R:

1.Submit a request within 90 days.

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

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