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

onsemi BZX55C43_T50A

Name: BZX55C43_T50A
Brand: onsemi
SKU: BZX55C43_T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX55C43_T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: BZX55C43_T50A.pdf

Description:: DIODE ZENER 43V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:3,136

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Product details

Overview

BZX55C43_T50A from Fairchild Semiconductor is a 43 V ±5% tolerance silicon Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C, with 90 Ω dynamic impedance at 2.5 mA test current and 0.1 μA reverse leakage at 32 V. It provides precise voltage regulation in low-power reference and protection circuits.

For engineers reviewing the BZX55C43_T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, thermal derating behavior, dynamic impedance at specified test current, reverse leakage at rated VR, and DO-35 mechanical compatibility in space-constrained analog designs.

Technical Context

The BZX55C43_T50A operates as a two-terminal voltage reference device relying on controlled reverse-biased avalanche breakdown. Its 43 V nominal zener voltage is specified at 2.5 mA test current with ±5% tolerance, and it maintains stable regulation across -65°C to +200°C operating temperature range.

Thermal performance is defined by 4.0 mW/°C derating above 75°C lead temperature, and its 90 Ω dynamic impedance (ZZ) directly impacts output voltage stability under varying load conditions. Reverse leakage remains ≤0.1 μA at 32 V, supporting low-power standby functionality.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	43 V nominal, ±5% tolerance - ensures regulated output within 40.85–45.15 V at 2.5 mA
Power Dissipation (P_D)	500 mW @ T_L ≤ 75°C - defines maximum continuous steady-state power handling
Dynamic Impedance (Z_Z)	90 Ω @ I_Z = 2.5 mA - determines voltage deviation under small-signal current variation
Reverse Leakage (I_R)	≤0.1 μA @ V_R = 32 V - enables ultra-low quiescent current in bias/reference paths
Test Current (I_Z)	2.5 mA - standardized condition for V_Z measurement and datasheet compliance
Operating Temp Range	-65°C to +200°C - supports deployment in automotive under-hood and industrial environments
Forward Voltage (V_F)	≤1.3 V @ I_F = 100 mA - confirms standard silicon PN junction conduction behavior

Pinout & Package

DO-35 glass axial package with cathode indicated by color band; two-terminal device with no internal connections beyond anode and cathode leads.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Zener reference return	Connected to circuit ground or lower potential node in shunt regulator configuration
Cathode	Zener breakdown terminal / regulated output node	Connected to input voltage source; clamps voltage to 43 V when reverse biased above breakdown

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables predictable regulation without post-production trimming in cost-sensitive applications
DO-35 glass package	Provides hermetic sealing and thermal stability for long-term parameter consistency
90 Ω dynamic impedance	Minimizes output voltage shift under ±1 mA load transients in precision references
0.1 μA max reverse leakage at 32 V	Reduces standby power loss in battery-backed or energy-harvesting systems
200°C max junction temperature	Supports operation in high-ambient environments such as motor control enclosures

Applications

Voltage Reference for ADC Biasing	Overvoltage Clamp in Sensor Interface
Use Scenario: Providing stable 43 V reference for 16-bit SAR ADC driver stage in industrial data acquisition modules. IC Role / Device Role / Timing Role: Shunt voltage reference establishing precise common-mode level for differential input amplifiers. Use Value: Maintains <±0.5 LSB error contribution over temperature due to tight 43 V ±5% tolerance and low ZZ.	Use Scenario: Protecting 3.3 V microcontroller GPIO pins from transient surges on 48 V CAN bus lines via resistive divider + clamp network. IC Role / Device Role / Timing Role: Fast-acting overvoltage clamp limiting voltage excursion to 43 V before damage threshold. Use Value: Prevents latch-up with 0.1 μA leakage ensuring minimal loading on divider network during normal operation.
Power Supply Feedback Divider	Field Transmitter Loop Calibration
Use Scenario: Setting feedback ratio in isolated 48 V DC-DC converter using optocoupler-coupled secondary-side regulation. IC Role / Device Role / Timing Role: Precision voltage reference defining upper threshold of resistor divider network. Use Value: Enables ±1% output regulation accuracy across line/load/temperature with stable 43 V reference point.	Use Scenario: Calibrating 4–20 mA field transmitter output stages where loop supply ranges from 12–48 V. IC Role / Device Role / Timing Role: Zener-based voltage limiter stabilizing internal reference against supply variation. Use Value: Ensures calibration integrity over full loop voltage range with 200°C max T_J rating surviving enclosure heating.

Voltage Reference for ADC Biasing

Overvoltage Clamp in Sensor Interface

Use Scenario: Providing stable 43 V reference for 16-bit SAR ADC driver stage in industrial data acquisition modules.

IC Role / Device Role / Timing Role: Shunt voltage reference establishing precise common-mode level for differential input amplifiers.

Use Value: Maintains <±0.5 LSB error contribution over temperature due to tight 43 V ±5% tolerance and low ZZ.

Use Scenario: Protecting 3.3 V microcontroller GPIO pins from transient surges on 48 V CAN bus lines via resistive divider + clamp network.

IC Role / Device Role / Timing Role: Fast-acting overvoltage clamp limiting voltage excursion to 43 V before damage threshold.

Use Value: Prevents latch-up with 0.1 μA leakage ensuring minimal loading on divider network during normal operation.

Power Supply Feedback Divider

Field Transmitter Loop Calibration

Use Scenario: Setting feedback ratio in isolated 48 V DC-DC converter using optocoupler-coupled secondary-side regulation.

IC Role / Device Role / Timing Role: Precision voltage reference defining upper threshold of resistor divider network.

Use Value: Enables ±1% output regulation accuracy across line/load/temperature with stable 43 V reference point.

Use Scenario: Calibrating 4–20 mA field transmitter output stages where loop supply ranges from 12–48 V.

IC Role / Device Role / Timing Role: Zener-based voltage limiter stabilizing internal reference against supply variation.

Use Value: Ensures calibration integrity over full loop voltage range with 200°C max T_J rating surviving enclosure heating.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4749A	43 V nominal, ±5%, 1 W power rating, DO-41 package	Higher power handling but larger footprint; requires PCB layout change	Select when >500 mW dissipation or higher surge robustness is required
BZX55C43-TR	Identical electrical specs, same DO-35 package, tape-and-reel packaging variant	No functional or mechanical difference; differs only in packaging format	Choose for automated SMT assembly requiring reel-fed feeders

Compared with 1N4749A and BZX55C43-TR, the BZX55C43_T50A offers identical voltage regulation performance in the compact DO-35 form factor, making it optimal for space-constrained through-hole designs where 500 mW dissipation suffices and tape-and-reel is not required.

Availability

BZX55C43_T50A is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, and power supply feedback applications requiring stable component supply, consistent parametric performance, and long-term obsolescence management.

Supply support for BZX55C43_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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, signal conditioning, and discrete components before its acquisition by ON Semiconductor in 2016.

The BZX55 series was developed as a general-purpose, cost-optimized Zener diode family targeting industrial instrumentation, power supply regulation, and circuit protection in through-hole designs.

FAQ

What is the nominal zener voltage and tolerance of the BZX55C43_T50A?

The BZX55C43_T50A has a nominal zener voltage of 43 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 40.85 V and 45.15 V when measured at 2.5 mA test current and 25°C ambient. This tolerance is guaranteed per the Fairchild BZX55C2V4–BZX55C56 datasheet Rev. D1, and applies specifically to the BZX55C43_T50A variant within the family.

What is the maximum power dissipation rating for the BZX55C43_T50A?

The BZX55C43_T50A is rated for 500 mW power dissipation at a lead temperature (T_L) of ≤75°C with 3/8" lead length. Above 75°C, it must be derated linearly at 4.0 mW/°C. This rating is defined under steady-state thermal equilibrium and is critical for calculating safe operating area in shunt regulator designs using the BZX55C43_T50A.

Does the BZX55C43_T50A have a specified dynamic impedance, and at what condition?

Yes, the BZX55C43_T50A has a typical dynamic impedance (Z_Z) of 90 Ω, measured at the specified test current of 2.5 mA and 25°C. This value reflects how tightly the device regulates voltage under small-signal AC variations and is essential for evaluating output stability in precision reference circuits using the BZX55C43_T50A.

What is the reverse leakage current specification for the BZX55C43_T50A?

The BZX55C43_T50A exhibits a maximum reverse leakage current (I_R) of 0.1 μA when subjected to 32 V reverse bias at 25°C. This ultra-low leakage supports energy-efficient operation in battery-powered or always-on monitoring circuits where standby current must be minimized - a verified parameter for the BZX55C43_T50A in the official Fairchild datasheet.

What package type does the BZX55C43_T50A use, and how is polarity marked?

The BZX55C43_T50A uses the DO-35 glass axial package with cathode identified by a distinct color band on the body. The anode and cathode leads extend axially from opposite ends, and the marking follows Fairchild's standard top-marking convention: "F" logo on first line, "5C" on second, and "43" on third line - confirming identity and polarity for the BZX55C43_T50A.

BZX55C43_T50A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 43 V

Tolerance:: ±7%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 90 Ohms

Current - Reverse Leakage @ Vr:: 100 nA @ 32 V

Voltage - Forward (Vf) (Max) @ If:: 1.3 V @ 100 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

BZX55C43_T50A FAQ

1.How can I place an order for BZX55C43_T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX55C43_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 BZX55C43_T50A reliable?

The price and inventory of BZX55C43_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX55C43_T50A is usually 5 days.

3.What payment methods are accepted for BZX55C43_T50A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX55C43_T50A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX55C43_T50A?

BZX55C43_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX55C43_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 BZX55C43_T50A?

For technical support, including BZX55C43_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX55C43_T50A requirements.

6.How does Aetrix verify that BZX55C43_T50A is sourced from the original manufacturer or authorized distributors?

All BZX55C43_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 BZX55C43_T50A meets industry standards.

7.What is the process for return or replacement of BZX55C43_T50A?

All BZX55C43_T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX55C43_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 BZX55C43_T50A part is unused and in its original packaging.

Return procedure for BZX55C43_T50A:

1.Submit a request within 90 days.

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

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