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

onsemi BZX79C27-T50A

Name: BZX79C27-T50A
Brand: onsemi
SKU: BZX79C27-T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX79C27-T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: BZX79C27-T50A.pdf

Description:: DIODE ZENER 27V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:2,157

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Product details

Overview

BZX79C27-T50A from ON Semiconductor is a 27 V, 5% tolerance, 500 mW DO-35 glass-encapsulated Zener diode optimized for voltage regulation and reference applications in power supply feedback loops, overvoltage protection circuits, and precision biasing networks. It delivers stable 27 V Zener voltage at 2 mA test current with 80 Ω dynamic impedance and operates across –65°C to +200°C.

For engineers reviewing the BZX79C27-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance (±5%), thermal coefficient (–2.5 mV/°C), leakage current (≤0.05 µA at 20.3 V), and DO-35 package compatibility with through-hole PCB assembly and manual rework workflows.

Technical Context

The BZX79C27-T50A functions as a two-terminal voltage reference device operating in reverse breakdown mode. Its Zener voltage is specified at 2 mA (IZ = 2 mA), with dynamic impedance of 80 Ω measured under those conditions and temperature coefficient of –2.5 mV/°C - indicating negative drift with rising junction temperature.

It exhibits low leakage current (≤0.05 µA at VR = 20.3 V), supports continuous power dissipation up to 500 mW at TL ≤ 75°C, and derates linearly at 4.0 mW/°C above that lead temperature - enabling predictable thermal design in compact linear regulator or clamp circuits.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	27 V ±5% at I_Z = 2 mA - defines nominal regulation point with 1.35 V total tolerance band
Power Dissipation (P_D)	500 mW @ T_L ≤ 75°C - sets maximum steady-state power handling before thermal derating begins
Dynamic Impedance (Z_Z)	80 Ω @ I_Z = 2 mA - determines output voltage variation under load current changes
Temperature Coefficient (TC)	–2.5 mV/°C - quantifies voltage drift per degree rise in junction temperature
Leakage Current (I_R)	≤0.05 µA @ V_R = 20.3 V - ensures minimal error current in high-impedance reference nodes
Junction Temperature Range	–65°C to +200°C - enables operation in automotive under-hood, industrial motor control, and aerospace environments

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 soldering and hand assembly. Package dimensions conform to JEDEC DO-35 standard: overall length 4.0–5.2 mm, diameter 1.8–2.2 mm, lead diameter 0.4–0.6 mm.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Reference ground node in shunt regulator	Connected to circuit ground or lower-potential rail; carries reverse leakage and Zener current when regulating
Cathode	Zener breakdown terminal / Regulated output node	Connected to input voltage source via series resistor; maintains stable 27 V relative to anode during breakdown

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables tight regulation without post-production trimming in cost-sensitive consumer and industrial supplies
Low 0.05 µA leakage at 75% V_Z	Minimizes error in high-resistance divider networks used for feedback sensing
–2.5 mV/°C temperature coefficient	Supports predictable compensation in temperature-stable references when paired with positive-TC components
DO-35 glass package with cathode band	Provides visual polarity identification and hermetic sealing for long-term reliability in humid or corrosive environments

Applications

Switch-Mode Power Supply Feedback	Overvoltage Clamp Protection
Use Scenario: Used in optocoupler-coupled feedback loop of isolated DC-DC converters to regulate output voltage. IC Role / Device Role / Timing Role: Zener reference element setting precise 27 V threshold for TL431-like comparator action. Use Value: Tight 5% tolerance ensures ±1.35 V regulation accuracy; low leakage avoids loading of high-impedance feedback divider.	Use Scenario: Placed across sensitive IC inputs to limit transient overvoltage from ESD or inductive kickback. IC Role / Device Role / Timing Role: Shunt clamping device diverting surge current above 27 V to ground. Use Value: Fast response (<1 ns) and 80 Ω Z_Z ensure clamping within safe voltage margin; DO-35 robustness withstands repeated surges.
Linear Voltage Reference	Microcontroller Reset Circuit
Use Scenario: Provides stable 27 V reference for analog-to-digital converter calibration or sensor excitation. IC Role / Device Role / Timing Role: Precision voltage source establishing known potential for ratiometric measurements. Use Value: –2.5 mV/°C TC allows predictable drift modeling; 200°C max T_J supports operation in sealed enclosures.	Use Scenario: Monitors main supply rail and triggers MCU reset when voltage drops below 27 V × 0.9 = 24.3 V. IC Role / Device Role / Timing Role: Threshold detector in discrete reset generator using resistor divider and transistor switch. Use Value: Low 0.05 µA leakage prevents false triggering; DO-35 form factor fits legacy reset board layouts.

Switch-Mode Power Supply Feedback

Overvoltage Clamp Protection

Use Scenario: Used in optocoupler-coupled feedback loop of isolated DC-DC converters to regulate output voltage.

IC Role / Device Role / Timing Role: Zener reference element setting precise 27 V threshold for TL431-like comparator action.

Use Value: Tight 5% tolerance ensures ±1.35 V regulation accuracy; low leakage avoids loading of high-impedance feedback divider.

Use Scenario: Placed across sensitive IC inputs to limit transient overvoltage from ESD or inductive kickback.

IC Role / Device Role / Timing Role: Shunt clamping device diverting surge current above 27 V to ground.

Use Value: Fast response (<1 ns) and 80 Ω Z_Z ensure clamping within safe voltage margin; DO-35 robustness withstands repeated surges.

Linear Voltage Reference

Microcontroller Reset Circuit

Use Scenario: Provides stable 27 V reference for analog-to-digital converter calibration or sensor excitation.

IC Role / Device Role / Timing Role: Precision voltage source establishing known potential for ratiometric measurements.

Use Value: –2.5 mV/°C TC allows predictable drift modeling; 200°C max T_J supports operation in sealed enclosures.

Use Scenario: Monitors main supply rail and triggers MCU reset when voltage drops below 27 V × 0.9 = 24.3 V.

IC Role / Device Role / Timing Role: Threshold detector in discrete reset generator using resistor divider and transistor switch.

Use Value: Low 0.05 µA leakage prevents false triggering; DO-35 form factor fits legacy reset board layouts.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4750A	Same 27 V rating, ±5% tolerance, but 1 W power rating and DO-41 package	Higher power handling supports higher-current clamping; larger DO-41 footprint requires PCB redesign	Select when >500 mW dissipation or improved thermal margin is required
BZX55C27	Same 27 V, ±5%, DO-35, but 500 mW rating and 100 Ω Z_Z @ 5 mA	Higher dynamic impedance reduces regulation precision; identical mounting and layout compatibility	Select when legacy BOM uses BZX55 series and minor Z_Z increase is acceptable

Compared with 1N4750A and BZX55C27, the BZX79C27-T50A offers optimal balance of DO-35 footprint, 80 Ω Z_Z, and –2.5 mV/°C TC for space-constrained, precision-regulation designs where thermal derating and leakage are critical.

Availability

BZX79C27-T50A is available at Aetrix Electronics and suitable for switch-mode power supply feedback, overvoltage clamp protection, and microcontroller reset circuits requiring stable component supply and long-lifecycle support.

Supply support for BZX79C27-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, sensors, and logic solutions for automotive, industrial, cloud computing, and consumer markets.

The BZX79C series was designed specifically for general-purpose voltage regulation and reference applications where reliability, tight tolerance, and wide temperature range are essential - particularly in cost-sensitive, high-volume power supply designs.

FAQ

What is the Zener voltage tolerance of the BZX79C27-T50A?

The BZX79C27-T50A has a Zener voltage tolerance of ±5% at I_Z = 2 mA, resulting in a guaranteed range of 25.65 V to 28.35 V. This tolerance is tested and binned during manufacturing, and applies across the full operating temperature range of –65°C to +200°C. The BZX79C27-T50A datasheet specifies this value under "Electrical Characteristics" with note referencing 5% tolerance for the entire BZX79C2V4–BZX79C56 family.

What is the maximum power dissipation for the BZX79C27-T50A?

The BZX79C27-T50A has a maximum power dissipation of 500 mW at lead temperature (T_L) ≤ 75°C with 3/8″ lead length. Above 75°C, it derates linearly at 4.0 mW/°C. This rating is defined in the Absolute Maximum Ratings table and reflects thermal limits of the DO-35 glass package. Exceeding this limit risks irreversible junction damage, so proper PCB copper area and ambient airflow must be considered in the BZX79C27-T50A layout.

Does the BZX79C27-T50A have a specified temperature coefficient?

Yes, the BZX79C27-T50A has a temperature coefficient of –2.5 mV/°C, meaning its Zener voltage decreases by 2.5 mV per degree Celsius rise in junction temperature. This value is explicitly listed in the Electrical Characteristics table for the BZX79C27 variant. The negative sign indicates inverse correlation between temperature and V_Z, which is typical for Zeners above ~5 V - a key parameter for stability analysis in the BZX79C27-T50A's target applications.

What is the dynamic impedance of the BZX79C27-T50A and why does it matter?

The BZX79C27-T50A has a dynamic impedance (Z_Z) of 80 Ω at I_Z = 2 mA. This parameter quantifies how much the Zener voltage changes in response to small variations in current - lower Z_Z means better regulation. For example, a 1 mA change causes only ~80 mV shift in output voltage. This value directly impacts performance in the BZX79C27-T50A's use as a voltage reference, especially in feedback networks where load transients occur.

How is polarity identified on the BZX79C27-T50A package?

The BZX79C27-T50A uses a cathode band - a single colored ring near one end of the DO-35 glass body - to identify the cathode terminal. The unmarked end is the anode. This marking follows JEDEC standard DO-35 conventions and is confirmed in the "Top Mark Information" section of the ON Semiconductor datasheet. Correct orientation is critical: reverse connection prevents Zener operation and may cause forward conduction failure in the BZX79C27-T50A.

BZX79C27-T50A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Cut Tape (CT)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 27 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 80 Ohms

Current - Reverse Leakage @ Vr:: 50 nA @ 18.9 V

Voltage - Forward (Vf) (Max) @ If:: 1.5 V @ 100 mA

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

BZX79C27-T50A FAQ

1.How can I place an order for BZX79C27-T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX79C27-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 BZX79C27-T50A reliable?

The price and inventory of BZX79C27-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX79C27-T50A is usually 5 days.

3.What payment methods are accepted for BZX79C27-T50A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX79C27-T50A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX79C27-T50A?

BZX79C27-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX79C27-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 BZX79C27-T50A?

For technical support, including BZX79C27-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX79C27-T50A requirements.

6.How does Aetrix verify that BZX79C27-T50A is sourced from the original manufacturer or authorized distributors?

All BZX79C27-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 BZX79C27-T50A meets industry standards.

7.What is the process for return or replacement of BZX79C27-T50A?

All BZX79C27-T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX79C27-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 BZX79C27-T50A part is unused and in its original packaging.

Return procedure for BZX79C27-T50A:

1.Submit a request within 90 days.

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

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