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

onsemi BZX85C33

Name: BZX85C33
Brand: onsemi
SKU: BZX85C33
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX85C33

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: BZX85C33.pdf

Description:: DIODE ZENER 33V 1W DO41

Quantity:: RFQ Add To RFQ list

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Inventory:2,490

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Product details

Overview

BZX85C33 from onsemi is a 33 V, ±5% tolerance, 1.0 W axial-leaded Zener diode in DO-41 glass package, designed for voltage regulation and reference applications with 8 Ω dynamic impedance at 35 mA and 0.25 μA maximum leakage at 23 V reverse bias.

For engineers reviewing the BZX85C33 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy, power dissipation capability, thermal derating behavior, and DO-41 mechanical compatibility in low-to-medium power analog circuits.

Technical Context

The BZX85C33 operates as a silicon planar Zener diode with sharp reverse breakdown at nominal 33 V, specified under thermal equilibrium conditions at 30°C lead temperature and 3/8″ lead length. Its 1.0 W power rating at 25°C ambient is thermally derated at 6.67 mW/°C above 50°C.

It exhibits 8 Ω Zener impedance (ZZ) at IZ = 35 mA and 1000 Ω knee impedance (ZZK) at IZK = 0.5 mA, with forward voltage ≤1.2 V at 200 mA. The device supports operation across –65°C to +200°C junction and storage temperature range.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	31 V min / 35 V max - defines stable regulation window for precision reference use
Power Dissipation (P_D)	1.0 W @ T_A = 25°C - sets maximum continuous DC power handling in free-air
Zener Impedance (Z_Z)	8 Ω @ I_Z = 35 mA - indicates low AC impedance for stable regulation under load variation
Knee Impedance (Z_ZK)	1000 Ω @ I_ZK = 0.5 mA - reflects higher impedance near breakdown threshold, affecting low-current stability
Leakage Current (I_R)	0.25 μA max @ V_R = 23 V - ensures minimal standby current in high-impedance bias networks
Forward Voltage (V_F)	≤1.2 V @ I_F = 200 mA - enables use as low-drop rectifier or clamp in dual-polarity designs
Operating Temperature	–65°C to +200°C - supports deployment in automotive under-hood, industrial control, and aerospace environments

Pinout & Package

DO-41 glass axial package with cathode indicated by color band; two-terminal device requiring no external biasing circuitry beyond series current-limiting resistor.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Positive terminal in forward bias; connected to lower potential in Zener regulation	Accepts forward current up to 200 mA; forms low-voltage drop path when conducting
Cathode	Negative terminal in forward bias; connected to higher potential in Zener regulation	Provides stable 33 V reference when reverse-biased; marked by visible band on DO-41 body

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables predictable regulation without post-production trimming in cost-sensitive consumer and industrial supplies
1.0 W power rating with linear derating	Supports robust transient energy absorption and sustained DC regulation in 12–48 V systems
DO-41 glass package	Provides hermetic sealing, high reliability, and JEDEC-standard footprint for manual or wave soldering
Low leakage at 23 V	Minimizes error in high-resistance voltage divider references and battery-monitoring circuits
Specified Z_Z and Z_ZK	Allows accurate modeling of regulation deviation across operating current range from 0.5 mA to 35 mA

Applications

DC Power Supply Regulation	Voltage Reference Circuit
Use Scenario: Stabilizing unregulated 36–40 V DC rail in linear regulator front-end or auxiliary supply. IC Role / Device Role / Timing Role: Zener diode acting as shunt voltage reference and overvoltage clamp. Use Value: Maintains output within ±5% of 33 V across load currents up to 30 mA with <8 Ω dynamic impedance.	Use Scenario: Providing precise 33 V reference for ADC input scaling or comparator threshold setting. IC Role / Device Role / Timing Role: Passive voltage reference element in high-impedance divider network. Use Value: Delivers stable reference with ≤0.25 μA leakage, minimizing offset error in 1 MΩ+ bias networks.
Overvoltage Protection	Signal Level Clamping
Use Scenario: Protecting microcontroller I/O pins against 36 V transients on 3.3 V or 5 V logic lines. IC Role / Device Role / Timing Role: Bidirectional clamping device (forward + reverse conduction). Use Value: Limits voltage to ≤34.2 V (33 V + 1.2 V forward drop) during surge events without latch-up.	Use Scenario: Constraining analog sensor output swing to safe range before feeding into op-amp input stage. IC Role / Device Role / Timing Role: Reverse-biased Zener limiting positive excursion; forward conduction limiting negative. Use Value: Clamps signal between –1.2 V and +34.2 V with predictable knee behavior at 0.5 mA.

DC Power Supply Regulation

Voltage Reference Circuit

Use Scenario: Stabilizing unregulated 36–40 V DC rail in linear regulator front-end or auxiliary supply.

IC Role / Device Role / Timing Role: Zener diode acting as shunt voltage reference and overvoltage clamp.

Use Value: Maintains output within ±5% of 33 V across load currents up to 30 mA with <8 Ω dynamic impedance.

Use Scenario: Providing precise 33 V reference for ADC input scaling or comparator threshold setting.

IC Role / Device Role / Timing Role: Passive voltage reference element in high-impedance divider network.

Use Value: Delivers stable reference with ≤0.25 μA leakage, minimizing offset error in 1 MΩ+ bias networks.

Overvoltage Protection

Signal Level Clamping

Use Scenario: Protecting microcontroller I/O pins against 36 V transients on 3.3 V or 5 V logic lines.

IC Role / Device Role / Timing Role: Bidirectional clamping device (forward + reverse conduction).

Use Value: Limits voltage to ≤34.2 V (33 V + 1.2 V forward drop) during surge events without latch-up.

Use Scenario: Constraining analog sensor output swing to safe range before feeding into op-amp input stage.

IC Role / Device Role / Timing Role: Reverse-biased Zener limiting positive excursion; forward conduction limiting negative.

Use Value: Clamps signal between –1.2 V and +34.2 V with predictable knee behavior at 0.5 mA.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N5256B	33 V, ±5%, 0.5 W, DO-35 package, 25 Ω Z_Z @ 10 mA	Lower power rating and higher impedance limit use in higher-current regulation	Preferred where board space is constrained and power demand ≤250 mW
MMBZ5256BS	33 V, ±5%, 0.3 W, SOT-23 package, 25 Ω Z_Z @ 10 mA	Surface-mount form factor and reduced power require redesign of thermal layout and current limiting	Selected for automated assembly and compact PCB layouts where 1.0 W dissipation is not required

Compared with BZX85C33, the 1N5256B offers identical voltage rating but lower power and higher impedance, while the MMBZ5256BS trades package format and thermal capacity for SMT compatibility-both serve as functional alternatives only when power, impedance, and mounting constraints align.

Availability

BZX85C33 is available at Aetrix Electronics and suitable for DC power supply regulation, voltage reference circuits, overvoltage protection, and signal level clamping requiring stable component supply and long-term manufacturability.

Supply support for BZX85C33 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BZX85C33 belongs to the BZX85C series of general-purpose Zener diodes engineered for reliable voltage regulation and reference functions in cost-sensitive, medium-power analog and power supply designs.

FAQ

What is the Zener voltage tolerance of the BZX85C33?

The BZX85C33 has a nominal Zener voltage of 33 V with a guaranteed tolerance of ±5%, meaning its actual breakdown voltage falls between 31 V and 35 V at test conditions (T_L = 30°C, 3/8″ lead length). This tolerance is confirmed in the Electrical Characteristics table of the official onsemi datasheet (Rev. 2, October 2017) and applies across the full operating temperature range.

Can the BZX85C33 be used in surface-mount designs?

No, the BZX85C33 is packaged in the axial DO-41 glass case and requires through-hole mounting. It is not compatible with SMT reflow or pick-and-place processes. For surface-mount equivalents, consider the MMBZ5256BS or similar SOT-23 Zener diodes-but note their lower 0.3 W power rating and different thermal behavior compared to the BZX85C33.

What is the maximum leakage current for the BZX85C33 at 23 V?

The BZX85C33 specifies a maximum leakage current (I_R) of 0.25 μA at V_R = 23 V, per the Electrical Characteristics table. This value is measured at T_A = 25°C and reflects the diode's ability to maintain high impedance below its Zener knee, critical for precision reference and low-power biasing applications.

How does thermal derating apply to the BZX85C33?

The BZX85C33 is rated for 1.0 W at T_A = 25°C, with linear derating beginning at 50°C at 6.67 mW/°C. At 100°C ambient, its usable power drops to approximately 667 mW. This derating must be applied in PCB layout decisions-especially when multiple devices share heatsinking or operate in enclosed enclosures.

Is the BZX85C33 suitable for bidirectional clamping?

Yes-the BZX85C33 conducts in forward bias with V_F ≤1.2 V at 200 mA and regulates in reverse bias at ~33 V, enabling effective bidirectional clamping between –1.2 V and +34.2 V. This dual-mode behavior is explicitly supported by its forward voltage specification and Zener characteristics, making it suitable for protecting sensitive inputs against both polarity transients.

BZX85C33 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 33 V

Tolerance:: ±6%

Power - Max:: 1 W

Impedance (Max) (Zzt):: 35 Ohms

Current - Reverse Leakage @ Vr:: 500 nA @ 23 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-41

BZX85C33 FAQ

1.How can I place an order for BZX85C33 through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX85C33 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 BZX85C33 reliable?

The price and inventory of BZX85C33 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX85C33 is usually 5 days.

3.What payment methods are accepted for BZX85C33?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX85C33 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX85C33?

BZX85C33 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX85C33 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 BZX85C33?

For technical support, including BZX85C33 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX85C33 requirements.

6.How does Aetrix verify that BZX85C33 is sourced from the original manufacturer or authorized distributors?

All BZX85C33 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 BZX85C33 meets industry standards.

7.What is the process for return or replacement of BZX85C33?

All BZX85C33 units undergo pre-shipment inspection (PSI). If there is an issue with BZX85C33, 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 BZX85C33 part is unused and in its original packaging.

Return procedure for BZX85C33:

1.Submit a request within 90 days.

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

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