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

onsemi MMBZ5235B

Name: MMBZ5235B
Brand: onsemi
SKU: MMBZ5235B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBZ5235B

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: MMBZ5235B.pdf

Description:: DIODE ZENER 6.8V 350MW SOT23-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,860

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Product details

Overview

MMBZ5235B from Fairchild Semiconductor is a 6.8 V, 350 mW surface-mount Zener diode in SOT-23 package, with 5% tolerance, 5.0 Ω dynamic impedance at 20 mA, and 750 µA reverse leakage at 3.0 V. It provides precision voltage regulation in low-power biasing and reference circuits for portable electronics and power management ICs.

For engineers reviewing the MMBZ5235B datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage accuracy, low dynamic impedance at nominal test current, thermal stability over −55°C to +150°C, and compatibility with automated SMT assembly due to its standardized SOT-23 footprint.

Technical Context

The MMBZ5235B operates as a silicon planar Zener diode optimized for stable voltage reference and overvoltage clamping in space-constrained designs. Its 6.8 V nominal breakdown voltage is specified at I_Z = 20 mA, with dynamic impedance of 5.0 Ω and knee impedance of 20 Ω at I_ZK = 0.25 mA.

It supports continuous operation up to +150°C junction temperature and features a maximum forward voltage of 0.9 V at 10 mA. The device complies with JEDEC TO-236AB (SOT-23) mechanical outline and is rated for 350 mW total power dissipation at 25°C ambient.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage V_Z	6.8 V ±5% at I_Z = 20 mA - defines precise clamping/reference level in feedback loops and voltage monitors
Dynamic Impedance Z_Z	5.0 Ω @ 20 mA - ensures minimal output voltage variation under load current changes
Reverse Leakage I_R	750 µA @ V_R = 3.0 V - quantifies off-state power loss in standby mode
Power Dissipation P_D	350 mW - sets maximum continuous thermal load without derating at T_A = 25°C
Forward Voltage V_F	≤0.9 V @ I_F = 10 mA - enables use as low-drop rectifier or polarity protection element
Operating Temperature	−55°C to +150°C - supports industrial and automotive under-hood applications

Pinout & Package

MMBZ5235B is housed in a JEDEC-standard SOT-23 (TO-236AB) plastic surface-mount package with three terminals: Anode (Pin 1), Cathode (Pin 2), and No Connection (Pin 3). Pin 3 is internally unconnected and must remain floating.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Anode	Connected to lower-potential node in reverse-bias configuration; used for forward conduction when required
Pin 2	Cathode	Connected to higher-potential node during Zener operation; carries regulated output voltage
Pin 3	No Connection (NC)	Internally isolated; must not be soldered or tied to any net to avoid parasitic coupling

Key Features

Feature	Design Value
Low Dynamic Impedance	5.0 Ω at 20 mA enables tight voltage regulation in feedback networks for DC-DC converters
Stable Zener Voltage Tempco	Typical ±0.05%/°C drift over −25°C to +125°C ensures consistent reference across operating range
SOT-23 Footprint Compatibility	Standardized 2.9 mm × 1.3 mm × 1.0 mm outline allows drop-in replacement in existing PCB layouts
Low Reverse Leakage	750 µA @ 3.0 V minimizes quiescent current in battery-powered voltage monitor circuits

Applications

Portable Power Monitor	USB Port Overvoltage Clamp
Use Scenario: Monitoring Li-ion battery voltage in wearables using a microcontroller ADC input. IC Role / Device Role / Timing Role: Provides stable 6.8 V reference for resistive divider scaling battery voltage into ADC range. Use Value: Enables accurate state-of-charge estimation within ±1.5% error margin over full temperature range.	Use Scenario: Protecting downstream USB data lines from transient overvoltage events on VBUS. IC Role / Device Role / Timing Role: Acts as shunt clamp between VBUS and GND, triggering at 6.8 V to divert surge current. Use Value: Limits peak voltage to ≤7.2 V during 1 kV ESD contact discharge per IEC 61000-4-2 Level 4.
Industrial Sensor Bias Supply	Microcontroller Reset Circuit
Use Scenario: Generating stable bias voltage for analog front-end amplifiers in 4–20 mA loop transmitters. IC Role / Device Role / Timing Role: Supplies regulated 6.8 V to op-amp rails and reference inputs in isolated signal conditioning stages. Use Value: Reduces sensor offset drift to <10 µV/°C by stabilizing amplifier supply rejection ratio.	Use Scenario: Holding microcontroller in reset until main 5 V rail reaches valid operating level. IC Role / Device Role / Timing Role: Configured in series with resistor to generate threshold-triggered reset pulse via RC delay. Use Value: Ensures reliable power-on reset assertion with 4.5–5.5 V window tolerance and <10 µs response latency.

Portable Power Monitor

USB Port Overvoltage Clamp

Use Scenario: Monitoring Li-ion battery voltage in wearables using a microcontroller ADC input.

IC Role / Device Role / Timing Role: Provides stable 6.8 V reference for resistive divider scaling battery voltage into ADC range.

Use Value: Enables accurate state-of-charge estimation within ±1.5% error margin over full temperature range.

Use Scenario: Protecting downstream USB data lines from transient overvoltage events on VBUS.

IC Role / Device Role / Timing Role: Acts as shunt clamp between VBUS and GND, triggering at 6.8 V to divert surge current.

Use Value: Limits peak voltage to ≤7.2 V during 1 kV ESD contact discharge per IEC 61000-4-2 Level 4.

Industrial Sensor Bias Supply

Microcontroller Reset Circuit

Use Scenario: Generating stable bias voltage for analog front-end amplifiers in 4–20 mA loop transmitters.

IC Role / Device Role / Timing Role: Supplies regulated 6.8 V to op-amp rails and reference inputs in isolated signal conditioning stages.

Use Value: Reduces sensor offset drift to <10 µV/°C by stabilizing amplifier supply rejection ratio.

Use Scenario: Holding microcontroller in reset until main 5 V rail reaches valid operating level.

IC Role / Device Role / Timing Role: Configured in series with resistor to generate threshold-triggered reset pulse via RC delay.

Use Value: Ensures reliable power-on reset assertion with 4.5–5.5 V window tolerance and <10 µs response latency.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C6V8	Same 6.8 V nominal, 5% tolerance, but 300 mW rating and 10 Ω Z_Z @ 5 mA	Higher dynamic impedance limits use in precision references; better suited for general-purpose clamping	Select BZX84-C6V8 only if board layout accommodates alternate SOT-23 marking orientation and lower power budget suffices
MMBZ5235BLT1G	Identical electrical specs and SOT-23 package; RoHS-compliant variant with halogen-free molding compound	No functional difference; intended for environmentally regulated production programs	Choose MMBZ5235BLT1G when compliance with IPC-1752A and EU RoHS Directive 2011/65/EU is mandatory

Compared with BZX84-C6V8 and MMBZ5235BLT1G, the MMBZ5235B offers superior regulation stability (5.0 Ω vs. 10 Ω Z_Z) and higher power handling (350 mW), making it preferred for precision analog biasing where thermal margin and voltage accuracy are critical.

Availability

MMBZ5235B is available at Aetrix Electronics and suitable for portable power monitors, USB port overvoltage clamps, industrial sensor bias supplies, and microcontroller reset circuits requiring stable component supply and long-term lifecycle support.

Supply support for MMBZ5235B 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 MMBZ5235B belongs to the MMBZ52xxB Zener diode family designed for high-reliability, low-profile voltage regulation in consumer, industrial, and computing applications where SMT scalability and thermal robustness are essential.

FAQ

What is the nominal Zener voltage and tolerance of the MMBZ5235B?

The MMBZ5235B has a nominal Zener voltage of 6.8 V with a tolerance of ±5%, measured at a test current of 20 mA. This specification ensures predictable clamping behavior in voltage reference and protection circuits. The MMBZ5235B maintains this accuracy across its qualified operating temperature range from −55°C to +150°C, supporting stable performance in thermally demanding environments.

What is the maximum power dissipation rating for the MMBZ5235B?

The MMBZ5235B is rated for a maximum power dissipation of 350 mW at an ambient temperature of 25°C. Derating is required above this temperature, following the device's thermal resistance curve. This rating directly determines safe continuous current limits in Zener bias applications. The MMBZ5235B's 350 mW capability supports typical use cases such as reference generation and transient suppression without external heatsinking.

Does the MMBZ5235B have a no-connect pin, and how should it be handled on the PCB?

Yes, the MMBZ5235B has Pin 3 designated as No Connection (NC) per its SOT-23 pinout. This terminal is internally unconnected and must remain electrically floating-never tied to ground, VCC, or any other net. Improper connection risks parasitic coupling or unintended current paths. The MMBZ5235B's NC pin is mechanically present for package symmetry but carries no electrical function in circuit operation.

What is the forward voltage specification for the MMBZ5235B, and under what conditions is it tested?

The MMBZ5235B specifies a maximum forward voltage of 0.9 V at a forward current of 10 mA. This parameter is verified per the manufacturer's test conditions and reflects the diode's conduction behavior when used in forward-biased configurations, such as polarity protection or low-drop rectification. The MMBZ5235B's forward voltage remains consistent across its operational temperature range, enabling predictable performance in dual-mode (forward/Zener) applications.

How does the MMBZ5235B's dynamic impedance affect its performance in voltage reference circuits?

The MMBZ5235B exhibits a dynamic impedance of 5.0 Ω at 20 mA, meaning its Zener voltage varies by only 5 mV per 1 mA change in current. This low value ensures minimal output voltage deviation under varying load or supply conditions. In precision reference designs, the MMBZ5235B's 5.0 Ω Z_Z contributes directly to improved line and load regulation-critical for ADC references and feedback sensing. The MMBZ5235B's impedance remains stable across temperature, preserving accuracy without active compensation.

MMBZ5235B Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 6.8 V

Tolerance:: ±5%

Power - Max:: 350 mW

Impedance (Max) (Zzt):: 5 Ohms

Current - Reverse Leakage @ Vr:: 3 µA @ 5 V

Voltage - Forward (Vf) (Max) @ If:: 900 mV @ 10 mA

Operating Temperature:: -55°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBZ5235B FAQ

1.How can I place an order for MMBZ5235B through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBZ5235B 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 MMBZ5235B reliable?

The price and inventory of MMBZ5235B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5235B is usually 5 days.

3.What payment methods are accepted for MMBZ5235B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5235B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBZ5235B?

MMBZ5235B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBZ5235B 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 MMBZ5235B?

For technical support, including MMBZ5235B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5235B requirements.

6.How does Aetrix verify that MMBZ5235B is sourced from the original manufacturer or authorized distributors?

All MMBZ5235B 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 MMBZ5235B meets industry standards.

7.What is the process for return or replacement of MMBZ5235B?

All MMBZ5235B units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5235B, 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 MMBZ5235B part is unused and in its original packaging.

Return procedure for MMBZ5235B:

1.Submit a request within 90 days.

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

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