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

Diodes Incorporated MMBZ5256B-7-F

Name: MMBZ5256B-7-F
Brand: Diodes Incorporated
SKU: MMBZ5256B-7-F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBZ5256B-7-F

Manufacturer:: Diodes Incorporated

Category:: Single Zener Diodes

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

Datasheet:: MMBZ5256B-7-F.pdf

Description:: DIODE ZENER 30V 350MW SOT23-3

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Product details

Overview

MMBZ5256B-7-F from Diodes Incorporated is a 30V ±5% surface-mount Zener diode in SOT23 package, rated for 350mW power dissipation at +25°C, with 49Ω zener impedance at 4.2mA test current and 0.1µA reverse leakage at 23V, used for precision voltage regulation and overvoltage protection in low-power analog and digital supply rails.

For engineers reviewing the MMBZ5256B-7-F datasheet, MMBZ5256B-7-F pinout, MMBZ5256B-7-F application, or MMBZ5256B-7-F equivalent, this part serves as a stable, RoHS-compliant, lead-free voltage reference in space-constrained PCB designs requiring tight tolerance, low thermal resistance (357°C/W), and compatibility with automated assembly processes.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain a stable 30V reference across its cathode-anode terminals under controlled current conditions. Its planar die construction ensures consistent breakdown characteristics and low parameter drift over temperature.

Designed for operation at I_ZT = 4.2mA, it delivers nominal regulation within ±5% (28.5–31.5V) and exhibits low dynamic impedance (49Ω @ 1kHz), enabling effective noise suppression and transient response in feedback and clamping circuits.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	30V nominal, 28.5–31.5V range at 4.2mA - defines regulated output voltage tolerance for reference and clamp circuits.
Power Dissipation (P_D)	350mW on FR-4 PCB - sets maximum continuous power handling without derating at +25°C ambient.
Zener Impedance (Z_ZT)	49Ω @ 1kHz, 4.2mA - determines AC regulation stability and ripple rejection capability.
Reverse Leakage (I_R)	0.1µA @ 23V - ensures minimal standby current draw in high-impedance bias networks.
Thermal Resistance (R_θJA)	357°C/W - quantifies junction-to-ambient temperature rise per watt, critical for thermal design on standard PCBs.
Package	SOT23 - enables 0.9mm × 2.9mm footprint, compatible with pick-and-place and reflow soldering.
Operating Temperature	−65°C to +150°C - supports industrial and automotive-adjacent environments without derating.

Pinout & Package

Package: SOT23 - surface-mount plastic package with matte tin-plated alloy 42 leadframe, UL 94V-0 rated, moisture sensitivity level 1.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Forward conduction terminal / Zener cathode reference ground	Connected to circuit ground or lower-potential node; reverse-biased operation requires cathode at higher potential.
Cathode (Pin 2)	Zener breakdown terminal / regulated voltage output	Connected to input rail or node requiring clamping/regulation; voltage referenced to anode.
No-Connect (Pin 3)	Non-functional leadframe tie-bar	Internally unconnected; must remain floating or grounded per layout best practices to avoid parasitic coupling.

Key Features

Feature	Design Value
Planar die construction	Ensures repeatable Zener voltage distribution and long-term parametric stability under thermal cycling.
350mW dissipation on FR-4	Enables direct integration into cost-sensitive consumer and industrial PCBs without heatsinking.
Lead-free & RoHS 3 compliant	Meets global environmental compliance requirements including EU Directive 2015/863/EU.
Halogen- and antimony-free "Green" compound	Contains <900ppm Br, <900ppm Cl (<1500ppm total Br+Cl), <1000ppm Sb - supports eco-design standards.
JEDEC-qualified reliability	Validated to high-reliability standards aligned with AEC-Q stress protocols for extended field life.

Applications

Power Supply Rail Clamp

ADC Reference Stabilization

Use Scenario: Clamping 3.3V or 5V logic supply lines against ESD transients and switching spikes in microcontroller peripherals.

IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to limit voltage excursion above 30V while shunting excess current to ground.

Use Value: Prevents latch-up or damage to downstream ICs by limiting peak voltage to ≤30V with sub-µA leakage at normal operating voltage.

Use Scenario: Providing a stable 30V reference for external voltage dividers feeding 12-bit ADC inputs in sensor signal conditioning circuits.

IC Role / Device Role / Timing Role: Passive voltage reference source with low dynamic impedance (49Ω), minimizing noise injection into high-impedance ADC input paths.

Use Value: Enables accurate scaling of ±10V sensor outputs using resistor networks without active buffering, reducing BOM count and board area.

Low-Power Voltage Monitor

Interface Level Translation

Use Scenario: Detecting undervoltage conditions in battery-powered IoT nodes using comparator input biased via resistive divider from 30V Zener.

IC Role / Device Role / Timing Role: Precision threshold generator - fixed 30V reference establishes known trip point independent of supply variation.

Use Value: Delivers ±5% trip accuracy over −40°C to +85°C, eliminating need for trimming or calibration in production.

Use Scenario: Shifting logic levels between 3.3V MCU GPIO and 5V peripheral interface where bidirectional translation is not required.

IC Role / Device Role / Timing Role: Cathode-connected to 5V rail, anode to 3.3V node - conducts only when 5V exceeds 3.3V + V_F, limiting forward voltage swing.

Use Value: Provides simple, passive 5V-to-3.3V level limiting with <0.9V forward drop, avoiding dedicated level-shifter ICs in low-speed control lines.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C30LT1G	Same 30V nominal, ±5% tolerance, but rated for 300mW (vs. 350mW); 60Ω Z_ZT @ 5mA (vs. 49Ω @ 4.2mA).	Lower power rating reduces margin in sustained clamp scenarios; higher Z_ZT degrades AC regulation performance.	Select when legacy BOM alignment or dual-sourcing with ON Semiconductor is required; verify thermal margin at full load.
MM3Z30VT1G	30V, ±5%, 200mW rating, SOD-323 package (smaller footprint); 50Ω Z_ZT @ 5mA - comparable impedance but lower power headroom.	SOD-323 has higher thermal resistance (~450°C/W), limiting usable current in compact layouts.	Prefer for ultra-dense layouts where SOT23 real estate is constrained; confirm derating curves match system ambient conditions.

Compared with BZX84-C30LT1G and MM3Z30VT1G, MMBZ5256B-7-F offers the highest power rating (350mW) and lowest thermal resistance (357°C/W) in SOT23, making it optimal for sustained clamp duty or higher-current reference applications without thermal compromise.

Availability

MMBZ5256B-7-F is available at Aetrix Electronics and suitable for power supply rail protection, ADC reference stabilization, low-power voltage monitoring, and interface level translation requiring stable component supply and JEDEC-qualified reliability.

Supply support for MMBZ5256B-7-F 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

This device belongs to Diodes' MMBZ52xxB series of 350mW Zener diodes, engineered for precision voltage regulation and overvoltage protection in space-constrained, high-volume consumer, industrial, and computing applications.

FAQ

What is the maximum continuous reverse current (I_ZM) for MMBZ5256B-7-F?

The maximum DC zener current is derived from P_D/V_Z = 350mW/30V ≈ 11.7mA. This is the absolute upper limit for continuous operation at +25°C ambient; actual design current should be limited to 4.2mA (IZT) for specified Z_ZT and stability, with derating applied above +25°C per Fig. 1.

Can MMBZ5256B-7-F be used in place of a 24V Zener like MMBZ5242B?

No - MMBZ5256B-7-F is a fixed 30V Zener (28.5–31.5V range) and cannot substitute for 24V regulation. Using it in a 24V circuit would result in excessive voltage drop, increased power dissipation, and potential failure due to mismatched breakdown threshold and thermal loading.

Is the SOT23 package of MMBZ5256B-7-F compatible with standard reflow profiles?

Yes - the device is qualified for Pb-free reflow per J-STD-020, with moisture sensitivity level 1 (unlimited floor life at ≤30°C/60% RH). Standard IPC/JEDEC reflow profiles (peak 260°C, 60-second duration above 217°C) are fully supported with recommended pad layout from Diodes' package outline documentation.

Does MMBZ5256B-7-F meet AEC-Q200 for automotive use?

No - the -7-F suffix denotes commercial-grade qualification. For automotive applications, Diodes offers Q-suffix variants (e.g., MMBZ5256BQ-7-F) qualified to AEC-Q200, manufactured in IATF 16949 facilities, and PPAP-capable. The base part lacks automotive change control and stress testing certification.

MMBZ5256B-7-F Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 30 V

Tolerance:: ±5%

Power - Max:: 350 mW

Impedance (Max) (Zzt):: 49 Ohms

Current - Reverse Leakage @ Vr:: 100 nA @ 23 V

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

Operating Temperature:: -65°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBZ5256B-7-F FAQ

1.How can I place an order for MMBZ5256B-7-F through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBZ5256B-7-F 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 MMBZ5256B-7-F reliable?

The price and inventory of MMBZ5256B-7-F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBZ5256B-7-F is usually 5 days.

3.What payment methods are accepted for MMBZ5256B-7-F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBZ5256B-7-F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBZ5256B-7-F?

MMBZ5256B-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBZ5256B-7-F 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 MMBZ5256B-7-F?

For technical support, including MMBZ5256B-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBZ5256B-7-F requirements.

6.How does Aetrix verify that MMBZ5256B-7-F is sourced from the original manufacturer or authorized distributors?

All MMBZ5256B-7-F 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 MMBZ5256B-7-F meets industry standards.

7.What is the process for return or replacement of MMBZ5256B-7-F?

All MMBZ5256B-7-F units undergo pre-shipment inspection (PSI). If there is an issue with MMBZ5256B-7-F, 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 MMBZ5256B-7-F part is unused and in its original packaging.

Return procedure for MMBZ5256B-7-F:

1.Submit a request within 90 days.

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

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