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

Diodes Incorporated MMSZ5255B-7-F

Name: MMSZ5255B-7-F
Brand: Diodes Incorporated
SKU: MMSZ5255B-7-F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMSZ5255B-7-F

Manufacturer:: Diodes Incorporated

Category:: Single Zener Diodes

Package:: SOD-123

Datasheet:: MMSZ5255B-7-F.pdf

Description:: DIODE ZENER 28V 500MW SOD123

Quantity:: RFQ Add To RFQ list

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Inventory:32,993

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Product details

Overview

MMSZ5255B-7-F from Diodes Incorporated is a 28 V, ±3.5% tolerance, 500 mW surface-mount Zener diode in SOD123 package, rated for 4.5 mA test current and 44 Ω dynamic impedance at 1 kHz, used for precision voltage regulation and overvoltage protection in low-power analog and power-supply feedback circuits.

For engineers reviewing the MMSZ5255B-7-F datasheet, MMSZ5255B-7-F pinout, MMSZ5255B-7-F application, or MMSZ5255B-7-F equivalent, key selection criteria include nominal Zener voltage (28 V), tight tolerance (±3.5%), low leakage (<0.1 µA at 21 V), thermal stability (TC ≈ +0.07%/°C), and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This Zener diode operates in reverse breakdown mode with a nominal Zener voltage of 28 V at 4.5 mA test current, exhibiting 44 Ω impedance at 1 kHz and <0.1 µA reverse leakage at VR = 21 V. Its temperature coefficient is approximately +0.07%/°C, indicating positive drift with rising junction temperature.

Designed for stable voltage reference in space-constrained PCB layouts, it delivers 370 mW power dissipation at 25°C ambient and derates linearly to 500 mW at 75°C lead temperature. The SOD123 package supports automated pick-and-place assembly and meets J-STD-020 Level 1 moisture sensitivity.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	28 V nominal, 26.6–29.4 V range at 4.5 mA - defines regulated output voltage in shunt regulator or reference circuits
Power Dissipation (P_D)	370 mW @ T_A = 25°C - maximum continuous power under standard board conditions (FR-4, 1″ copper pad)
Zener Impedance (Z_ZT)	44 Ω @ f = 1 kHz - determines AC regulation accuracy and ripple rejection in feedback paths
Reverse Leakage (I_R)	<0.1 µA @ V_R = 21 V - ensures minimal quiescent current in standby or battery-powered applications
Tolerance	±3.5% - enables predictable voltage setting without post-assembly trimming in production
Thermal Resistance (R_θJA)	338 °C/W - informs thermal design margin when operating near max power on standard PCB layout

Pinout & Package

Package: SOD123 - surface-mount plastic case with cathode band marking, 1.05 mm height, 2.65 mm width, and 3.65 mm length; compatible with reflow soldering per J-STD-020 Level 1.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Zener cathode reference node	Connected to lower-potential side of circuit; forms reference ground return path in shunt regulators
Cathode	Reverse-biased Zener terminal / voltage regulation node	Connected to regulated rail; clamps voltage at 28 V when reverse current exceeds knee threshold

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive electronics use with extended temperature operation (−65°C to +150°C)
Green compound packaging	Halogen- and antimony-free molding compound meeting RoHS 2 and UL 94V-0 flammability rating
Low leakage performance	<0.1 µA at 75% of V_Z - minimizes error in high-impedance reference networks
Automated assembly compatibility	SOD123 footprint optimized for high-yield pick-and-place and reflow processes

Applications

Power Supply Feedback

Overvoltage Clamp

Use Scenario: Regulating output voltage in isolated flyback or buck converter feedback loops using optocoupler-coupled TL431 alternatives.

IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 28 V reference for error amplifier biasing.

Use Value: Enables accurate ±3.5% output regulation without external trimming, reducing BOM count and calibration cost.

Use Scenario: Protecting microcontroller I/O pins or ADC inputs from transient overvoltage events in industrial sensor interfaces.

IC Role / Device Role / Timing Role: Fast-acting clamp limiting input voltage to 28 V during ESD or surge events.

Use Value: Prevents latch-up or damage with sub-µA leakage below clamp threshold and 44 Ω dynamic impedance for rapid energy dissipation.

Reference Voltage Source

Automotive Body Control Module

Use Scenario: Generating stable bias voltages for op-amp comparators or analog front-ends in battery-powered instrumentation.

IC Role / Device Role / Timing Role: Precision Zener reference replacing higher-cost IC references where 28 V is required.

Use Value: Delivers 28 V reference with <0.1 µA leakage and +0.07%/°C TC, enabling low-drift designs across −40°C to +125°C.

Use Scenario: Providing regulated 28 V supply for LIN transceiver biasing or LED driver enable logic in vehicle lighting modules.

IC Role / Device Role / Timing Role: AEC-Q101-compliant voltage clamp ensuring functional safety compliance in 12 V/24 V dual-battery systems.

Use Value: Guarantees operation over full automotive temperature range and vibration profile without derating or redundancy.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX584C27LT1G	27 V nominal, ±5% tolerance, 300 mW P_D, SOD-523 package	Lower power rating and smaller footprint; less thermal mass limits surge handling	Select when board space is critical and 27 V suffices; verify thermal margin under peak load
MMBZ5255BS	28 V nominal, ±5% tolerance, 300 mW P_D, SOT-23 package	Higher leakage (≤1 µA at 21 V) and larger package footprint than SOD123	Prefer for legacy SOT-23 layouts; avoid in low-leakage or high-reliability automotive designs

Compared with BZX584C27LT1G and MMBZ5255BS, MMSZ5255B-7-F offers tighter tolerance (±3.5% vs. ±5%), higher power rating (370 mW vs. 300 mW), and AEC-Q101 qualification-making it optimal for automotive and precision industrial voltage reference use cases.

Availability

MMSZ5255B-7-F is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor signal conditioning, and medical portable device power management requiring stable component supply and long-term lifecycle support.

Supply support for MMSZ5255B-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, specializing in high-reliability components for automotive, industrial, and consumer markets.

MMSZ5255B-7-F belongs to the MMSZ52xxB series of general-purpose Zener diodes engineered for medium-current voltage regulation and overvoltage protection in compact, automated-assembly environments.

FAQ

What is the maximum reverse voltage before breakdown for MMSZ5255B-7-F?

The nominal Zener voltage is 28 V with a guaranteed range of 26.6 V to 29.4 V at 4.5 mA test current. Breakdown begins near the lower limit (26.6 V), and full regulation occurs above 27 V. Operation below 26.6 V results in negligible reverse current (<0.1 µA).

Can MMSZ5255B-7-F be used in place of a 27 V Zener diode?

No-MMSZ5255B-7-F is specifically rated for 28 V nominal regulation. Substituting it for a 27 V part introduces a 1 V offset that may cause overvoltage in feedback loops or exceed absolute maximum ratings of downstream devices. Use MMSZ5254B-7-F (27 V) instead.

Is thermal derating required when operating at 85°C ambient?

Yes. At 85°C ambient, power dissipation must be reduced to ~250 mW based on the 338 °C/W R_θJA and 150°C max junction temperature. Derating follows the linear curve in Figure 1: P_D = 370 mW × (1 − (T_A − 25)/125).

Does MMSZ5255B-7-F have polarity marking for PCB layout?

Yes-the cathode is marked by a visible band on the SOD123 body. In top view, the band aligns with the cathode terminal; correct orientation is essential to ensure reverse-bias operation and proper voltage clamping behavior.

MMSZ5255B-7-F Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: SOD-123

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 28 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 44 Ohms

Current - Reverse Leakage @ Vr:: 100 nA @ 21 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:: SOD-123

MMSZ5255B-7-F FAQ

1.How can I place an order for MMSZ5255B-7-F through Aetrix?

Please submit a Request for Quotation (RFQ) for MMSZ5255B-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 MMSZ5255B-7-F reliable?

The price and inventory of MMSZ5255B-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 MMSZ5255B-7-F is usually 5 days.

3.What payment methods are accepted for MMSZ5255B-7-F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ5255B-7-F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMSZ5255B-7-F?

MMSZ5255B-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMSZ5255B-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 MMSZ5255B-7-F?

For technical support, including MMSZ5255B-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ5255B-7-F requirements.

6.How does Aetrix verify that MMSZ5255B-7-F is sourced from the original manufacturer or authorized distributors?

All MMSZ5255B-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 MMSZ5255B-7-F meets industry standards.

7.What is the process for return or replacement of MMSZ5255B-7-F?

All MMSZ5255B-7-F units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ5255B-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 MMSZ5255B-7-F part is unused and in its original packaging.

Return procedure for MMSZ5255B-7-F:

1.Submit a request within 90 days.

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

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