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

Diodes Incorporated MMSZ5251B-7-F

Name: MMSZ5251B-7-F
Brand: Diodes Incorporated
SKU: MMSZ5251B-7-F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMSZ5251B-7-F

Manufacturer:: Diodes Incorporated

Category:: Single Zener Diodes

Package:: SOD-123

Datasheet:: MMSZ5251B-7-F.pdf

Description:: DIODE ZENER 22V 500MW SOD123

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Inventory:18,919

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Product details

Overview

MMSZ5251B-7-F from Diodes Incorporated is a 22 V, 500 mW surface-mount Zener diode in SOD-123 package, rated for 5.6 mA test current with 29 Ω zener impedance at 1 kHz and 0.1 µA reverse leakage at 17 V, widely used for voltage regulation and reference in power supply feedback loops and overvoltage protection circuits.

For engineers reviewing the MMSZ5251B-7-F datasheet, MMSZ5251B-7-F pinout, MMSZ5251B-7-F application, or MMSZ5251B-7-F equivalent, key selection criteria include nominal zener voltage tolerance (±5%), thermal resistance (338 °C/W), cathode-band polarity marking, RoHS-compliant lead-free plating, and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This Zener diode operates in reverse breakdown to maintain stable voltage across its terminals under varying load and temperature conditions. Its 22 V nominal zener voltage exhibits a positive temperature coefficient of approximately +0.06 %/°C, and it delivers regulated output with ≤5% voltage deviation over the 20.9–23.1 V range at I_ZT = 5.6 mA.

The device is optimized for low-power, medium-current regulation in space-constrained PCB layouts. With 370 mW power dissipation at T_A = +25°C and derating to 500 mW at T_L = +75°C, it supports operation within -65°C to +150°C ambient and storage temperature ranges.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	22 V nominal, 20.9–23.1 V range at 5.6 mA - ensures tight regulation for 24 V rail monitoring and feedback sensing.
Power Dissipation (P_D)	370 mW @ T_A = +25°C - defines maximum continuous power in standard PCB layout without heatsinking.
Zener Impedance (Z_ZT)	29 Ω @ 1 kHz, 5.6 mA - determines AC ripple rejection capability in precision reference applications.
Reverse Leakage (I_R)	0.1 µA @ V_R = 17 V - guarantees minimal quiescent current draw in battery-powered voltage monitor circuits.
Thermal Resistance (R_θJA)	338 °C/W - indicates junction-to-ambient heat transfer efficiency on FR-4 with 1-inch copper pad.
Package	SOD-123 - surface-mount footprint (2.65 mm × 1.55 mm × 1.05 mm) compatible with automated pick-and-place assembly.
AEC-Q101 Qualified	Yes - validated for automotive electronics requiring high-reliability stress testing (HTOL, TC, HAST).

Pinout & Package

Package: SOD-123 - molded plastic case with matte tin-plated alloy 42 leadframe, cathode band marking on top surface, moisture sensitivity level 1 per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / Zener cathode reference ground node	Connected to circuit ground or lower-potential node; forms reference return path in shunt regulator topology.
Cathode	Zener breakdown terminal / regulated output node	Connected to input voltage source; maintains stable 22 V relative to anode during reverse bias operation.

Key Features

Feature	Design Value
500 mW power rating at T_L = +75°C	Enables reliable operation in thermally constrained automotive cabin modules and industrial control enclosures.
Totally lead-free & RoHS 2 compliant	Meets EU Directive 2011/65/EU requirements without exemptions, supporting global environmental compliance programs.
Halogen- and antimony-free "Green" compound	Contains <900 ppm Br, <900 ppm Cl, <1000 ppm Sb - satisfies stringent material declarations for Tier-1 automotive OEMs.
Automated assembly compatible	SOD-123 footprint and matte tin finish ensure consistent solder wetting and placement yield in high-speed SMT lines.

Applications

Power Supply Feedback Regulation

Overvoltage Protection Clamp

Use Scenario: Stabilizing feedback voltage in isolated DC-DC converter secondary-side TL431-based regulators.

IC Role / Device Role / Timing Role: Shunt reference element providing precise 22 V threshold to control optocoupler LED current.

Use Value: Maintains ±1.5% output voltage accuracy over line/load/temperature due to tight 20.9–23.1 V tolerance and low Z_ZT.

Use Scenario: Clamping transient surges on 24 V CAN bus power rails in automotive body control modules.

IC Role / Device Role / Timing Role: Fast-acting voltage clamp absorbing ESD and load-dump energy before downstream ICs are damaged.

Use Value: Limits peak voltage to ≤23.1 V with 0.1 µA leakage at 17 V, minimizing standby power loss and false triggering.

Reference Voltage Source

Microcontroller Reset Circuit

Use Scenario: Generating stable 22 V reference for analog-to-digital conversion in industrial sensor signal conditioning.

IC Role / Device Role / Timing Role: Precision voltage reference for ADC reference divider networks requiring low drift and noise.

Use Value: Delivers <0.06 %/°C tempco and 29 Ω dynamic impedance, reducing measurement error in 12-bit+ systems.

Use Scenario: Monitoring 24 V system rail to assert reset on microcontrollers when voltage drops below safe operating level.

IC Role / Device Role / Timing Role: Threshold detector in discrete reset generator circuits using comparator and RC timing.

Use Value: Provides sharp, repeatable 22 V turn-on with cathode-band polarity ensuring unambiguous board-level orientation.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX584C22LT1G	22 V, 300 mW, SOD-323 package, 40 Ω Z_ZT, 0.1 µA I_R @ 17 V	Lower power rating and smaller footprint - suitable only for sub-100 mW reference use, not for clamping.	Select when board space is critical and thermal load is low; verify derating curves for ambient >60°C.
MMBZ5251BS-7-F	22 V, 300 mW, SOT-23 package, 35 Ω Z_ZT, 0.1 µA I_R @ 17 V, same AEC-Q101 qualification	Higher thermal resistance (400 °C/W), requires larger copper area for equivalent power handling.	Prefer for designs already using SOT-23 footprints and needing identical automotive qualification but accepting higher Z_ZT.

Compared with BZX584C22LT1G and MMBZ5251BS-7-F, MMSZ5251B-7-F offers superior power handling (370 mW vs. 300 mW) and lower zener impedance (29 Ω vs. 35–40 Ω), making it better suited for active clamping and higher-current reference roles in automotive and industrial environments.

Availability

MMSZ5251B-7-F is available at Aetrix Electronics and suitable for automotive power management, industrial sensor reference design, and telecom surge protection requiring stable component supply and full traceability.

Supply support for MMSZ5251B-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.

MMSZ5251B-7-F belongs to the MMSZ52xxB series of AEC-Q101-qualified Zener diodes designed specifically for voltage regulation and protection in harsh-environment automotive electronics and industrial control systems.

FAQ

What is the maximum continuous reverse voltage that MMSZ5251B-7-F can withstand without breakdown?

The MMSZ5251B-7-F has a nominal zener voltage of 22 V with a guaranteed range of 20.9–23.1 V at 5.6 mA test current. It begins controlled reverse breakdown at ≥20.9 V and maintains regulation up to its power limit. Applying >23.1 V continuously without current limiting risks thermal runaway and permanent damage.

Is MMSZ5251B-7-F suitable for use in automotive engine control units (ECUs)?

Yes - it is AEC-Q101 qualified and manufactured with halogen- and antimony-free green molding compound. Its -65°C to +150°C operating temperature range, 338 °C/W thermal resistance, and robust SOD-123 package make it appropriate for under-hood ECU voltage monitoring and feedback circuits.

How does the SOD-123 package affect soldering process compatibility?

The SOD-123 package uses matte tin-plated alloy 42 leads and conforms to MIL-STD-202 Method 208 solderability standards. Its 2.65 mm × 1.55 mm footprint and 1.05 mm height support standard reflow profiles (peak 260°C, 60 sec max), with no special stencil or thermal profiling required for high-yield SMT assembly.

Does MMSZ5251B-7-F have a specified capacitance value relevant for high-frequency applications?

No capacitance specification is provided in the DS18010 datasheet for MMSZ5251B-7-F. Figure 4 shows typical total capacitance decreasing with increasing zener voltage - for 22 V devices, estimated C_T is ~15 pF based on interpolation of adjacent values (e.g., 18 V ≈ 18 pF, 27 V ≈ 10 pF), but this is not characterized or guaranteed.

MMSZ5251B-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):: 22 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 29 Ohms

Current - Reverse Leakage @ Vr:: 100 nA @ 17 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

MMSZ5251B-7-F FAQ

1.How can I place an order for MMSZ5251B-7-F through Aetrix?

Please submit a Request for Quotation (RFQ) for MMSZ5251B-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 MMSZ5251B-7-F reliable?

The price and inventory of MMSZ5251B-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 MMSZ5251B-7-F is usually 5 days.

3.What payment methods are accepted for MMSZ5251B-7-F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ5251B-7-F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMSZ5251B-7-F?

MMSZ5251B-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMSZ5251B-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 MMSZ5251B-7-F?

For technical support, including MMSZ5251B-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ5251B-7-F requirements.

6.How does Aetrix verify that MMSZ5251B-7-F is sourced from the original manufacturer or authorized distributors?

All MMSZ5251B-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 MMSZ5251B-7-F meets industry standards.

7.What is the process for return or replacement of MMSZ5251B-7-F?

All MMSZ5251B-7-F units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ5251B-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 MMSZ5251B-7-F part is unused and in its original packaging.

Return procedure for MMSZ5251B-7-F:

1.Submit a request within 90 days.

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

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