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

onsemi MMSZ5242BT3G

Name: MMSZ5242BT3G
Brand: onsemi
SKU: MMSZ5242BT3G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMSZ5242BT3G

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: SOD-123

Datasheet:: MMSZ5242BT3G.pdf

Description:: DIODE ZENER 12V 500MW SOD123

Quantity:: RFQ Add To RFQ list

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Inventory:29,801

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Product details

Overview

MMSZ5242BT3G from onsemi is a 12 V ±5% Zener diode in SOD−123 package, rated for 500 mW power dissipation at TL = 75°C with 30 Ω dynamic impedance at 20 mA test current, used for voltage regulation and reference in low-power analog circuits, power supply feedback loops, and overvoltage protection.

For engineers reviewing the MMSZ5242BT3G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance (±5%), thermal equilibrium specification, cathode-anode polarity marking, and compatibility with automated SMT assembly on FR-4/FR-5 boards.

Technical Context

This device operates as a two-terminal voltage reference diode, conducting in reverse breakdown at nominal 12 V with specified Zener impedance of 30 Ω at IZT = 20 mA and 600 Ω at IZK = 0.25 mA. Its junction temperature range spans −55°C to +150°C, and it exhibits a typical temperature coefficient near +0.085 %/°C for 12 V devices per Figure 1.

The SOD−123 package features a defined cathode band, Pb-free construction, UL 94 V−0 flammability rating, and maximum soldering temperature of 260°C for 10 seconds. Thermal resistance is 340°C/W (junction-to-ambient) and 150°C/W (junction-to-lead), enabling stable operation under controlled board layout conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	11.4 V min / 12.6 V max @ I_ZT = 20 mA - defines regulated output voltage window under standard test conditions
Power Dissipation (P_D)	500 mW on FR-5 board @ T_L = 75°C - sets maximum continuous power handling before thermal derating applies
Zener Impedance (Z_ZT)	30 Ω @ I_ZT = 20 mA - indicates voltage regulation stability under nominal operating current
Reverse Leakage (I_R)	1 μA @ V_R = 9.1 V - quantifies off-state conduction loss below breakdown threshold
Forward Voltage (V_F)	≤ 0.95 V @ I_F = 10 mA - confirms low-loss forward conduction when used bidirectionally or in clamp configurations
Package	SOD−123 (Case 425) - surface-mount 2-lead plastic package measuring 1.60 × 2.69 × 1.16 mm for high-density PCB layouts
ESD Rating	Class 3 (>16 kV HBM) - ensures robustness against electrostatic discharge during handling and assembly

Pinout & Package

SOD−123 package with cathode indicated by polarity band; terminals are unidirectional, non-polarized in function but polarity-critical for correct circuit connection.

Pin/Terminal	Circuit Role	Design Meaning
1 (Banded End)	Cathode	Connected to higher potential side in reverse-bias regulation; must be oriented toward supply rail in shunt configuration
2 (Non-banded End)	Anode	Connected to lower potential side (e.g., ground or feedback node); completes current path during Zener conduction

Key Features

Feature	Design Value
500 mW Power Rating	Enables use in medium-current regulation without external heat sinking on standard PCBs
±5% Zener Tolerance	Supports cost-sensitive applications where tight voltage accuracy is not required
Thermal Equilibrium Spec	Ensures V_Z values measured under stabilized thermal conditions for repeatable design validation
Pb-Free & AEC-Q101 Capable	Meets automotive qualification requirements and RoHS compliance for industrial and automotive end equipment
Optimized SMT Package	SOD−123 footprint supports high-speed pick-and-place assembly and reflow compatibility

Applications

Power Supply Feedback	Overvoltage Clamp
Use Scenario: Used in secondary-side feedback loop of isolated DC-DC converters to regulate output voltage via optocoupler interface. IC Role / Device Role / Timing Role: Zener reference diode providing precise 12 V threshold for TL431 or similar shunt regulator control. Use Value: Maintains ±5% output regulation across line/load variations without requiring active compensation components.	Use Scenario: Placed across sensitive IC inputs to limit transient overvoltage from ESD or inductive switching events. IC Role / Device Role / Timing Role: Passive clamping element diverting surge current above 12.6 V to ground before damage occurs. Use Value: Limits peak voltage to ≤12.6 V while sustaining <1 μA leakage at 9.1 V, minimizing standby power impact.
Reference Voltage Source	Signal Level Shifting
Use Scenario: Provides stable 12 V reference for ADC biasing, sensor excitation, or comparator thresholds in battery-powered instrumentation. IC Role / Device Role / Timing Role: Two-terminal passive voltage reference replacing more complex IC references where moderate accuracy suffices. Use Value: Delivers 12 V ±5% with 30 Ω dynamic impedance, enabling stable biasing even with modest load current changes.	Use Scenario: Shifts logic-level signals between 3.3 V and 5 V domains using series resistor and Zener clamp topology. IC Role / Device Role / Timing Role: Clamping diode establishing upper voltage rail at 12 V for level translation with minimal component count. Use Value: Enables bidirectional signal translation with fast response (<1 ns rise time implied by low capacitance), leveraging low forward voltage drop.

Power Supply Feedback

Overvoltage Clamp

Use Scenario: Used in secondary-side feedback loop of isolated DC-DC converters to regulate output voltage via optocoupler interface.

IC Role / Device Role / Timing Role: Zener reference diode providing precise 12 V threshold for TL431 or similar shunt regulator control.

Use Value: Maintains ±5% output regulation across line/load variations without requiring active compensation components.

Use Scenario: Placed across sensitive IC inputs to limit transient overvoltage from ESD or inductive switching events.

IC Role / Device Role / Timing Role: Passive clamping element diverting surge current above 12.6 V to ground before damage occurs.

Use Value: Limits peak voltage to ≤12.6 V while sustaining <1 μA leakage at 9.1 V, minimizing standby power impact.

Reference Voltage Source

Signal Level Shifting

Use Scenario: Provides stable 12 V reference for ADC biasing, sensor excitation, or comparator thresholds in battery-powered instrumentation.

IC Role / Device Role / Timing Role: Two-terminal passive voltage reference replacing more complex IC references where moderate accuracy suffices.

Use Value: Delivers 12 V ±5% with 30 Ω dynamic impedance, enabling stable biasing even with modest load current changes.

Use Scenario: Shifts logic-level signals between 3.3 V and 5 V domains using series resistor and Zener clamp topology.

IC Role / Device Role / Timing Role: Clamping diode establishing upper voltage rail at 12 V for level translation with minimal component count.

Use Value: Enables bidirectional signal translation with fast response (<1 ns rise time implied by low capacitance), leveraging low forward voltage drop.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX584-C12	Same 12 V ±5%, SOD-323 package (smaller: 1.3 × 0.85 × 0.7 mm), 300 mW rating	Lower power handling limits use in >10 mA regulation; better suited for space-constrained, low-current nodes	Select BZX584-C12 only if board area is critical and power demand stays below 300 mW
1N4742A	Same 12 V ±5%, DO-41 through-hole package, 1 W rating, higher thermal mass	Requires manual or wave soldering; unsuitable for fully SMT production but offers superior surge capability	Choose 1N4742A for prototyping, repair, or high-surge environments where SMT is not mandatory

Compared with MMSZ5242BT3G, BZX584-C12 trades power margin for footprint reduction, while 1N4742A sacrifices automation compatibility for higher surge resilience and thermal inertia-neither is pin-compatible due to differing packages.

Availability

MMSZ5242BT3G is available at Aetrix Electronics and suitable for power supply feedback, overvoltage protection, reference voltage generation, and signal level shifting requiring stable component supply and full traceability.

Supply support for MMSZ5242BT3G 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 (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MMSZ52xxxT1G Series targets general-purpose, medium-current Zener regulation in compact SMT formats, designed specifically for cost-sensitive, high-volume applications needing reliable voltage reference without active circuitry.

FAQ

What is the Zener voltage tolerance for MMSZ5242BT3G?

The MMSZ5242BT3G has a Zener voltage tolerance of ±5% at I_ZT = 20 mA, with a nominal value of 12 V, resulting in a guaranteed range of 11.4 V to 12.6 V. This tolerance is specified under thermal equilibrium conditions at T_L = 30°C ±1°C, as confirmed in the Electrical Characteristics table on page 3 of the onsemi datasheet. The "B" suffix in MMSZ5242BT3G explicitly denotes this 5% tolerance grade.

Is MMSZ5242BT3G suitable for automotive applications?

Yes, MMSZ5242BT3G is suitable for automotive applications because it is AEC-Q101 qualified and PPAP capable when ordered with the SZ prefix (e.g., SZMMSZ5242BT3G). Even in standard MMSZ5242BT3G form, it meets the same reliability and process controls required for automotive use, including Class 3 HBM ESD rating (>16 kV) and Pb-free construction compliant with RoHS directives.

What is the maximum power dissipation of MMSZ5242BT3G on an FR-5 board?

The maximum power dissipation of MMSZ5242BT3G on an FR-5 board is 500 mW at lead temperature (T_L) = 75°C, with linear derating of 6.7 mW/°C above that temperature. This rating assumes use of the minimum recommended footprint on FR-5 material, as defined in Note 1 of the Maximum Ratings table. Exceeding this limit risks thermal runaway and permanent degradation of the MMSZ5242BT3G device.

Does MMSZ5242BT3G have a specified forward voltage?

Yes, MMSZ5242BT3G has a specified forward voltage of ≤0.95 V at I_F = 10 mA, as stated in the Electrical Characteristics table. This parameter confirms predictable low-loss conduction in forward bias, supporting dual-use cases such as reverse-bias regulation and forward-bias clamping or logic-level interfacing. The value is measured at T_A = 25°C and aligns with silicon diode behavior.

How is polarity marked on the MMSZ5242BT3G SOD−123 package?

Polarity on the MMSZ5242BT3G SOD−123 package is marked by a cathode band at terminal 1, located at the banded end of the device body. The non-banded end is the anode (terminal 2). This marking is consistent across the MMSZ52xxxT1G Series and is visible under standard optical inspection. Correct orientation is essential for proper reverse-bias operation in regulation or clamping circuits using MMSZ5242BT3G.

MMSZ5242BT3G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SOD-123

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 12 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 30 Ohms

Current - Reverse Leakage @ Vr:: 1 µA @ 9.1 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:: SOD-123

MMSZ5242BT3G FAQ

1.How can I place an order for MMSZ5242BT3G through Aetrix?

Please submit a Request for Quotation (RFQ) for MMSZ5242BT3G 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 MMSZ5242BT3G reliable?

The price and inventory of MMSZ5242BT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMSZ5242BT3G is usually 5 days.

3.What payment methods are accepted for MMSZ5242BT3G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ5242BT3G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMSZ5242BT3G?

MMSZ5242BT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMSZ5242BT3G 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 MMSZ5242BT3G?

For technical support, including MMSZ5242BT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ5242BT3G requirements.

6.How does Aetrix verify that MMSZ5242BT3G is sourced from the original manufacturer or authorized distributors?

All MMSZ5242BT3G 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 MMSZ5242BT3G meets industry standards.

7.What is the process for return or replacement of MMSZ5242BT3G?

All MMSZ5242BT3G units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ5242BT3G, 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 MMSZ5242BT3G part is unused and in its original packaging.

Return procedure for MMSZ5242BT3G:

1.Submit a request within 90 days.

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

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