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

onsemi MMSZ4678T1

Name: MMSZ4678T1
Brand: onsemi
SKU: MMSZ4678T1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMSZ4678T1

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: SOD-123

Datasheet:: MMSZ4678T1.pdf

Description:: DIODE ZENER 1.8V 500MW SOD123

Quantity:: RFQ Add To RFQ list

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Inventory:6,536

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Product details

Overview

MMSZ4678T1 from onsemi is a 1.8 V, 500 mW surface-mount Zener diode in SOD−123 package, designed for precision voltage regulation and reference in low-power analog circuits. It delivers nominal Zener voltage of 1.8 V at 50 µA test current, with ±5% tolerance (1.71–1.89 V), low leakage (<7.5 µA at 1 V reverse bias), and ESD robustness (>16 kV HBM).

For engineers reviewing the MMSZ4678T1 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy at low I_ZT, thermal stability in compact layouts, compatibility with automated SMT assembly, and compliance with automotive-grade reliability requirements (AEC−Q101 optional via SZ prefix).

Technical Context

This device operates as a two-terminal voltage reference by maintaining a stable reverse breakdown voltage across its cathode-anode junction under controlled Zener current. Its low 50 µA test current enables regulation in ultra-low-power systems, while the 1.8 V nominal voltage supports modern low-voltage logic and sensor biasing.

The SOD−123 package provides a thermally efficient path (R_JL = 150 °C/W) and mechanical robustness for high-density PCBs. With −55°C to +150°C operating range and Class 3 ESD rating, it supports industrial and automotive environments where ambient temperature cycling and electrostatic stress are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	1.8 V nominal, 1.71–1.89 V min/max at I_ZT = 50 µA - ensures tight regulation for 1.8 V rail monitoring or ADC reference scaling.
Power Rating	500 mW on FR-5 board at T_L = 75°C - supports continuous operation in thermally constrained space-limited designs.
Zener Test Current	50 µA - enables stable regulation in micro-power applications such as battery-backed real-time clocks or IoT sensor nodes.
Reverse Leakage	<7.5 µA at V_R = 1 V - minimizes quiescent current draw in always-on standby circuits.
ESD Rating	>16 kV per Human Body Model - protects against handling-induced damage during manual assembly or field service.
Operating Temp	−55°C to +150°C - qualified for under-hood automotive, industrial control, and outdoor equipment deployments.

Pinout & Package

SOD−123 surface-mount plastic package (1.60 × 2.69 × 1.16 mm), void-free thermosetting case with corrosion-resistant finish; cathode indicated by polarity band; UL 94 V−0 flammability rating; maximum solder temperature 260°C for 10 seconds.

Pin/Terminal	Circuit Role	Design Meaning
1 (Cathode)	Zener breakdown terminal	Connected to regulated voltage node; polarity band identifies this terminal for correct orientation in series-shunt regulation topologies.
2 (Anode)	Reference ground return	Typically tied to system ground or common reference plane; completes current path during reverse-bias conduction.

Key Features

Feature	Design Value
Low I_ZT operation	Stable 1.8 V regulation at only 50 µA - eliminates need for external current sources in ultra-low-power sensing.
Pb-Free & RoHS	Compliant with environmental directives and lead-free reflow profiles - supports global manufacturing and end-of-life compliance.
Automated assembly optimized	Standardized SOD−123 footprint and marking - enables high-yield pick-and-place and AOI inspection without custom tooling.
AEC−Q101 capability	Available in SZ-prefix variant (SZMMSZ4678T1G) - meets automotive qualification for powertrain and body electronics.

Applications

Low-Voltage Sensor Biasing	Microcontroller Reset Reference
Use Scenario: Providing stable 1.8 V bias to analog front-end of MEMS accelerometers or Hall-effect sensors in portable medical devices. IC Role / Device Role / Timing Role: Precision voltage reference source ensuring consistent sensor output scaling independent of supply variation. Use Value: Enables <±1% measurement repeatability over temperature and battery discharge cycles due to tight V_Z tolerance and low TC near 1.8 V.	Use Scenario: Generating reset threshold for 1.8 V core logic in ARM Cortex-M0+ microcontrollers used in smart home hubs. IC Role / Device Role / Timing Role: Zener-based reset comparator input that triggers POR when V_DD drops below 1.71 V. Use Value: Guarantees deterministic reset assertion without external ICs, reducing BOM count and PCB area in cost-sensitive edge nodes.
USB-C Power Negotiation Reference	Industrial PLC Analog Input Protection
Use Scenario: Supplying reference voltage for CC line voltage detection circuitry in USB-C sink controllers operating from 3.3 V rails. IC Role / Device Role / Timing Role: Stable 1.8 V clamp defining logic-high threshold for USB PD communication signaling. Use Value: Maintains USB-C enumeration reliability across wide ambient temperatures due to specified TC behavior and low leakage.	Use Scenario: Clamping transient overvoltage on 4–20 mA loop inputs in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Low-energy Zener shunt protecting op-amp input stages from ESD and surge events up to 16 kV HBM. Use Value: Prevents field failures caused by electrostatic discharge in factory-floor environments without adding TVS latency or capacitance.

Low-Voltage Sensor Biasing

Microcontroller Reset Reference

Use Scenario: Providing stable 1.8 V bias to analog front-end of MEMS accelerometers or Hall-effect sensors in portable medical devices.

IC Role / Device Role / Timing Role: Precision voltage reference source ensuring consistent sensor output scaling independent of supply variation.

Use Value: Enables <±1% measurement repeatability over temperature and battery discharge cycles due to tight V_Z tolerance and low TC near 1.8 V.

Use Scenario: Generating reset threshold for 1.8 V core logic in ARM Cortex-M0+ microcontrollers used in smart home hubs.

IC Role / Device Role / Timing Role: Zener-based reset comparator input that triggers POR when V_DD drops below 1.71 V.

Use Value: Guarantees deterministic reset assertion without external ICs, reducing BOM count and PCB area in cost-sensitive edge nodes.

USB-C Power Negotiation Reference

Industrial PLC Analog Input Protection

Use Scenario: Supplying reference voltage for CC line voltage detection circuitry in USB-C sink controllers operating from 3.3 V rails.

IC Role / Device Role / Timing Role: Stable 1.8 V clamp defining logic-high threshold for USB PD communication signaling.

Use Value: Maintains USB-C enumeration reliability across wide ambient temperatures due to specified TC behavior and low leakage.

Use Scenario: Clamping transient overvoltage on 4–20 mA loop inputs in DIN-rail mounted programmable logic controllers.

IC Role / Device Role / Timing Role: Low-energy Zener shunt protecting op-amp input stages from ESD and surge events up to 16 kV HBM.

Use Value: Prevents field failures caused by electrostatic discharge in factory-floor environments without adding TVS latency or capacitance.

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-C1V8	Same 1.8 V nominal, but rated at 300 mW and uses SOT-23 package; higher dynamic impedance (Z_ZT ≈ 100 Ω vs. ~30 Ω for MMSZ4678T1).	Less suitable for precision references requiring low noise and tight regulation at low current; better for general-purpose clamping.	Select BZX84-C1V8 only if SOT-23 footprint is required and power dissipation remains below 300 mW.
MMBZ5221BS	1.8 V Zener in SOT-23 package; rated 225 mW; specified leakage <5 µA at 1 V, but no AEC−Q101 option available.	Lacks automotive qualification and thermal derating data for high-reliability deployments; limited to commercial-grade applications.	Choose MMBZ5221BS only for non-automotive, cost-driven consumer designs where qualification traceability is not required.

Compared with BZX84-C1V8 and MMBZ5221BS, the MMSZ4678T1 offers superior power handling (500 mW), lower Zener impedance, and direct AEC−Q101 support via SZ variant - making it preferred for industrial and automotive voltage reference roles demanding long-term stability and thermal resilience.

Availability

MMSZ4678T1 is available at Aetrix Electronics and suitable for low-power voltage reference, sensor biasing, and microcontroller reset circuitry requiring stable component supply across automotive, industrial automation, and portable electronics programs.

Supply support for MMSZ4678T1 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 (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The MMSZ4xxxT1G series was developed to deliver high-reliability, low-power Zener regulation in miniature surface-mount packages - specifically targeting space-constrained, thermally demanding applications where precision and manufacturability are critical.

FAQ

What is the exact Zener voltage tolerance of the MMSZ4678T1 at 25°C?

The MMSZ4678T1 has a nominal Zener voltage of 1.8 V with a guaranteed tolerance of ±5% at I_ZT = 50 µA and T_A = 25°C, meaning the actual measured V_Z falls between 1.71 V and 1.89 V. This specification is verified per onsemi's Electrical Characteristics table on page 3 of the official datasheet.

Does the MMSZ4678T1 support automotive applications?

The standard MMSZ4678T1 is not automotive-qualified, but its SZ-prefixed variant - SZMMSZ4678T1G - is AEC−Q101 qualified and PPAP capable. The MMSZ4678T1 itself shares identical electrical and thermal specs, enabling drop-in qualification upgrades when automotive compliance is required.

What is the maximum reverse leakage current for the MMSZ4678T1 at 1 V bias?

The MMSZ4678T1 exhibits a maximum reverse leakage current of 7.5 µA when biased at V_R = 1 V and T_A = 25°C, as specified in the Electrical Characteristics table. This low leakage supports energy-sensitive applications like battery-powered sensor nodes where standby current must remain sub-10 µA.

Can the MMSZ4678T1 be used in place of a 1.8 V voltage reference IC?

The MMSZ4678T1 serves as a discrete Zener reference, not a buffered IC reference. While it provides 1.8 V regulation, it lacks active error correction, low output impedance, or temperature compensation found in IC references. Use the MMSZ4678T1 only where load current is ≤50 µA and temperature drift within ±5 mV/°C is acceptable.

What is the thermal resistance from junction to lead (R_JL) for the MMSZ4678T1?

The MMSZ4678T1 has a specified junction-to-lead thermal resistance (R_JL) of 150 °C/W, measured per infrared scan method. This value enables accurate thermal modeling when mounting on copper pads or thermal vias, especially important for sustained 500 mW operation in compact SOD−123 layouts.

MMSZ4678T1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SOD-123

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 1.8 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: -

Current - Reverse Leakage @ Vr:: 7.5 µA @ 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

MMSZ4678T1 FAQ

1.How can I place an order for MMSZ4678T1 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMSZ4678T1 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 MMSZ4678T1 reliable?

The price and inventory of MMSZ4678T1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMSZ4678T1 is usually 5 days.

3.What payment methods are accepted for MMSZ4678T1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ4678T1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMSZ4678T1?

MMSZ4678T1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMSZ4678T1 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 MMSZ4678T1?

For technical support, including MMSZ4678T1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ4678T1 requirements.

6.How does Aetrix verify that MMSZ4678T1 is sourced from the original manufacturer or authorized distributors?

All MMSZ4678T1 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 MMSZ4678T1 meets industry standards.

7.What is the process for return or replacement of MMSZ4678T1?

All MMSZ4678T1 units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ4678T1, 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 MMSZ4678T1 part is unused and in its original packaging.

Return procedure for MMSZ4678T1:

1.Submit a request within 90 days.

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

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