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

onsemi SZMMBZ5229BLT1G

Name: SZMMBZ5229BLT1G
Brand: onsemi
SKU: SZMMBZ5229BLT1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SZMMBZ5229BLT1G

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: SZMMBZ5229BLT1G.pdf

Description:: DIODE ZENER 4.3V 225MW SOT23-3

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Product details

Overview

SZMMBZ5229BLT1G from onsemi is a 4.3 V ±5% Zener diode in SOT-23 package, rated for 225 mW power dissipation on FR-5 board, with 22 Ω dynamic impedance at 20 mA test current and 5 μA reverse leakage at 1 V reverse bias. It serves as a precision voltage reference or overvoltage clamp in low-power portable electronics.

For engineers reviewing the SZMMBZ5229BLT1G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance, thermal resistance (556 °C/W), ESD rating (>16 kV HBM), AEC-Q101 qualification, and SOT-23 footprint compatibility with high-density PCB layouts.

Technical Context

This device operates as a two-terminal voltage regulator using avalanche breakdown in silicon PN junction. Its nominal Zener voltage of 4.3 V is specified at 20 mA test current (IZT) with ±5% tolerance, and exhibits a temperature coefficient near zero in this range - critical for stable reference performance across −65°C to +150°C junction temperature.

The SOT-23 package features Pin 1 (Anode), Pin 2 (No Connection), and Pin 3 (Cathode), enabling unidirectional clamping or shunt regulation. With 225 mW power rating on FR-5 board and 300 mW on alumina substrate, it supports compact, thermally constrained designs where space and reliability are prioritized over high-power handling.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	4.3 V nominal, 4.08–4.52 V min–max at I_ZT = 20 mA - defines precise clamping threshold for 3.3 V/5 V rail protection
Power Dissipation (P_D)	225 mW on FR-5 board @ 25°C - sets maximum continuous shunt current to ~52 mA at 4.3 V
Zener Impedance (Z_ZT)	22 Ω max @ I_ZT = 20 mA - ensures minimal voltage deviation under load transients
Reverse Leakage (I_R)	5 μA max @ V_R = 1 V - guarantees low quiescent current in standby mode
ESD Rating	Class 3 (>16 kV) per Human Body Model - enables direct integration into handheld ESD-prone interfaces without external protection
Junction Temp Range	−65°C to +150°C - supports operation in automotive under-hood and industrial environments
AEC-Q101 Qualified	Yes - validated for automotive electronics requiring stress-tested reliability and PPAP documentation

Pinout & Package

SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm, void-free thermosetting plastic case with corrosion-resistant finish. Cathode indicated by polarity band.

Pin/Terminal	Circuit Role	Design Meaning
1	Anode	Connected to lower-potential node (e.g., GND or regulated rail return); current flows into cathode during regulation
2	No Connection	Internally unconnected; must remain floating - no PCB trace or pad required
3	Cathode	Connected to higher-potential node (e.g., supply rail); defines Zener breakdown voltage relative to anode

Key Features

Feature	Design Value
225 mW FR-5 Power Rating	Enables reliable voltage clamping in space-constrained mobile PCBs without heatsinking
ESD Robustness >16 kV HBM	Eliminates need for discrete ESD protection diodes in USB, button, or sensor interface lines
AEC-Q101 Qualification	Validates suitability for automotive infotainment, body control, and ADAS subsystems requiring certified component reliability
Pb-Free, Halogen-Free, RoHS Compliant	Meets global environmental compliance mandates without compromising thermal or electrical performance
Small SOT-23 Footprint	Reduces board area by >60% vs. DO-35, supporting >2× component density on high-pin-count IC power domains

Applications

USB Port Overvoltage Protection	Automotive Cabin Sensor Reference
Use Scenario: Clamping transient surges on USB VBUS line in portable docking stations. IC Role / Device Role / Timing Role: Shunt Zener regulator placed between VBUS and GND to clamp spikes above 4.3 V. Use Value: Prevents damage to downstream USB PHY ICs by limiting excursion to ≤4.52 V with <22 Ω dynamic impedance.	Use Scenario: Providing stable 4.3 V reference for analog sensor signal conditioning in vehicle cabin modules. IC Role / Device Role / Timing Role: Precision voltage reference for ADC biasing and op-amp feedback networks. Use Value: Maintains ±5% accuracy across −40°C to +125°C ambient, meeting AEC-Q100 Grade 2 requirements.
Low-Power IoT Node Voltage Clamp	Industrial PLC Input Protection
Use Scenario: Protecting GPIO and ADC inputs of battery-powered BLE sensors against ESD and coupling noise. IC Role / Device Role / Timing Role: Bidirectional ESD clamp (anode-to-GND, cathode-to-signal) leveraging HBM >16 kV rating. Use Value: Absorbs 15 kV contact discharge without degradation, verified per AEC-Q101 stress testing protocols.	Use Scenario: Safeguarding 24 V digital input channels in programmable logic controllers against field-wiring faults. IC Role / Device Role / Timing Role: Front-end Zener clamp before optocoupler input, limiting voltage to 4.52 V before series resistor. Use Value: Enables robust 24 V channel design with <5 μA leakage at 1 V, minimizing false triggering in noisy factory environments.

USB Port Overvoltage Protection

Automotive Cabin Sensor Reference

Use Scenario: Clamping transient surges on USB VBUS line in portable docking stations.

IC Role / Device Role / Timing Role: Shunt Zener regulator placed between VBUS and GND to clamp spikes above 4.3 V.

Use Value: Prevents damage to downstream USB PHY ICs by limiting excursion to ≤4.52 V with <22 Ω dynamic impedance.

Use Scenario: Providing stable 4.3 V reference for analog sensor signal conditioning in vehicle cabin modules.

IC Role / Device Role / Timing Role: Precision voltage reference for ADC biasing and op-amp feedback networks.

Use Value: Maintains ±5% accuracy across −40°C to +125°C ambient, meeting AEC-Q100 Grade 2 requirements.

Low-Power IoT Node Voltage Clamp

Industrial PLC Input Protection

Use Scenario: Protecting GPIO and ADC inputs of battery-powered BLE sensors against ESD and coupling noise.

IC Role / Device Role / Timing Role: Bidirectional ESD clamp (anode-to-GND, cathode-to-signal) leveraging HBM >16 kV rating.

Use Value: Absorbs 15 kV contact discharge without degradation, verified per AEC-Q101 stress testing protocols.

Use Scenario: Safeguarding 24 V digital input channels in programmable logic controllers against field-wiring faults.

IC Role / Device Role / Timing Role: Front-end Zener clamp before optocoupler input, limiting voltage to 4.52 V before series resistor.

Use Value: Enables robust 24 V channel design with <5 μA leakage at 1 V, minimizing false triggering in noisy factory environments.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84-C4V3LT1G	Same 4.3 V nominal, but 350 mW rating on FR-4 and no AEC-Q101 qualification; Z_ZT = 90 Ω max	Targeted at commercial-grade consumer electronics, not automotive or industrial harsh environments	Select when cost sensitivity outweighs automotive qualification and lower impedance is acceptable
SZBZX84C4V3LT1G	AEC-Q101 qualified like SZMMBZ5229BLT1G, but 4.3 V ±5% with 90 Ω Z_ZT and 100 nA leakage @ 1 V	Offers tighter leakage spec but higher impedance - better for ultra-low-power sleep modes, worse for transient suppression	Prefer for battery-critical applications needing sub-100 nA leakage, accepting reduced surge response fidelity

Compared with BZX84-C4V3LT1G and SZBZX84C4V3LT1G, SZMMBZ5229BLT1G delivers superior dynamic regulation (22 Ω vs. ≥90 Ω) and proven automotive stress resilience, making it optimal for safety-aware or high-transient environments where voltage stability under load is non-negotiable.

Availability

SZMMBZ5229BLT1G is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial sensor nodes, and portable medical devices requiring stable component supply with full AEC-Q101 traceability and RoHS compliance.

Supply support for SZMMBZ5229BLT1G 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

SZMMBZ5229BLT1G belongs to the SZMMBZ52xxBLT1G automotive-qualified Zener series, designed specifically for voltage regulation and ESD protection in space-constrained, high-reliability electronic control units.

FAQ

What is the Zener voltage tolerance of SZMMBZ5229BLT1G?

The SZMMBZ5229BLT1G has a Zener voltage tolerance of ±5% around its nominal 4.3 V rating, meaning the actual measured V_Z falls between 4.08 V and 4.52 V when tested at I_ZT = 20 mA and T_A = 25°C. This tight tolerance ensures predictable clamping behavior in precision reference and protection circuits, and is confirmed in the Electrical Characteristics table on page 3 of the official onsemi datasheet for SZMMBZ5229BLT1G.

Is SZMMBZ5229BLT1G suitable for automotive applications?

Yes, SZMMBZ5229BLT1G is explicitly AEC-Q101 qualified and PPAP capable, with the "SZ" prefix indicating automotive-grade process controls, site-specific change management, and enhanced reliability validation. It operates across −65°C to +150°C junction temperature and passes rigorous stress tests required for engine control, body electronics, and ADAS subsystems - all documented in the onsemi SZMMBZ5229BLT1G datasheet.

What is the thermal resistance of SZMMBZ5229BLT1G on standard PCB?

The junction-to-ambient thermal resistance (R_JA) of SZMMBZ5229BLT1G is 556 °C/W when mounted on an FR-5 board, as specified in the Maximum Ratings table. This value determines how much the junction temperature rises above ambient per milliwatt of dissipated power - critical for derating calculations in enclosed or high-temperature environments where SZMMBZ5229BLT1G may operate near its 225 mW limit.

Does SZMMBZ5229BLT1G have a no-connect pin, and how should it be handled?

Yes, SZMMBZ5229BLT1G has Pin 2 designated as "No Connection" per the mechanical outline (Style 8) and Electrical Characteristics table. This terminal is internally unconnected and must remain electrically floating on the PCB - no trace, pad, or solder mask opening is required. Incorrect routing or grounding of Pin 2 may compromise device reliability or violate the SOT-23 layout guidelines defined in the SZMMBZ5229BLT1G datasheet.

How does the ESD rating of SZMMBZ5229BLT1G compare to standard Zener diodes?

SZMMBZ5229BLT1G achieves Class 3 ESD robustness (>16 kV) per Human Body Model, significantly exceeding typical Zener diodes rated at 8 kV or less. This high immunity allows direct placement on exposed I/O lines (e.g., buttons, sensors, USB) without supplemental TVS devices - a capability verified in onsemi's qualification testing and explicitly stated in the Features section of the SZMMBZ5229BLT1G datasheet.

SZMMBZ5229BLT1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Voltage - Zener (Nom) (Vz):: 4.3 V

Tolerance:: ±5%

Power - Max:: 225 mW

Impedance (Max) (Zzt):: 22 Ohms

Current - Reverse Leakage @ Vr:: 5 µA @ 1 V

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

Operating Temperature:: -65°C ~ 150°C

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3 (TO-236)

SZMMBZ5229BLT1G FAQ

1.How can I place an order for SZMMBZ5229BLT1G through Aetrix?

Please submit a Request for Quotation (RFQ) for SZMMBZ5229BLT1G 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 SZMMBZ5229BLT1G reliable?

The price and inventory of SZMMBZ5229BLT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZMMBZ5229BLT1G is usually 5 days.

3.What payment methods are accepted for SZMMBZ5229BLT1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZMMBZ5229BLT1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SZMMBZ5229BLT1G?

SZMMBZ5229BLT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SZMMBZ5229BLT1G 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 SZMMBZ5229BLT1G?

For technical support, including SZMMBZ5229BLT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZMMBZ5229BLT1G requirements.

6.How does Aetrix verify that SZMMBZ5229BLT1G is sourced from the original manufacturer or authorized distributors?

All SZMMBZ5229BLT1G 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 SZMMBZ5229BLT1G meets industry standards.

7.What is the process for return or replacement of SZMMBZ5229BLT1G?

All SZMMBZ5229BLT1G units undergo pre-shipment inspection (PSI). If there is an issue with SZMMBZ5229BLT1G, 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 SZMMBZ5229BLT1G part is unused and in its original packaging.

Return procedure for SZMMBZ5229BLT1G:

1.Submit a request within 90 days.

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

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