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

onsemi SZBZX84C3V9ET1G

Name: SZBZX84C3V9ET1G
Brand: onsemi
SKU: SZBZX84C3V9ET1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SZBZX84C3V9ET1G

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: SZBZX84C3V9ET1G.pdf

Description:: DIODE ZENER 3.9V 225MW SOT23-3

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Product details

Overview

SZBZX84C3V9ET1G from onsemi is a 3.9 V ±0.2 V Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C on FR-5 board, with 90 Ω dynamic impedance at 5 mA test current and −2.5 mV/°C temperature coefficient - used for precision voltage reference and overvoltage protection in portable power rails.

For engineers reviewing the SZBZX84C3V9ET1G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance (±0.2 V), low leakage (<3.0 µA at 3.0 V), AEC-Q101 qualification, Pb-free RoHS compliance, and SOT-23 footprint compatibility with high-density PCB layouts.

Technical Context

This device operates as a two-terminal voltage reference diode with cathode-anode polarity, designed for reverse-biased regulation. Its Zener breakdown is specified at three test currents (1 mA, 5 mA, 20 mA), enabling stable clamping across varying load conditions.

The −2.5 mV/°C temperature coefficient ensures minimal drift over −65°C to +150°C junction range, while 450 pF capacitance at 0 V bias supports low-frequency filtering roles. ESD robustness exceeds 16 kV HBM, meeting stringent requirements for handheld and automotive electronics.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	3.7–4.1 V at 5 mA - tight 5.1% tolerance enables accurate 3.3 V rail clamping without external trimming.
Power Dissipation	250 mW on FR-5 board - supports continuous regulation in space-constrained portable designs.
Zener Impedance (Z_ZT)	90 Ω max at 5 mA - maintains stable output under moderate current transients.
Reverse Leakage Current	<3.0 µA at 3.0 V - minimizes quiescent power loss in battery-powered standby circuits.
Temperature Coefficient	−2.5 mV/°C - negative drift compensates for typical IC supply voltage rise with temperature.
Capacitance	450 pF at 0 V, 1 MHz - suitable for low-speed signal conditioning but not RF bypass.
ESD Rating	Class 3 (>16 kV HBM) - withstands handling and system-level ESD events without parameter shift.

Pinout & Package

SOT-23 (TO-236) package: 2.90 mm × 1.30 mm × 1.00 mm body, void-free thermosetting plastic case, corrosion-resistant finish, UL 94 V-0 flammability rating, cathode indicated by band.

Pin/Terminal	Circuit Role	Design Meaning
1 (Anode)	Forward conduction terminal / Zener cathode reference node	Connected to lower-potential side of regulated node; defines polarity for correct reverse-bias operation.
2 (No Connection)	Internal isolation / unused leadframe stub	Electrically isolated - must remain unconnected to avoid parasitic coupling or thermal path disruption.
3 (Cathode)	Zener breakdown terminal / regulation reference point	Connected to higher-potential side (e.g., V_IN or rail); carries full Zener current during clamping.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive-grade reliability including temperature cycling, HTOL, and ESD stress - suitable for under-hood and infotainment power management.
Pb-free and RoHS compliant	Meets global environmental regulations without compromising solderability or thermal performance up to 260°C for 10 s.
Optimized for automated assembly	Standard SOT-23 footprint and marking (BA6) enable high-yield pick-and-place and AOI inspection in volume production.
High-density packaging	Small 2.90 × 1.30 mm outline allows placement adjacent to ICs on crowded mobile PCBs without thermal interference.
Peak pulse power handling	225 W capability (8 × 20 µs waveform) provides transient overvoltage suppression beyond steady-state ratings.

Applications

USB Power Input Protection	Microcontroller I/O Clamp
Use Scenario: Clamping 5 V USB input to safe levels before LDO regulator input in portable medical devices. IC Role / Device Role / Timing Role: Zener diode acting as shunt overvoltage protector, diverting surge current when input exceeds 4.1 V. Use Value: Prevents LDO damage from hot-plug transients while maintaining <3.0 µA leakage to preserve battery life in sleep mode.	Use Scenario: Protecting 3.3 V GPIO pins of an ARM Cortex-M4 MCU against ESD and bus contention. IC Role / Device Role / Timing Role: Bidirectional clamp (anode grounded, cathode to I/O) limiting voltage swing to ±0.7 V forward / +4.1 V reverse. Use Value: Leverages 16 kV HBM rating and fast response to suppress sub-100 ns ESD pulses without signal distortion.
Automotive Sensor Reference	Low-Power Wearable Battery Monitor
Use Scenario: Providing stable 3.9 V reference for analog front-end of tire pressure sensor module operating at −40°C to +125°C. IC Role / Device Role / Timing Role: Precision voltage reference with −2.5 mV/°C TC compensating for sensor IC drift. Use Value: Maintains ±1.5% reference accuracy across full automotive temperature range without calibration.	Use Scenario: Monitoring Li-ion cell voltage in fitness tracker using resistive divider into ADC, with Zener clamping divider top node. IC Role / Device Role / Timing Role: Overvoltage limiter preventing ADC saturation during charging peaks up to 4.35 V. Use Value: 90 Ω Z_ZT ensures clamp voltage stays within 4.1 V even at 5 mA transient, avoiding ADC clipping.

USB Power Input Protection

Microcontroller I/O Clamp

Use Scenario: Clamping 5 V USB input to safe levels before LDO regulator input in portable medical devices.

IC Role / Device Role / Timing Role: Zener diode acting as shunt overvoltage protector, diverting surge current when input exceeds 4.1 V.

Use Value: Prevents LDO damage from hot-plug transients while maintaining <3.0 µA leakage to preserve battery life in sleep mode.

Use Scenario: Protecting 3.3 V GPIO pins of an ARM Cortex-M4 MCU against ESD and bus contention.

IC Role / Device Role / Timing Role: Bidirectional clamp (anode grounded, cathode to I/O) limiting voltage swing to ±0.7 V forward / +4.1 V reverse.

Use Value: Leverages 16 kV HBM rating and fast response to suppress sub-100 ns ESD pulses without signal distortion.

Automotive Sensor Reference

Low-Power Wearable Battery Monitor

Use Scenario: Providing stable 3.9 V reference for analog front-end of tire pressure sensor module operating at −40°C to +125°C.

IC Role / Device Role / Timing Role: Precision voltage reference with −2.5 mV/°C TC compensating for sensor IC drift.

Use Value: Maintains ±1.5% reference accuracy across full automotive temperature range without calibration.

Use Scenario: Monitoring Li-ion cell voltage in fitness tracker using resistive divider into ADC, with Zener clamping divider top node.

IC Role / Device Role / Timing Role: Overvoltage limiter preventing ADC saturation during charging peaks up to 4.35 V.

Use Value: 90 Ω Z_ZT ensures clamp voltage stays within 4.1 V even at 5 mA transient, avoiding ADC clipping.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84C3V9ET1G	Non-automotive grade; no AEC-Q101 qualification; same electrical specs and SOT-23 package.	Approved for consumer/portable use only; not validated for automotive temperature cycling or PPAP.	Select when cost sensitivity outweighs automotive qualification requirements and supply chain traceability is not mandated.
MMSZ4685T1G	Same 3.9 V nominal Zener, but 350 mW rating on FR-4, 50 Ω Z_ZT, −1.5 mV/°C TC, and no AEC-Q101 certification.	Better power handling and lower impedance, but wider voltage tolerance (3.7–4.1 V → 3.7–4.3 V) and reduced thermal stability.	Prefer for higher-current clamping where tighter TC is less critical and board thermal mass supports 350 mW derating.

Compared with SZBZX84C3V9ET1G, BZX84C3V9ET1G lacks automotive qualification but matches all electrical parameters, while MMSZ4685T1G trades AEC-Q101 compliance for higher power and lower impedance at the expense of temperature stability and voltage tolerance.

Availability

SZBZX84C3V9ET1G is available at Aetrix Electronics and suitable for USB power protection, microcontroller I/O clamping, and automotive sensor reference applications requiring stable component supply, long-term lifecycle support, and AEC-Q101-compliant sourcing.

Supply support for SZBZX84C3V9ET1G 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 silicon solutions for automotive, industrial, cloud, medical, and IoT applications, with emphasis on reliability and sustainability.

SZBZX84C3V9ET1G belongs to the BZX84CxxxET1G/SZBZX84CxxxET1G Zener regulator family, engineered for compact, high-reliability voltage reference and overvoltage protection in space- and power-constrained systems.

FAQ

What is the Zener voltage tolerance of SZBZX84C3V9ET1G at 5 mA test current?

The SZBZX84C3V9ET1G has a Zener voltage range of 3.7 V to 4.1 V at 5 mA (IZT), corresponding to a ±0.2 V absolute tolerance or ±5.1% relative tolerance around the nominal 3.9 V rating. This specification is verified per onsemi's August 2024 Rev. 11 datasheet under TA = 25°C conditions, and applies directly to the SZBZX84C3V9ET1G part number.

Is SZBZX84C3V9ET1G qualified for automotive applications?

Yes, SZBZX84C3V9ET1G is AEC-Q101 qualified and PPAP capable, with validation across temperature cycling, high-temperature operating life, and ESD stress tests required for automotive electronics. The "SZ" prefix explicitly denotes automotive and other applications requiring unique site and control change requirements, distinguishing it from the standard BZX84C3V9ET1G variant.

What is the maximum reverse leakage current for SZBZX84C3V9ET1G at 3.0 V?

The maximum reverse leakage current for SZBZX84C3V9ET1G is 3.0 µA at VR = 3.0 V and TA = 25°C, as specified in the Electrical Characteristics table on page 2 of the onsemi datasheet. This value ensures minimal standby power draw in battery-critical applications such as wearables and remote sensors.

Does SZBZX84C3V9ET1G have a defined pin 2 function?

No - pin 2 of SZBZX84C3V9ET1G is explicitly designated as "No Connection" per the mechanical outline (Style 8) and electrical characteristics table. It is an internal leadframe stub with no electrical connection to the die; leaving it unconnected avoids unintended coupling or thermal path interference in layout design.

What is the thermal resistance junction-to-ambient for SZBZX84C3V9ET1G on FR-5 board?

The thermal resistance junction-to-ambient (R_JA) for SZBZX84C3V9ET1G is 500 °C/W when mounted on FR-5 board, with total power dissipation derated at 2.0 mW/°C above 25°C ambient. This value is derived from the Maximum Ratings table on page 1 of the onsemi datasheet and governs safe continuous operation under natural convection cooling.

SZBZX84C3V9ET1G 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):: 3.9 V

Tolerance:: ±5%

Power - Max:: 225 mW

Impedance (Max) (Zzt):: 90 Ohms

Current - Reverse Leakage @ Vr:: 3 µA @ 1 V

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

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

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

SZBZX84C3V9ET1G FAQ

1.How can I place an order for SZBZX84C3V9ET1G through Aetrix?

Please submit a Request for Quotation (RFQ) for SZBZX84C3V9ET1G 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 SZBZX84C3V9ET1G reliable?

The price and inventory of SZBZX84C3V9ET1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SZBZX84C3V9ET1G is usually 5 days.

3.What payment methods are accepted for SZBZX84C3V9ET1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SZBZX84C3V9ET1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SZBZX84C3V9ET1G?

SZBZX84C3V9ET1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SZBZX84C3V9ET1G 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 SZBZX84C3V9ET1G?

For technical support, including SZBZX84C3V9ET1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SZBZX84C3V9ET1G requirements.

6.How does Aetrix verify that SZBZX84C3V9ET1G is sourced from the original manufacturer or authorized distributors?

All SZBZX84C3V9ET1G 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 SZBZX84C3V9ET1G meets industry standards.

7.What is the process for return or replacement of SZBZX84C3V9ET1G?

All SZBZX84C3V9ET1G units undergo pre-shipment inspection (PSI). If there is an issue with SZBZX84C3V9ET1G, 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 SZBZX84C3V9ET1G part is unused and in its original packaging.

Return procedure for SZBZX84C3V9ET1G:

1.Submit a request within 90 days.

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

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