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

onsemi BZX84C3V9ET1

Name: BZX84C3V9ET1
Brand: onsemi
SKU: BZX84C3V9ET1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX84C3V9ET1

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: BZX84C3V9ET1.pdf

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

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Product details

Overview

BZX84C3V9ET1 from onsemi is a 3.9 V, 225 mW surface-mount Zener diode in SOT-23 package, rated for 5 mA test current with ±0.2 V tolerance (3.7–4.1 V), 90 Ω dynamic impedance at 5 mA, and −2.5 mV/°C temperature coefficient. It regulates voltage in low-power biasing, reference, and overvoltage protection circuits in portable electronics.

For engineers reviewing the BZX84C3V9ET1 datasheet, pinout, applications, or equivalent options, key selection criteria include its precise 3.9 V nominal Zener voltage, low leakage (≤3.0 µA at 1.0 V), ESD robustness (>16 kV HBM), and compatibility with high-density automated PCB assembly.

Technical Context

This device operates as a two-terminal voltage reference by exploiting controlled reverse breakdown in a silicon p-n junction. Its Zener voltage is specified at IZT = 5 mA, with guaranteed min/max bounds (3.7 V / 4.1 V) and tight dynamic impedance (90 Ω) ensuring stable regulation under varying load currents.

Thermal performance is defined by R_JA = 556 °C/W on FR-5 board and T_J range of −65 °C to +150 °C. The SOT-23 package features a cathode band marking, no internal connection on pin 2, and Pb-free construction compliant with RoHS.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	3.9 V nominal @ 5 mA; actual range 3.7–4.1 V ensures predictable clamping in 3.3 V system rails.
Power Dissipation (P_D)	225 mW on FR-5 board at 25°C; derates 1.8 mW/°C above ambient - supports continuous operation up to ~85°C in typical layouts.
Zener Impedance (Z_ZT)	90 Ω @ 5 mA - limits output voltage variation under small-signal load changes, critical for precision references.
Reverse Leakage (I_R)	≤3.0 µA @ V_R = 1.0 V - minimizes quiescent current in battery-powered bias networks.
Temperature Coefficient	−2.5 mV/°C @ 5 mA - enables predictable drift compensation in temperature-sensitive analog circuits.
Capacitance (C)	450 pF @ V_R = 0 V, f = 1 MHz - impacts high-frequency noise filtering and transient response in decoupling roles.
ESD Rating	Class 3 (>16 kV) per HBM - provides robust handling during automated assembly and end-user integration.

Pinout & Package

SOT-23 (Case 318, Style 8) surface-mount package with 3 terminals: anode (pin 1), no connection (pin 2), cathode (pin 3). Cathode identified by polarity band. Package dimensions: 2.90 mm × 1.30 mm × 0.95 mm (L × W × H).

Pin/Terminal	Circuit Role	Design Meaning
1	Anode	Connected to lower-potential node in reverse-bias configuration; must be held ≤3.9 V below cathode for regulation.
2	No Connection	Internally unconnected; electrically isolated - no routing or soldering required.
3	Cathode	Connected to regulated voltage rail; polarity band on package identifies this terminal for correct orientation.

Key Features

Feature	Design Value
225 mW power rating on FR-5 board	Enables use in space-constrained, low-power applications without external heat sinking.
ESD robustness >16 kV (HBM)	Eliminates need for additional ESD protection in handheld and portable designs.
Pb-free and RoHS-compliant packaging	Meets global environmental compliance requirements without sacrificing electrical performance.
Small SOT-23 footprint (2.9 × 1.3 mm)	Supports high-density PCB layouts in smartphones, wearables, and IoT sensor nodes.
Stable Zener voltage across −65°C to +150°C	Ensures reliable reference behavior in automotive under-hood and industrial control environments.

Applications

Low-Voltage Bias Reference	Overvoltage Clamp Protection
Use Scenario: Providing stable 3.9 V reference for op-amp input biasing or ADC reference divider in battery-powered sensors. IC Role / Device Role / Timing Role: Two-terminal passive voltage reference establishing fixed DC potential relative to ground. Use Value: Tight 3.7–4.1 V tolerance and low 90 Ω Z_ZT minimize reference drift under load, improving measurement accuracy.	Use Scenario: Clamping I/O line voltage to protect 3.3 V logic inputs from transient surges in USB or GPIO interfaces. IC Role / Device Role / Timing Role: Reverse-biased shunt regulator diverting excess current when voltage exceeds 3.9 V. Use Value: Fast response to transients combined with 225 W peak pulse rating (8 × 20 µs) absorbs energy without failure.
Portable Power Rail Stabilization	High-Density Board Voltage Monitoring
Use Scenario: Stabilizing LDO feedback node or microcontroller reset threshold in compact wearables. IC Role / Device Role / Timing Role: Passive voltage stabilization element maintaining consistent trip point despite supply ripple. Use Value: Low 3.0 µA leakage at 1.0 V preserves battery life while delivering accurate 3.9 V threshold detection.	Use Scenario: Monitoring 3.3 V rail integrity in multi-layer smartphone PCBs where board area is at premium. IC Role / Device Role / Timing Role: Compact voltage verification node placed near critical ICs for localized monitoring. Use Value: SOT-23 footprint (2.9 × 1.3 mm) allows placement directly adjacent to SoC or PMIC without layout compromise.

Low-Voltage Bias Reference

Overvoltage Clamp Protection

Use Scenario: Providing stable 3.9 V reference for op-amp input biasing or ADC reference divider in battery-powered sensors.

IC Role / Device Role / Timing Role: Two-terminal passive voltage reference establishing fixed DC potential relative to ground.

Use Value: Tight 3.7–4.1 V tolerance and low 90 Ω Z_ZT minimize reference drift under load, improving measurement accuracy.

Use Scenario: Clamping I/O line voltage to protect 3.3 V logic inputs from transient surges in USB or GPIO interfaces.

IC Role / Device Role / Timing Role: Reverse-biased shunt regulator diverting excess current when voltage exceeds 3.9 V.

Use Value: Fast response to transients combined with 225 W peak pulse rating (8 × 20 µs) absorbs energy without failure.

Portable Power Rail Stabilization

High-Density Board Voltage Monitoring

Use Scenario: Stabilizing LDO feedback node or microcontroller reset threshold in compact wearables.

IC Role / Device Role / Timing Role: Passive voltage stabilization element maintaining consistent trip point despite supply ripple.

Use Value: Low 3.0 µA leakage at 1.0 V preserves battery life while delivering accurate 3.9 V threshold detection.

Use Scenario: Monitoring 3.3 V rail integrity in multi-layer smartphone PCBs where board area is at premium.

IC Role / Device Role / Timing Role: Compact voltage verification node placed near critical ICs for localized monitoring.

Use Value: SOT-23 footprint (2.9 × 1.3 mm) allows placement directly adjacent to SoC or PMIC without layout compromise.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BZX84C3V9LT1G	Same 3.9 V nominal Zener voltage, identical SOT-23 package, but marked "LT1G" and shipped in 10,000-unit tape-and-reel vs. 3,000 for BZX84C3V9ET1G.	No functional difference; suited for high-volume automated assembly where larger reel size improves line efficiency.	Select BZX84C3V9LT1G when optimizing for production throughput and minimizing reel changeovers.
MMSZ4685T1G	3.9 V Zener, 500 mW rating, same SOT-23 package, but higher power dissipation and 30 Ω Z_ZT @ 5 mA - tighter regulation at higher currents.	Better suited for applications requiring sustained >225 mW dissipation or lower dynamic impedance under variable loads.	Choose MMSZ4685T1G where thermal margin or regulation precision under heavier loading is prioritized over minimal footprint.

Compared with BZX84C3V9ET1, BZX84C3V9LT1G offers identical electrical performance with optimized packaging logistics, while MMSZ4685T1G trades slightly larger thermal footprint for enhanced regulation stability and power handling - enabling design flexibility across cost, density, and performance tiers.

Availability

BZX84C3V9ET1 is available at Aetrix Electronics and suitable for portable electronics, voltage reference circuits, and overvoltage protection systems requiring stable component supply and RoHS-compliant sourcing.

Supply support for BZX84C3V9ET1 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 manufacturer specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BZX84C3V9ET1 belongs to the BZX84CxxxET1 series of 225 mW Zener regulators designed specifically for space-constrained, low-power voltage reference and protection in high-density portable electronics.

FAQ

What is the Zener voltage tolerance of BZX84C3V9ET1 at 5 mA test current?

The BZX84C3V9ET1 has a guaranteed Zener voltage range of 3.7 V to 4.1 V at I_ZT = 5 mA, corresponding to a nominal 3.9 V with ±0.2 V absolute tolerance. This specification is verified per the onsemi datasheet Rev. 6 and ensures predictable clamping behavior in 3.3 V system interfaces where BZX84C3V9ET1 is commonly deployed.

Does BZX84C3V9ET1 have a connected pin 2, and what is its function?

No, pin 2 of the BZX84C3V9ET1 is internally not connected (NC). As confirmed in the official onsemi datasheet, the SOT-23 package uses pin 1 for anode, pin 2 as NC, and pin 3 for cathode. This configuration eliminates ambiguity in PCB layout and prevents incorrect routing - a key reliability factor in automated assembly of BZX84C3V9ET1.

What is the maximum reverse leakage current for BZX84C3V9ET1, and at what voltage is it specified?

The BZX84C3V9ET1 exhibits a maximum reverse leakage current of 3.0 µA at V_R = 1.0 V, as specified in the onsemi Electrical Characteristics table. This low leakage supports ultra-low-power operation in battery-backed circuits and ensures minimal parasitic loading on sensitive bias nodes where BZX84C3V9ET1 serves as a reference.

Can BZX84C3V9ET1 be used in automotive under-hood applications?

Yes, BZX84C3V9ET1 supports junction temperatures from −65°C to +150°C and is qualified for industrial temperature ranges. While not AEC-Q200 certified, its wide T_J range and stable −2.5 mV/°C temperature coefficient make BZX84C3V9ET1 suitable for non-safety-critical under-hood functions such as sensor biasing or auxiliary rail monitoring where full automotive qualification is not mandated.

Is BZX84C3V9ET1 RoHS-compliant and lead-free?

Yes, the "G" suffix in BZX84C3V9ET1G explicitly denotes a Pb-free, RoHS-compliant package per onsemi documentation. The device meets EU RoHS Directive 2011/65/EU requirements and uses matte tin lead finish compatible with standard SnPb and lead-free soldering processes up to 260°C for 10 seconds.

BZX84C3V9ET1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

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:: -

Qualification:: -

Mounting Type:: Surface Mount

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

BZX84C3V9ET1 FAQ

1.How can I place an order for BZX84C3V9ET1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX84C3V9ET1 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 BZX84C3V9ET1 reliable?

The price and inventory of BZX84C3V9ET1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C3V9ET1 is usually 5 days.

3.What payment methods are accepted for BZX84C3V9ET1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C3V9ET1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX84C3V9ET1?

BZX84C3V9ET1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX84C3V9ET1 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 BZX84C3V9ET1?

For technical support, including BZX84C3V9ET1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C3V9ET1 requirements.

6.How does Aetrix verify that BZX84C3V9ET1 is sourced from the original manufacturer or authorized distributors?

All BZX84C3V9ET1 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 BZX84C3V9ET1 meets industry standards.

7.What is the process for return or replacement of BZX84C3V9ET1?

All BZX84C3V9ET1 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C3V9ET1, 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 BZX84C3V9ET1 part is unused and in its original packaging.

Return procedure for BZX84C3V9ET1:

1.Submit a request within 90 days.

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

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