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

onsemi BZX84C3V9LT1

Name: BZX84C3V9LT1
Brand: onsemi
SKU: BZX84C3V9LT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BZX84C3V9LT1

Manufacturer:: onsemi

Category:: Single Zener Diodes

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

Datasheet:: BZX84C3V9LT1.pdf

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

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Product details

Overview

BZX84C3V9LT1 from onsemi is a 3.9 V, ±5% tolerance Zener diode in SOT-23 package, rated for 225 mW power dissipation on FR-5 board at 25°C, with 90 Ω dynamic impedance at 5 mA test current and −2.5 mV/°C temperature coefficient - used for voltage reference and overvoltage protection in portable power rails.

For engineers reviewing the BZX84C3V9LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage (3.9 V), tight thermal coefficient (−2.5 mV/°C), low leakage (≤3 µA at 3 V), and SOT-23 footprint compatibility with space-constrained DC-DC feedback networks and ESD-clamped I/O lines.

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 three test currents (1 mA, 5 mA, 20 mA), enabling stable regulation across varying load conditions in low-power biasing circuits.

The SOT-23 package features Pin 1 (Anode), Pin 2 (No Connection), Pin 3 (Cathode), with cathode polarity marked by a band. It supports Pb-free reflow soldering up to 260°C for 10 seconds and meets UL 94 V-0 flammability rating.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	3.7 V to 4.1 V @ 5 mA - ensures precise 3.9 V nominal regulation with ±5% tolerance for feedback loop references
Power Dissipation	225 mW on FR-5 board @ 25°C - defines maximum continuous power handling before thermal derating begins
Zener Impedance (Z_ZT)	90 Ω @ 5 mA - indicates low AC impedance for stable voltage under small-signal ripple conditions
Reverse Leakage Current	≤3 µA @ 3 V - guarantees minimal quiescent current draw in standby or high-impedance sensing nodes
Temperature Coefficient	−2.5 mV/°C @ 5 mA - enables predictable voltage drift compensation in ambient-temperature-varying applications
Capacitance	450 pF @ 0 V, 1 MHz - impacts high-frequency noise filtering capability and signal integrity in RF-adjacent bias paths

Pinout & Package

SOT-23 (Case 318, Style 8) surface-mount plastic package with void-free thermosetting epoxy, corrosion-resistant finish, and UL 94 V-0 flammability rating. Cathode identified by polarity band.

Pin/Terminal	Circuit Role	Design Meaning
1	Anode	Connected to lower-potential node in reverse-biased configuration; forms current entry point during Zener conduction
2	No Connection	Internally unconnected; must remain floating - no PCB trace or pad should tie to this terminal
3	Cathode	Connected to higher-potential node; polarity band aligns with this pin for correct orientation during automated placement

Key Features

Feature	Design Value
Pb-Free Compliant Packaging	Meets RoHS Directive 2011/65/EU; compatible with lead-free reflow profiles up to 260°C
ESD Robustness	Class 3 (>16 kV) per Human Body Model - protects against electrostatic discharge during handling and assembly
High-Density Mounting	0.95 mm × 1.3 mm footprint - enables integration into compact PCB layouts such as smartphone PMIC decoupling networks
Thermal Stability	Junction temperature range −65°C to +150°C - supports operation in automotive cabin and industrial control environments

Applications

Portable Power Regulation	I/O Line Protection
Use Scenario: Providing stable 3.9 V reference for LDO feedback divider in Bluetooth headset battery management. IC Role / Device Role / Timing Role: Voltage reference element defining regulated output voltage via resistor divider ratio. Use Value: Maintains ±1% output accuracy across −20°C to +70°C ambient due to known −2.5 mV/°C TC and low Z_ZT.	Use Scenario: Clamping UART TX line against transient surges in handheld medical sensor interface. IC Role / Device Role / Timing Role: Bidirectional transient voltage suppressor leveraging forward conduction (0.9 V) and reverse Zener action (3.9 V). Use Value: Limits voltage excursion to ≤4.1 V while adding only 450 pF capacitance - preserves 1 Mbps signal integrity.
ADC Reference Stabilization	Microcontroller Reset Circuit
Use Scenario: Biasing precision ADC reference input in battery-powered environmental monitor. IC Role / Device Role / Timing Role: Low-drift voltage source replacing larger ceramic capacitor-based RC filter for improved long-term stability. Use Value: Delivers <3 µA leakage at 3 V bias, minimizing error contribution to 16-bit ADC full-scale measurement.	Use Scenario: Generating clean reset threshold for ARM Cortex-M0+ MCU in smart lock controller. IC Role / Device Role / Timing Role: Threshold detector in RC-reset network where Zener clamps capacitor voltage at 3.9 V. Use Value: Enables deterministic reset release timing independent of supply ramp rate, with guaranteed 90 Ω Zener impedance limiting current surge.

Portable Power Regulation

I/O Line Protection

Use Scenario: Providing stable 3.9 V reference for LDO feedback divider in Bluetooth headset battery management.

IC Role / Device Role / Timing Role: Voltage reference element defining regulated output voltage via resistor divider ratio.

Use Value: Maintains ±1% output accuracy across −20°C to +70°C ambient due to known −2.5 mV/°C TC and low Z_ZT.

Use Scenario: Clamping UART TX line against transient surges in handheld medical sensor interface.

IC Role / Device Role / Timing Role: Bidirectional transient voltage suppressor leveraging forward conduction (0.9 V) and reverse Zener action (3.9 V).

Use Value: Limits voltage excursion to ≤4.1 V while adding only 450 pF capacitance - preserves 1 Mbps signal integrity.

ADC Reference Stabilization

Microcontroller Reset Circuit

Use Scenario: Biasing precision ADC reference input in battery-powered environmental monitor.

IC Role / Device Role / Timing Role: Low-drift voltage source replacing larger ceramic capacitor-based RC filter for improved long-term stability.

Use Value: Delivers <3 µA leakage at 3 V bias, minimizing error contribution to 16-bit ADC full-scale measurement.

Use Scenario: Generating clean reset threshold for ARM Cortex-M0+ MCU in smart lock controller.

IC Role / Device Role / Timing Role: Threshold detector in RC-reset network where Zener clamps capacitor voltage at 3.9 V.

Use Value: Enables deterministic reset release timing independent of supply ramp rate, with guaranteed 90 Ω Zener impedance limiting current surge.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBZ5227BLT1	3.6 V nominal, ±5%, 225 mW, same SOT-23 package but higher Z_ZT (150 Ω @ 20 mA)	Lower regulation accuracy at higher currents; less suitable for precision feedback loops	Select when cost sensitivity outweighs tight voltage tolerance requirements
BZX84C3V9LT3G	Identical electrical specs; differs only in tape-and-reel quantity (10,000 vs. 3,000) and Pb-free marking suffix	No functional difference - identical performance and layout compatibility	Choose for high-volume production requiring larger reel size and RoHS compliance documentation

Compared with BZX84C3V9LT1, MMBZ5227BLT1 offers lower Zener voltage and higher impedance, reducing regulation fidelity in precision analog paths, while BZX84C3V9LT3G provides identical electrical behavior with optimized logistics packaging - making it a drop-in replacement for volume manufacturing without design change.

Availability

BZX84C3V9LT1 is available at Aetrix Electronics and suitable for portable electronics, I/O protection circuits, and microcontroller reset networks requiring stable component supply, consistent parametric performance, and RoHS-compliant sourcing.

Supply support for BZX84C3V9LT1 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BZX84C3V9LT1 belongs to the BZX84CxxxLT1 series of standard-tolerance Zener diodes designed specifically for compact, low-power voltage regulation and protection in high-density portable and embedded systems.

FAQ

What is the Zener voltage tolerance of BZX84C3V9LT1?

The BZX84C3V9LT1 has a nominal Zener voltage of 3.9 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 3.7 V and 4.1 V when tested at 5 mA. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the official datasheet, and applies specifically to the BZX84C3V9LT1 variant - not the tighter-tolerance BZX84B series.

Does BZX84C3V9LT1 have a connection on Pin 2?

No, Pin 2 of the BZX84C3V9LT1 is internally unconnected (NC). The device uses only Pins 1 (Anode) and 3 (Cathode) for operation. This is explicitly stated in the "Pinout: 1-Anode, 2-No Connection, 3-Cathode" note on page 3 of the datasheet and verified in the Package Dimensions diagram on page 7.

What is the maximum reverse leakage current for BZX84C3V9LT1 at 3 V?

The maximum reverse leakage current for BZX84C3V9LT1 at VR = 3 V is 3 µA, as specified in the Electrical Characteristics table on page 3. This value is measured at TA = 25°C and reflects worst-case off-state current - critical for ultra-low-power applications like battery-backed real-time clocks where BZX84C3V9LT1 may serve as a voltage clamp.

Can BZX84C3V9LT1 be used in place of BZX84C3V3LT1?

No - BZX84C3V9LT1 and BZX84C3V3LT1 are distinct parts with different Zener voltages (3.9 V vs. 3.3 V), impedance profiles (90 Ω vs. 95 Ω), and leakage limits (3 µA vs. 5 µA). Substitution would alter circuit regulation points and is not supported by datasheet cross-reference data or manufacturer application guidance.

Is BZX84C3V9LT1 RoHS compliant?

Yes, BZX84C3V9LT1 is RoHS compliant. The "G" suffix in the ordering code (BZX84C3V9LT1, G*) explicitly denotes Pb-free packaging, and the datasheet confirms Pb-free availability in the Ordering Information section on page 2 and the Electrical Characteristics footnote on page 3.

BZX84C3V9LT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: BZX84CxxxLT1

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)

BZX84C3V9LT1 FAQ

1.How can I place an order for BZX84C3V9LT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BZX84C3V9LT1 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 BZX84C3V9LT1 reliable?

The price and inventory of BZX84C3V9LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C3V9LT1 is usually 5 days.

3.What payment methods are accepted for BZX84C3V9LT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C3V9LT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BZX84C3V9LT1?

BZX84C3V9LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BZX84C3V9LT1 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 BZX84C3V9LT1?

For technical support, including BZX84C3V9LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C3V9LT1 requirements.

6.How does Aetrix verify that BZX84C3V9LT1 is sourced from the original manufacturer or authorized distributors?

All BZX84C3V9LT1 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 BZX84C3V9LT1 meets industry standards.

7.What is the process for return or replacement of BZX84C3V9LT1?

All BZX84C3V9LT1 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C3V9LT1, 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 BZX84C3V9LT1 part is unused and in its original packaging.

Return procedure for BZX84C3V9LT1:

1.Submit a request within 90 days.

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

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