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onsemi BZX84C3V9
- Part No.:
- BZX84C3V9
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84C3V9.pdf
- Description:
- DIODE ZENER 3.9V 250MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:290,900
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Product details
Overview
BZX84C3V9 from Fairchild Semiconductor is a 3.9 V, ±5% tolerance Zener diode in SOT-23 package, rated for 250 mW power dissipation at 25°C ambient, with 30 Ω dynamic impedance at 20 mA and 5.0 μA reverse leakage at 1.0 V, used for precision voltage regulation and reference in low-power analog circuits.
For engineers reviewing the BZX84C3V9 datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance, dynamic impedance at specified test current, thermal resistance (RθJA = 465°C/W), and SOT-23 footprint compatibility in space-constrained PCB designs.
Technical Context
The BZX84C3V9 operates as a silicon planar epitaxial Zener diode optimized for stable voltage reference in biasing, overvoltage protection, and signal clamping. Its 3.9 V nominal breakdown is specified at IZ = 5.0 mA (3.7–4.1 V), with tighter bounds at IZ = 20 mA (4.1–4.7 V) and higher impedance (600 Ω) at IZ = 1.0 mA.
It exhibits a negative temperature coefficient of –3.5 mV/°C at 5.0 mA and junction capacitance of 450 pF at VR = 0 V, f = 1 MHz. The device is rated for TJ = –55 to +150°C and mounted on FR-4 PCB per JEDEC standard layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 3.7–4.1 V at IZ = 5.0 mA - defines tight regulation window for 3.3 V rail supervision or 3.9 V reference generation |
| Zener Impedance (ZZ) | 30 Ω at IZ = 20 mA - ensures minimal output voltage shift under load variation in feedback networks |
| Power Dissipation (PD) | 250 mW at TA = 25°C - limits continuous operation to ≤10 mA average current in ambient PCB environments |
| Reverse Leakage (IR) | 5.0 μA max at VR = 1.0 V - guarantees low quiescent current draw in battery-powered voltage monitor circuits |
| Junction-to-Ambient RθJA | 465°C/W - requires thermal derating above 25°C ambient; full power only viable with minimal board copper |
| Tolerance | ±5% (C-grade) - enables predictable threshold setting without post-calibration in cost-sensitive consumer designs |
| Capacitance (Cap) | 450 pF at VR = 0 V, 1 MHz - impacts high-frequency noise coupling in RF bias or fast-switching clamp applications |
Pinout & Package
SOT-23 surface-mount plastic package with gull-wing leads; standardized 3-pin outline per JEDEC TO-236AB. Cathode marked by band on lead 2 side.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Anode) | Forward conduction terminal | Connected to lower-potential node in reverse-biased Zener configuration; carries forward current up to 250 mA peak |
| 2 (Cathode) | Zener breakdown terminal | Connected to higher-potential node; defines regulated output voltage referenced to anode; thermal path to PCB via cathode pad |
| 3 (Anode) | Redundant anode connection | Electrically tied to Pin 1 internally; provides mechanical stability and dual-anode solder joint reliability in automated assembly |
Key Features
| Feature | Design Value |
|---|---|
| ±5% Zener voltage tolerance | Enables consistent trip-point setting across production batches without individual trimming in voltage supervisor ICs |
| Low 30 Ω dynamic impedance at 20 mA | Maintains <1% output deviation under ±2 mA load transients in analog sensor biasing circuits |
| 450 pF junction capacitance | Supports DC and low-frequency (<100 kHz) regulation; avoids signal distortion in audio bias networks |
| –3.5 mV/°C tempco at 5 mA | Allows predictable drift compensation in temperature-stable references when paired with positive-coefficient components |
| SOT-23 footprint compatibility | Direct drop-in replacement for other BZX84 series devices and industry-standard 3.3–33 V Zeners in existing layouts |
Applications
| Voltage Reference for ADC Biasing | Overvoltage Clamp in USB Interface |
|---|---|
Use Scenario: Providing stable 3.9 V reference to 12-bit SAR ADC input buffer in portable medical sensor module. IC Role / Device Role / Timing Role: Zener diode operating in reverse breakdown to fix reference potential independent of supply ripple. Use Value: 30 Ω impedance ensures <0.5 LSB error under 100 µA load variation; ±5% tolerance meets system-level 1% absolute accuracy requirement. | Use Scenario: Clamping D+ line to 3.9 V against ESD transients during USB 2.0 hot-plug events in industrial HMI panel. IC Role / Device Role / Timing Role: Fast-acting shunt protector absorbing >8 kV HBM surges while limiting voltage excursion below USB PHY damage threshold. Use Value: 5.0 μA IR at 1.0 V prevents false triggering during idle state; 250 mW rating sustains 100 ns pulses without thermal runaway. |
| Microcontroller Reset Threshold | Low-Power Sensor Biasing |
Use Scenario: Setting brown-out detection threshold at 3.9 V for ARM Cortex-M0+ MCU in battery-operated IoT node. IC Role / Device Role / Timing Role: Precision voltage divider element defining reset assertion level relative to VDD. Use Value: Tight 3.7–4.1 V range at 5 mA ensures deterministic reset timing across –40 to +85°C; 465°C/W RθJA supports operation without heatsink. | Use Scenario: Biasing photodiode anode in optical smoke detector front-end amplifier. IC Role / Device Role / Timing Role: Low-noise DC bias source establishing fixed reverse-bias voltage across sensing junction. Use Value: 450 pF capacitance avoids high-frequency gain peaking; –3.5 mV/°C tempco aligns with op-amp offset drift for net zero temperature error. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBZ5226BS-7-F (Diodes Inc.) | Same 3.9 V nominal, ±5%, but 350 mW PD and 25 Ω ZZ at 20 mA; SOT-23 package | Higher power margin supports longer surge clamping; lower impedance improves regulation in active feedback loops | Select when >250 mW transient energy absorption or sub-30 Ω impedance is required without changing layout |
| 1SMA5914BT3G (ON Semiconductor) | 3.9 V, ±5%, 1.5 W PD, DO-214AC package; 10× larger footprint and thermal mass | Designed for high-energy surge suppression; unsuitable for space-constrained PCBs where SOT-23 is mandatory | Select only when thermal robustness outweighs size constraints-requires PCB redesign and requalification |
Compared with MMBZ5226BS-7-F and 1SMA5914BT3G, the BZX84C3V9 delivers optimal balance of SOT-23 miniaturization, 250 mW capability, and 30 Ω impedance for cost-sensitive, volume-production analog subsystems requiring precise 3.9 V regulation.
Availability
BZX84C3V9 is available at Aetrix Electronics and suitable for voltage reference, overvoltage protection, microcontroller reset circuitry, and low-power sensor biasing requiring stable component supply across automotive infotainment, industrial control, and consumer electronics programs.
Supply support for BZX84C3V9 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
Fairchild Semiconductor was a U.S.-based semiconductor company acquired by ON Semiconductor in 2016, known for high-reliability discrete and analog products targeting industrial, computing, and consumer markets.
The BZX84 series was designed as a general-purpose, low-cost Zener diode family for precision voltage regulation in space-constrained, low-power applications-emphasizing tight tolerance, repeatable breakdown, and SOT-23 manufacturability.
FAQ
What is the nominal Zener voltage and tolerance of the BZX84C3V9?
The BZX84C3V9 has a nominal Zener voltage of 3.9 V with a tolerance of ±5%, specified at test current IZ = 5.0 mA (3.7–4.1 V). This tolerance is confirmed in the Electrical Characteristics table of the Fairchild datasheet Rev. 1.10, and applies directly to the BZX84C3V9 variant within the BZX84C3V3–BZX84C33 family.
What is the maximum power dissipation and thermal resistance of the BZX84C3V9?
The BZX84C3V9 has a maximum power dissipation of 250 mW at TA = 25°C, with a junction-to-ambient thermal resistance (RθJA) of 465°C/W. These values assume mounting on a standard FR-4 PCB (76.2 mm × 114.3 mm); derating is required above 25°C ambient per the datasheet's thermal curve.
What is the Zener impedance and reverse leakage current of the BZX84C3V9?
The BZX84C3V9 exhibits 30 Ω dynamic impedance (ZZ) at IZ = 20 mA and a maximum reverse leakage current (IR) of 5.0 μA at VR = 1.0 V. Both parameters are explicitly listed in the Electrical Characteristics table for the BZX84C3V9 row and are critical for evaluating regulation stability and standby power impact in the BZX84C3V9 application.
Is the BZX84C3V9 available in tape-and-reel packaging for automated assembly?
Yes, the BZX84C3V9 is supplied in EIA-481-compliant tape-and-reel format compatible with standard SMT pick-and-place equipment. Standard reel quantities are 3,000 units per reel, and the SOT-23 package orientation follows JEDEC standard carrier tape indexing for the BZX84C3V9.
Does the BZX84C3V9 have a specified junction capacitance, and at what conditions?
Yes, the BZX84C3V9 has a junction capacitance of 450 pF, measured at VR = 0.0 V and f = 1.0 MHz. This value is documented in the "Electrical Characteristics (Continued)" section of the Fairchild datasheet and applies specifically to the BZX84C3V9, not extrapolated from adjacent variants.
BZX84C3V9 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- BZX84
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 3.9 V
- Tolerance:
- ±5.12%
- Power - Max:
- 250 mW
- Impedance (Max) (Zzt):
- 30 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
BZX84C3V9 FAQ
1.How can I place an order for BZX84C3V9 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84C3V9 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 BZX84C3V9 reliable?
The price and inventory of BZX84C3V9 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C3V9 is usually 5 days.
3.What payment methods are accepted for BZX84C3V9?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C3V9 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84C3V9?
BZX84C3V9 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84C3V9 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 BZX84C3V9?
For technical support, including BZX84C3V9 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C3V9 requirements.
6.How does Aetrix verify that BZX84C3V9 is sourced from the original manufacturer or authorized distributors?
All BZX84C3V9 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 BZX84C3V9 meets industry standards.
7.What is the process for return or replacement of BZX84C3V9?
All BZX84C3V9 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C3V9, 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 BZX84C3V9 part is unused and in its original packaging.
Return procedure for BZX84C3V9:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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