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onsemi BZX84C18ET3G
- Part No.:
- BZX84C18ET3G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84C18ET3G.pdf
- Description:
- DIODE ZENER 18V 225MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:20,000
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Product details
Overview
BZX84C18ET3G from onsemi is a 250 mW, 18 V nominal Zener voltage regulator diode in SOT-23 package, designed for precision voltage reference and overvoltage protection in space-constrained circuits. It delivers 18.0 V ±0.9 V Zener voltage at 5 mA test current, exhibits 45 Ω dynamic impedance at 5 mA, supports ≤0.05 μA reverse leakage at 14.4 V, and operates across −65°C to +150°C junction temperature range - used in portable power rails and voltage-clamped I/O interfaces.
For engineers reviewing the BZX84C18ET3G datasheet, pinout, applications, or equivalent options, key selection criteria include its 18 V regulation tolerance, thermal coefficient of +12.4 mV/°C, ESD rating >16 kV HBM, 225 W peak pulse power capability, and compatibility with automated SMT assembly on FR-5 or alumina substrates.
Technical Context
This device functions as a two-terminal shunt voltage regulator, operating in reverse breakdown mode with cathode-anode polarity. Its Zener voltage is specified at three test currents (1 mA, 5 mA, and 20 mA), enabling stable reference generation under varying load conditions.
The BZX84C18ET3G features a temperature coefficient of +12.4 mV/°C at 5 mA, indicating positive drift with rising temperature - critical for biasing networks requiring predictable thermal behavior. Its 45 Ω dynamic impedance at 5 mA ensures low output impedance in regulation, while 100 pF capacitance at 0 V bias minimizes high-frequency coupling in signal-path clamping applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 16.8–19.1 V @ 5 mA - defines stable regulation window for 18 V nominal rail |
| Dynamic Impedance (ZZT) | 45 Ω @ 5 mA - determines output voltage deviation under load transients |
| Reverse Leakage Current (IR) | ≤0.05 μA @ 14.4 V - ensures minimal quiescent current in standby mode |
| Power Dissipation (PD) | 250 mW on FR-5 board - sets maximum continuous DC power handling |
| ESD Rating | Class 3 (>16 kV HBM) - enables robust handling in manual and automated assembly |
| Capacitance (C) | 100 pF @ 0 V, 1 MHz - impacts high-frequency noise filtering and signal integrity |
| Thermal Coefficient | +12.4 mV/°C @ 5 mA - quantifies voltage drift per degree Celsius for thermal design margining |
Pinout & Package
SOT-23 plastic surface-mount package (Case 318, Style 8), void-free thermosetting epoxy body with corrosion-resistant solderable finish; cathode indicated by band; UL 94 V-0 flammability rating; max soldering temperature 260°C for 10 seconds.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Anode) | Current entry terminal in forward bias; connected to lower-potential node in Zener operation | Must be tied to ground or reference potential when used as shunt regulator |
| 2 (No Connection) | Internally unconnected lead | No PCB trace or pad required; must remain floating - not bonded internally |
| 3 (Cathode) | Current exit terminal in forward bias; higher-potential node in Zener operation | Connected to regulated voltage rail; carries full Zener current during clamping |
Key Features
| Feature | Design Value |
|---|---|
| 250 mW power rating on FR-5 board | Enables compact voltage regulation without heatsinking in low-power portable designs |
| ESD robustness >16 kV (HBM) | Eliminates need for external ESD protection in handheld and consumer interface circuits |
| Peak pulse power 225 W (8 × 20 μs) | Withstands transient surges such as IEC 61000-4-5 level 3 without failure |
| Pb-free and RoHS-compliant construction | Meets global environmental compliance requirements for industrial and automotive supply chains |
| Small SOT-23 footprint (2.9 × 1.3 × 1.0 mm) | Supports high-density PCB layouts in smartphones, wearables, and IoT sensor nodes |
Applications
| USB Port Protection | Microcontroller I/O Clamping |
|---|---|
|
Use Scenario: Protecting USB 5 V data lines from ESD and overvoltage events in portable accessories. IC Role / Device Role / Timing Role: Shunt clamp placed between D+ and ground, triggered above 5.5 V. Use Value: Leverages 100 pF capacitance and >16 kV HBM rating to suppress fast transients without distorting signal integrity. |
Use Scenario: Limiting GPIO voltage excursions beyond absolute maximum ratings in battery-powered MCU systems. IC Role / Device Role / Timing Role: Bidirectional clamp referenced to VDD, conducting only during overvoltage. Use Value: 0.05 μA leakage at 14.4 V preserves battery life; 45 Ω ZZT ensures rapid clamping response. |
| Low-Power Sensor Reference | DC-DC Feedback Divider Clamp |
|
Use Scenario: Providing stable 18 V reference for analog front-end gain stages in industrial sensors. IC Role / Device Role / Timing Role: Precision shunt reference in parallel with high-impedance op-amp input. Use Value: ±0.9 V tolerance at 5 mA and +12.4 mV/°C TC enable predictable calibration across temperature. |
Use Scenario: Preventing feedback node overvoltage in isolated flyback converters during startup or fault. IC Role / Device Role / Timing Role: Zener connected across optocoupler input to limit LED current surge. Use Value: 225 W pulse rating absorbs energy from transformer leakage spikes without degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBZ5257BLT1 | 18 V nominal, 500 mW rating, SOT-23, +12 mV/°C TC, 30 Ω ZZT @ 20 mA | Higher power and lower impedance suit higher-current regulation; larger thermal mass | Select when >250 mW continuous dissipation or <30 Ω dynamic impedance is required |
| BZX84-C18-7-F | 18 V nominal, 250 mW, SOT-23, +12.5 mV/°C TC, 50 Ω ZZT @ 5 mA, same marking and RoHS status | Identical regulation spec but different manufacturer (Diodes Inc.) and tape/reel packaging | Use for dual-sourcing where identical electrical performance and SOT-23 footprint are mandatory |
Compared with BZX84C18ET3G, MMBZ5257BLT1 offers higher power headroom and lower impedance at cost of larger thermal footprint, while BZX84-C18-7-F provides drop-in second-source compatibility with no layout or firmware changes.
Availability
BZX84C18ET3G is available at Aetrix Electronics and suitable for USB port protection, microcontroller I/O clamping, low-power sensor reference, DC-DC feedback divider clamp, and portable power rail stabilization requiring stable component supply and long-term lifecycle support.
Supply support for BZX84C18ET3G 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 specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BZX84CxxxET3G series belongs to onsemi's precision Zener voltage regulator product line, engineered for reliable voltage reference and transient suppression in high-density, low-power portable and embedded systems.
FAQ
What is the Zener voltage tolerance of BZX84C18ET3G at 5 mA test current?
The BZX84C18ET3G has a Zener voltage range of 16.8 V to 19.1 V at 5 mA, corresponding to a nominal 18 V with ±0.9 V absolute tolerance. This specification is verified per onsemi's Electrical Characteristics table and defines the guaranteed regulation window under standard test conditions (TA = 25°C). The BZX84C18ET3G maintains this tolerance across its qualified operating temperature range.
Does BZX84C18ET3G have a connection on pin 2?
No, pin 2 of the BZX84C18ET3G is internally unconnected (NC) and must remain floating on the PCB. The device uses only pins 1 (anode) and 3 (cathode) for electrical operation. This is confirmed in the marking diagram and "Pinout" section of the official datasheet, which explicitly states "2-No Connection" for the SOT-23 package configuration of the BZX84C18ET3G.
What is the maximum reverse leakage current for BZX84C18ET3G, and at what voltage is it specified?
The BZX84C18ET3G specifies a maximum reverse leakage current of 0.05 μA at a reverse voltage of 14.4 V (80% of nominal 18 V), per the Electrical Characteristics table. This low leakage ensures minimal power loss in battery-critical applications and supports stable reference performance in high-impedance bias networks using the BZX84C18ET3G.
Can BZX84C18ET3G be used in automotive applications?
The standard BZX84C18ET3G is not AEC-Q101 qualified; however, the SZBZX84C18ET3G variant - with identical electrical specs and SOT-23 package - is automotive-grade, AEC-Q101 qualified, and PPAP capable. For automotive use, designers must specify the SZ-prefix part; the BZX84C18ET3G itself is intended for commercial and industrial applications per onsemi's ordering information.
What is the thermal resistance junction-to-ambient for BZX84C18ET3G on an FR-5 board?
The BZX84C18ET3G has a thermal resistance of 500°C/W junction-to-ambient (RJA) when mounted on an FR-5 board, with 250 mW total power dissipation derated above 25°C at 2.0 mW/°C. This value directly determines allowable ambient temperature rise under continuous operation and is critical for thermal design validation of circuits using the BZX84C18ET3G.
BZX84C18ET3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 18 V
- Tolerance:
- ±6%
- Power - Max:
- 225 mW
- Impedance (Max) (Zzt):
- 45 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 12.6 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)
BZX84C18ET3G FAQ
1.How can I place an order for BZX84C18ET3G through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84C18ET3G 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 BZX84C18ET3G reliable?
The price and inventory of BZX84C18ET3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C18ET3G is usually 5 days.
3.What payment methods are accepted for BZX84C18ET3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C18ET3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84C18ET3G?
BZX84C18ET3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84C18ET3G 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 BZX84C18ET3G?
For technical support, including BZX84C18ET3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C18ET3G requirements.
6.How does Aetrix verify that BZX84C18ET3G is sourced from the original manufacturer or authorized distributors?
All BZX84C18ET3G 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 BZX84C18ET3G meets industry standards.
7.What is the process for return or replacement of BZX84C18ET3G?
All BZX84C18ET3G units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C18ET3G, 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 BZX84C18ET3G part is unused and in its original packaging.
Return procedure for BZX84C18ET3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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