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onsemi BZX84C18LT1
- Part No.:
- BZX84C18LT1
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84C18LT1.pdf
- Description:
- DIODE ZENER 18V 225MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:9,683
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Product details
Overview
BZX84C18LT1 from onsemi is a 18 V, ±5% tolerance Zener diode in SOT-23 package, rated for 225 mW power dissipation at 25°C on FR-5 board, with 45 Ω dynamic impedance at 5 mA test current and 0.05 µA reverse leakage at 14.4 V. It provides precision voltage regulation in space-constrained portable electronics.
For engineers reviewing the BZX84C18LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage (18 V), tolerance (±5%), thermal resistance (556 °C/W), ESD rating (>16 kV HBM), and SOT-23 footprint compatibility with automated assembly.
Technical Context
This device operates as a two-terminal voltage reference, conducting in reverse breakdown to clamp voltage across its cathode-anode terminals. Its Zener mechanism delivers stable regulation at 18 V with temperature coefficient of +12.6 mV/°C and capacitance of 100 pF at 0 V bias and 1 MHz.
The SOT-23 package features void-free thermosetting plastic construction, UL 94 V-0 flammability rating, and polarity band indicating cathode. Pin 2 is internally unconnected - only pins 1 (anode) and 3 (cathode) are electrically active.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage | 18 V nominal, 16.8–19.1 V range at 5 mA - defines regulated output voltage under typical bias |
| Power Dissipation | 225 mW on FR-5 board at 25°C - sets maximum continuous power before thermal derating begins |
| Zener Impedance | 45 Ω max at 5 mA - determines regulation stiffness and AC ripple rejection capability |
| Reverse Leakage | 0.05 µA max at 14.4 V - ensures minimal quiescent current in standby or high-impedance circuits |
| Temperature Coefficient | +12.6 mV/°C - quantifies voltage drift per degree Celsius rise above 25°C |
| Capacitance | 100 pF at 0 V, 1 MHz - impacts high-frequency noise filtering and signal integrity in RF-adjacent designs |
| ESD Rating | Class 3 (>16 kV HBM) - enables robust handling during PCB assembly without external protection |
Pinout & Package
SOT-23 surface-mount package (Case 318, Style 8), 3-pin configuration with pin 2 internally unconnected. Dimensions: 2.80–3.04 mm length × 1.20–1.40 mm width × 0.99–1.26 mm height. Cathode identified by polarity band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Anode | Forward-biased terminal; connects to lower-potential node in regulation path |
| Pin 2 | No Connection | Internally isolated; must remain unconnected on PCB to avoid parasitic coupling |
| Pin 3 | Cathode | Reverse-biased terminal; connects to higher-potential node and regulates voltage drop |
Key Features
| Feature | Design Value |
|---|---|
| Pb-Free Compliant Packaging | RoHS-compliant SOT-23 construction supports lead-free reflow soldering up to 260°C for 10 s |
| High-Density Mounting | Small footprint (2.8 × 1.2 mm) enables placement in tight layouts like smartphone power rails |
| Automated Assembly Optimized | Transfer-molded case geometry and coplanar leads ensure reliable pick-and-place and reflow yield |
| Stable Low-Voltage Regulation | ±5% tolerance and +12.6 mV/°C TC enable predictable 18 V reference in battery-powered systems |
| ESD-Robust Construction | Class 3 HBM rating (>16 kV) eliminates need for external ESD protection in handheld interfaces |
Applications
| Battery Voltage Monitoring | USB Port Overvoltage Clamp |
|---|---|
Use Scenario: Monitoring Li-ion battery pack voltage in portable medical devices to trigger low-battery alerts at 18 V threshold. IC Role / Device Role / Timing Role: Zener reference element providing precise 18 V trip point for comparator input. Use Value: Tight ±5% tolerance ensures consistent alert timing across production units without calibration. | Use Scenario: Protecting downstream USB 3.0 PHY circuitry from transient overvoltage events exceeding 18 V. IC Role / Device Role / Timing Role: Shunt clamping device diverting surge current away from sensitive transceivers. Use Value: 225 mW power rating and 45 Ω Zener impedance enable fast response to 10/1000 µs transients without thermal runaway. |
| Low-Power Sensor Biasing | Industrial PLC Input Protection |
Use Scenario: Providing stable 18 V bias to MEMS pressure sensor ICs in wireless IoT nodes operating from 3.3 V LDOs via charge pump. IC Role / Device Role / Timing Role: Precision voltage reference stabilizing sensor excitation voltage. Use Value: 100 pF capacitance avoids signal distortion in 100 kHz sensor output bandwidth. | Use Scenario: Clamping 24 V DC field inputs in programmable logic controllers to prevent damage from wiring faults or induced surges. IC Role / Device Role / Timing Role: Primary overvoltage protection element on analog input channel. Use Value: >16 kV HBM ESD rating withstands repeated electrostatic discharge during field maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84C18LT3 | Same electrical specs; differs only in tape-and-reel packaging (10,000 pcs vs. 3,000 pcs) | Identical function; selected for high-volume automated assembly lines requiring larger reels | Choose BZX84C18LT3 when optimizing for feeder change frequency and line uptime in mass production. |
| BZX84B18LT1 | Tighter ±2% tolerance (17.6–18.4 V), same 18 V nominal, 45 Ω Zz, and 0.05 µA IR | Used where tighter regulation stability is required, e.g., precision ADC reference buffers | Choose BZX84B18LT1 when system-level accuracy demands sub-1% absolute voltage error at 25°C. |
Compared with BZX84C18LT1, BZX84C18LT3 offers identical performance in larger packaging for production efficiency, while BZX84B18LT1 trades wider tolerance for enhanced precision-enabling selection based on cost-vs-accuracy trade-offs in voltage reference design.
Availability
BZX84C18LT1 is available at Aetrix Electronics and suitable for battery management systems, USB interface protection, low-power sensor biasing, and industrial I/O conditioning requiring stable component supply and long-term lifecycle support.
Supply support for BZX84C18LT1 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 silicon solutions for automotive, industrial, cloud, and consumer electronics.
The BZX84CxxxLT1 series is designed for compact, high-density voltage regulation in portable and space-constrained applications, emphasizing low-profile SOT-23 packaging, Pb-free compliance, and robust ESD performance.
FAQ
What is the Zener voltage tolerance of BZX84C18LT1?
The BZX84C18LT1 has a nominal Zener voltage of 18 V with a tolerance of ±5%, meaning the actual breakdown voltage falls between 16.8 V and 19.1 V when tested at 5 mA (IZT). This tolerance is specified per the standard C-series Zener family and confirmed in the Electrical Characteristics table on page 3 of the official datasheet.
Is pin 2 of BZX84C18LT1 electrically connected?
No, pin 2 of BZX84C18LT1 is not electrically connected - it is an internal no-connect terminal. The device functions exclusively between pin 1 (anode) and pin 3 (cathode), as explicitly stated in the Pinout section on pages 2 and 7 of the datasheet. PCB layout must leave pin 2 unconnected.
What is the maximum power dissipation of BZX84C18LT1 on FR-5 board?
The BZX84C18LT1 is rated for 225 mW total power dissipation on FR-5 board at 25°C ambient temperature. Above 25°C, it derates linearly at 1.8 mW/°C, reaching zero dissipation at approximately 158°C ambient - a value derived directly from the RJA = 556 °C/W specification in the Maximum Ratings table.
Does BZX84C18LT1 have Pb-free packaging options?
Yes, BZX84C18LT1 is available in Pb-free packaging, indicated by the "G" suffix (e.g., BZX84C18LT1G). The base part number BZX84C18LT1 itself is compatible with lead-free reflow processes, with maximum soldering temperature of 260°C for 10 seconds, as documented in the Mechanical Characteristics section.
What is the Zener impedance of BZX84C18LT1 at 5 mA test current?
The BZX84C18LT1 has a maximum Zener impedance (ZZT) of 45 Ω at 5 mA test current (IZT), as specified in the Electrical Characteristics table on page 3. This value reflects dynamic resistance in the breakdown region and directly impacts regulation accuracy under varying load conditions.
BZX84C18LT1 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):
- 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)
BZX84C18LT1 FAQ
1.How can I place an order for BZX84C18LT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84C18LT1 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 BZX84C18LT1 reliable?
The price and inventory of BZX84C18LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C18LT1 is usually 5 days.
3.What payment methods are accepted for BZX84C18LT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C18LT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84C18LT1?
BZX84C18LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84C18LT1 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 BZX84C18LT1?
For technical support, including BZX84C18LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C18LT1 requirements.
6.How does Aetrix verify that BZX84C18LT1 is sourced from the original manufacturer or authorized distributors?
All BZX84C18LT1 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 BZX84C18LT1 meets industry standards.
7.What is the process for return or replacement of BZX84C18LT1?
All BZX84C18LT1 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C18LT1, 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 BZX84C18LT1 part is unused and in its original packaging.
Return procedure for BZX84C18LT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84C18LT1 Tags
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MMBZ5240B-7-F
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onsemi
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