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onsemi BZX84B18LT3
- Part No.:
- BZX84B18LT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84B18LT3.pdf
- Description:
- DIODE ZENER 18V 225MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:30,000
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Product details
Overview
BZX84B18LT3 from onsemi is a tight-tolerance Zener diode designed for precision voltage regulation in space-constrained circuits, featuring a nominal Zener voltage of 18.0 V at 5 mA test current, ±2.2% tolerance (17.6 V to 18.4 V), 225 mW power dissipation on FR-5 board, and SOT-23 surface-mount package. It serves as a stable reference or overvoltage clamp in portable power management and signal conditioning circuits.
For engineers reviewing the BZX84B18LT3 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage accuracy, dynamic impedance at 5 mA (max 45 Ω), temperature coefficient (±12.6 mV/°C), reverse leakage (<50 nA at 14.4 V), and Pb-free SOT-23 package compatibility with automated assembly.
Technical Context
This device operates as a two-terminal voltage reference using controlled reverse-breakdown conduction, with specified Zener voltage measured under pulsed 5 mA test conditions at 25°C ambient. Its thermal resistance is 556 °C/W junction-to-ambient on FR-5 board, enabling stable regulation up to +150°C junction temperature.
The SOT-23 package integrates an anode (Pin 1), no-connect (Pin 2), and cathode (Pin 3), supporting high-density PCB layouts. ESD robustness exceeds 16 kV per Human Body Model, and it meets AEC-Q101 qualification for automotive-grade reliability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 18.0 V nominal at IZT = 5 mA; ensures precise 18 V reference within ±2.2% (17.6–18.4 V) for calibration-critical circuits |
| Power Dissipation | 225 mW on FR-5 board at 25°C; derates linearly by 1.8 mW/°C above 25°C, limiting continuous operation in thermally constrained environments |
| Zener Impedance (ZZT) | Max 45 Ω at IZT = 5 mA; maintains low output impedance for stable regulation under varying load currents |
| Reverse Leakage Current | <50 nA at VR = 14.4 V; minimizes standby power loss in battery-powered systems |
| Temperature Coefficient | ±12.6 mV/°C at IZT = 5 mA; enables predictable voltage drift compensation in wide-temperature industrial applications |
| Capacitance | 100 pF at VR = 0 V, f = 1 MHz; suitable for low-frequency regulation but not RF bypassing |
| ESD Rating | Class 3 (>16 kV) per HBM; withstands handling and board-level electrostatic discharge without parameter shift |
Pinout & Package
SOT-23 (TO-236) plastic surface-mount package, void-free transfer-molded thermosetting case with corrosion-resistant, solderable finish; maximum soldering temperature 260°C for 10 seconds; polarity indicated by cathode band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode | Connected to lower-potential node in reverse-bias configuration; must be held ≤18 V below cathode to avoid breakdown |
| 2 | No Connection | Internally unconnected; electrically isolated and must remain floating-no PCB trace or pad required |
| 3 | Cathode | Connected to higher-potential node; carries regulated output voltage referenced to anode; marked by polarity band |
Key Features
| Feature | Design Value |
|---|---|
| Tight Zener voltage tolerance | ±2.2% (17.6–18.4 V) at 5 mA enables high-accuracy voltage references without external trimming |
| Low dynamic impedance | 45 Ω max at 5 mA ensures minimal output voltage variation across load current changes |
| High ESD robustness | Class 3 (>16 kV) HBM rating eliminates need for external ESD protection in handheld designs |
| AEC-Q101 qualified | Validated for automotive applications including infotainment power rails and sensor bias networks |
| Pb-free SOT-23 packaging | RoHS-compliant construction supports lead-free reflow processes without reliability degradation |
Applications
| Portable Power Supervision | Industrial Sensor Biasing |
|---|---|
Use Scenario: Monitoring Li-ion battery pack voltage in Bluetooth earbuds to trigger low-battery shutdown before cutoff. IC Role / Device Role / Timing Role: Zener reference for comparator input threshold, providing fixed 18 V trip point independent of supply rail variation. Use Value: Tight 18.0 V ±2.2% tolerance ensures consistent shutdown voltage across production units, reducing field failure rate. |
Use Scenario: Supplying stable bias voltage to a 4–20 mA current-loop pressure transducer in factory automation PLC modules. IC Role / Device Role / Timing Role: Precision shunt regulator maintaining constant 18 V across transducer excitation circuitry. Use Value: Low 45 Ω Zener impedance prevents output droop under transducer load transients, preserving measurement linearity. |
| Automotive CAN Node Protection | Medical Instrument Reference |
Use Scenario: Clamping transient overvoltage on 12 V CAN bus power rail during load-dump events in vehicle body control modules. IC Role / Device Role / Timing Role: Fast-acting shunt protector diverting surge energy away from CAN transceiver ICs. Use Value: 225 mW FR-5 rating and −65°C to +150°C operating range ensure survivability in under-hood thermal cycling. |
Use Scenario: Generating calibrated 18 V reference for analog front-end ADC in portable ECG monitor with battery backup. IC Role / Device Role / Timing Role: Primary voltage reference source for gain-setting resistors and offset trimming networks. Use Value: ±12.6 mV/°C temperature coefficient allows accurate drift modeling and software compensation over clinical operating range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84C18LT3 | Standard-tolerance version: 18.0 V ±5% (17.1–18.9 V), higher ZZT (max 55 Ω), same SOT-23 package | Acceptable where cost sensitivity outweighs voltage accuracy requirements, e.g., non-critical power rail clamping | Select BZX84C18LT3 only if ±5% tolerance satisfies system margin; BZX84B18LT3 required for <±3% error budgets |
| MMSZ4689T1G | 18 V Zener in SOD-123 package; ±5% tolerance; 500 mW power rating; higher thermal resistance (625 °C/W) | Preferred for higher-power dissipation needs but requires larger PCB area and different footprint | Choose MMSZ4689T1G only when >225 mW continuous dissipation is needed; BZX84B18LT3 remains optimal for high-density SOT-23 layouts |
Compared with BZX84C18LT3, the BZX84B18LT3 delivers tighter voltage control critical for precision references, while MMSZ4689T1G trades package size for higher power handling-neither offers the exact combination of SOT-23 footprint, 225 mW rating, and ±2.2% tolerance found in BZX84B18LT3.
Availability
BZX84B18LT3 is available at Aetrix Electronics and suitable for portable electronics, automotive body control modules, and industrial sensor interfaces requiring stable component supply with full RoHS compliance and AEC-Q101 validation.
Supply support for BZX84B18LT3 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, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The BZX84BxxxLT3 series belongs to onsemi's precision Zener voltage regulator product line, engineered for high-accuracy voltage reference and overvoltage protection in miniaturized, high-reliability applications.
FAQ
What is the exact Zener voltage tolerance of the BZX84B18LT3?
The BZX84B18LT3 has a guaranteed Zener voltage range of 17.6 V to 18.4 V at 5 mA test current, corresponding to a ±2.2% tolerance around the nominal 18.0 V value. This tight specification is confirmed in the "BZX84BxxxLT1" electrical characteristics table on page 4 of the official onsemi datasheet revision 14, and distinguishes it from the looser ±5% tolerance of the BZX84C18LT3 variant.
Does the BZX84B18LT3 have a functional Pin 2 connection?
No, Pin 2 of the BZX84B18LT3 is internally unconnected (NC) and must remain electrically floating on the PCB. The device operates as a two-terminal Zener diode between Pin 1 (anode) and Pin 3 (cathode), with Pin 2 serving only as a mechanical placeholder in the SOT-23 package-no trace, pad, or grounding is required or recommended.
Is the BZX84B18LT3 qualified for automotive use?
Yes, the BZX84B18LT3 is AEC-Q101 qualified and PPAP capable, as explicitly stated in the "Features" section of the onsemi datasheet. This qualification covers stress testing for temperature cycling, humidity, mechanical shock, and ESD, making it suitable for automotive applications such as body control modules, infotainment power supplies, and sensor interface circuits.
What is the maximum reverse leakage current for the BZX84B18LT3 at 14.4 V?
The maximum reverse leakage current for the BZX84B18LT3 is 50 nA at VR = 14.4 V, as specified in the "ELECTRICAL CHARACTERISTICS − BZX84BxxxLT1" table on page 4 of the datasheet. This ultra-low leakage supports energy efficiency in battery-powered devices where standby current must be minimized.
Can the BZX84B18LT3 be used in place of the BZX84C18LT3 without design changes?
No-while both share the same SOT-23 package and nominal 18 V rating, the BZX84B18LT3 has tighter ±2.2% tolerance and lower Zener impedance (45 Ω vs. 55 Ω), which may alter regulation stability in existing circuits designed for the C-series' looser spec. Direct substitution requires verification of system-level voltage margin and dynamic response.
BZX84B18LT3 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)
BZX84B18LT3 FAQ
1.How can I place an order for BZX84B18LT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84B18LT3 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 BZX84B18LT3 reliable?
The price and inventory of BZX84B18LT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84B18LT3 is usually 5 days.
3.What payment methods are accepted for BZX84B18LT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84B18LT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84B18LT3?
BZX84B18LT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84B18LT3 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 BZX84B18LT3?
For technical support, including BZX84B18LT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84B18LT3 requirements.
6.How does Aetrix verify that BZX84B18LT3 is sourced from the original manufacturer or authorized distributors?
All BZX84B18LT3 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 BZX84B18LT3 meets industry standards.
7.What is the process for return or replacement of BZX84B18LT3?
All BZX84B18LT3 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84B18LT3, 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 BZX84B18LT3 part is unused and in its original packaging.
Return procedure for BZX84B18LT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84B18LT3 Tags
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MMBZ5240B-7-F
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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SMAZ12-13-F
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