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onsemi BZX84B18LT1
- Part No.:
- BZX84B18LT1
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84B18LT1.pdf
- Description:
- DIODE ZENER 18V 225MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:9,469
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Product details
Overview
BZX84B18LT1 from onsemi is a tight-tolerance Zener diode in SOT-23 package, designed for precision voltage regulation at 18 V nominal Zener voltage with ±2% tolerance (17.6–18.4 V), 45 Ω dynamic impedance at 5 mA test current, and 250 mW power dissipation on FR-5 board - used in voltage reference, overvoltage protection, and biasing circuits in portable electronics.
For engineers reviewing the BZX84B18LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance, temperature coefficient (12.6 mV/°C), leakage current (≤50 nA @ 14.4 V), and SOT-23 thermal performance under 250 mW derating.
Technical Context
This device operates as a two-terminal voltage reference diode, conducting in reverse breakdown to clamp voltage at its specified Zener level. Its tight 2% tolerance and low temperature coefficient (12.6 mV/°C) enable stable regulation across industrial temperature ranges (−65°C to +150°C).
The SOT-23 package features anode (Pin 1), no connection (Pin 2), and cathode (Pin 3), supporting automated placement and reflow soldering per JEDEC standards. Thermal resistance is 500 °C/W on FR-5 board, limiting continuous power to 250 mW at 25°C ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 18.0 V nominal, 17.6–18.4 V range at 5 mA - enables precise 18 V rail clamping or reference generation |
| Zener Impedance (ZZT) | 45 Ω max at IZT = 5 mA - ensures minimal voltage deviation under load transients |
| Power Dissipation (PD) | 250 mW on FR-5 board at 25°C - defines maximum steady-state energy handling before thermal derating |
| Reverse Leakage (IR) | ≤50 nA at 14.4 V - guarantees low quiescent current in standby or high-impedance sensing nodes |
| Temperature Coefficient | +12.6 mV/°C at 5 mA - quantifies voltage drift per degree, critical for temperature-stable references |
| Capacitance (C) | 100 pF at 0 V, 1 MHz - impacts high-frequency noise filtering and AC coupling behavior |
| ESD Rating | Class 3 (>16 kV HBM) - supports robust handling in manual assembly and field-replaceable modules |
Pinout & Package
SOT-23 (TO-236) surface-mount plastic package, 2.90 × 1.30 × 1.00 mm, void-free thermosetting case with corrosion-resistant finish, rated for 260°C soldering (10 s). Cathode indicated by polarity band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode | Forward-biased terminal; connects to lower-potential node during regulation |
| 2 | No Connection | Internally unconnected; must remain floating - no PCB trace or pad required |
| 3 | Cathode | Reverse-biased terminal; connects to regulated output or reference node |
Key Features
| Feature | Design Value |
|---|---|
| Tight Zener voltage tolerance | ±2% (17.6–18.4 V) - reduces need for post-production calibration in precision analog circuits |
| Low dynamic impedance | 45 Ω max at 5 mA - maintains regulation accuracy under varying load currents up to 20 mA |
| High ESD robustness | Class 3 (>16 kV HBM) - eliminates need for external ESD protection in handheld and USB-powered devices |
| Pb-free and RoHS compliant | Meets EU Directive 2011/65/EU - supports compliance-critical industrial and automotive supply chains |
| Optimized for automated assembly | SOT-23 footprint compatible with standard pick-and-place and reflow profiles - minimizes line changeover time |
Applications
| Portable Power Management | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Voltage clamping on 18 V DC input rails of Bluetooth headsets and smart wearables. IC Role / Device Role / Timing Role: Zener diode providing overvoltage protection and stable 18 V reference for LDO feedback networks. Use Value: Prevents damage from transient surges while maintaining <±0.36 V regulation error across −40°C to +85°C operating range. |
Use Scenario: Precision biasing of bridge amplifier inputs in factory-floor pressure transducers. IC Role / Device Role / Timing Role: Two-terminal voltage reference establishing fixed common-mode offset for instrumentation amplifiers. Use Value: Delivers 18 V reference with ≤50 nA leakage, minimizing input bias current errors in µV-level signal paths. |
| Automotive Body Control Modules | Medical Diagnostic Equipment |
Use Scenario: Regulating auxiliary 18 V supply for LIN bus transceivers in door module ECUs. IC Role / Device Role / Timing Role: Zener-based shunt regulator stabilizing local VREF for CAN/LIN interface ICs. Use Value: AEC-Q101 qualified variant available (SZBZX84B18LT1G); supports 15-year automotive lifecycle with <0.1% parametric drift. |
Use Scenario: Providing isolated 18 V reference for ADC front-end in portable ultrasound probe electronics. IC Role / Device Role / Timing Role: Low-capacitance (100 pF) Zener ensuring minimal loading on high-impedance sensor buffers. Use Value: Enables >100 dB CMRR in differential signal chains without degrading bandwidth or introducing switching noise. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84C18LT1G | Standard-tolerance (±5%) version; 16.8–19.1 V range; same SOT-23 package and 45 Ω ZZT | Acceptable where ±5% regulation suffices (e.g., non-critical power sequencing) | Select when cost sensitivity outweighs precision requirements; identical footprint and thermal profile. |
| MMSZ4702T1G | 18 V nominal, ±5% tolerance, 500 mW rating on FR-4, higher leakage (≤100 nA @ 14.4 V) | Suitable for higher-power derated designs requiring >250 mW margin | Choose for legacy designs using larger SOD-123 footprint; not drop-in due to package mismatch. |
Compared with BZX84B18LT1, BZX84C18LT1G offers lower cost but wider voltage spread, while MMSZ4702T1G provides higher power headroom at the expense of larger size and reduced precision - making BZX84B18LT1 optimal for space-constrained, high-accuracy 18 V reference needs.
Availability
BZX84B18LT1 is available at Aetrix Electronics and suitable for portable electronics, industrial sensor interfaces, and automotive body control modules requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for BZX84B18LT1 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 (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
BZX84BxxxLT1G series belongs to onsemi's precision Zener voltage regulator product line, engineered for high-density PCBs in battery-powered and safety-critical systems where tight tolerance and thermal stability are mandatory.
FAQ
What is the exact Zener voltage tolerance of BZX84B18LT1?
The BZX84B18LT1 has a tight ±2% Zener voltage tolerance, specifying 17.6 V minimum to 18.4 V maximum at 5 mA test current (IZT), as confirmed in the "BZX84BxxxL (Tight Tolerance Series)" table on page 4 of the official onsemi datasheet. This precision enables use in applications where standard ±5% Zeners like BZX84C18LT1G would introduce unacceptable regulation error.
Does BZX84B18LT1 have a no-connect pin, and how should it be handled on PCB?
Yes, BZX84B18LT1 uses Pin 2 as a no-connection terminal per the SOT-23 Style 8 pinout (page 6 of datasheet). It must remain electrically floating - no trace, pad, or via should connect to Pin 2. PCB layout must isolate this pad from all copper layers to prevent unintended parasitic coupling or solder bridging.
What is the maximum reverse leakage current for BZX84B18LT1, and at what voltage is it specified?
The maximum reverse leakage current for BZX84B18LT1 is 50 nA, measured at VR = 14.4 V (80% of nominal 18 V Zener voltage), as stated in the Electrical Characteristics table on page 4. This low leakage ensures minimal current draw in high-impedance reference or standby circuits, preserving battery life in portable devices.
Can BZX84B18LT1 be used in automotive applications?
Yes - the automotive-qualified variant SZBZX84B18LT1G is AEC-Q101 qualified and PPAP capable, sharing identical electrical specs and SOT-23 packaging with BZX84B18LT1. While BZX84B18LT1 itself is not automotive-grade, its SZ-prefix counterpart meets stringent automotive reliability and traceability requirements for body control, lighting, and infotainment modules.
What is the thermal resistance and power derating behavior of BZX84B18LT1?
BZX84B18LT1 has a junction-to-ambient thermal resistance (RJA) of 500 °C/W on FR-5 board. Its 250 mW power rating derates linearly at 2.0 mW/°C above 25°C ambient, meaning usable power drops to 200 mW at 50°C and 150 mW at 75°C - requiring careful thermal design in enclosed or high-temperature environments.
BZX84B18LT1 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- BZX84BxxxLT1
- 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)
BZX84B18LT1 FAQ
1.How can I place an order for BZX84B18LT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84B18LT1 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 BZX84B18LT1 reliable?
The price and inventory of BZX84B18LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84B18LT1 is usually 5 days.
3.What payment methods are accepted for BZX84B18LT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84B18LT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84B18LT1?
BZX84B18LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84B18LT1 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 BZX84B18LT1?
For technical support, including BZX84B18LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84B18LT1 requirements.
6.How does Aetrix verify that BZX84B18LT1 is sourced from the original manufacturer or authorized distributors?
All BZX84B18LT1 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 BZX84B18LT1 meets industry standards.
7.What is the process for return or replacement of BZX84B18LT1?
All BZX84B18LT1 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84B18LT1, 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 BZX84B18LT1 part is unused and in its original packaging.
Return procedure for BZX84B18LT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84B18LT1 Tags
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