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Nexperia USA Inc. BZX84W-B18-QX
- Part No.:
- BZX84W-B18-QX
- Manufacturer:
- Nexperia USA Inc.
- Category:
- Single Zener Diodes
- Package:
- SC-70, SOT-323
- Datasheet:
-
BZX84W-B18-QX.pdf
- Description:
- DIODE ZENER 18V 275MW SOT323
- Quantity:
- Payment:
- Shipping:
Inventory:5,757
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Product details
Overview
BZX84W-B18-QX from Nexperia is a ±2% tolerance Zener voltage regulator diode with a nominal 18 V breakdown voltage, 225 Ω differential resistance at 5 mA, and 14.4 mV/K temperature coefficient, housed in an AEC-Q101-qualified SOT323 (SC-70) package for automotive power rail stabilization.
For engineers reviewing the BZX84W-B18-QX datasheet, BZX84W-B18-QX pinout, BZX84W-B18-QX application, or BZX84W-B18-QX equivalent, this part supports precision voltage reference, overvoltage clamping, and low-power regulation in space-constrained automotive ECUs and industrial sensor interfaces where thermal stability and automotive qualification are mandatory.
Technical Context
This Zener diode operates in reverse-bias breakdown mode to maintain a stable 18 V reference across its cathode-anode terminals under regulated current conditions. Its ±2% tolerance ensures tight voltage control, while the 14.4 mV/K temperature coefficient defines predictable drift over operating temperature.
The device delivers 275 mW total power dissipation on FR4 PCB with single-sided copper, and exhibits 1.5 pF junction capacitance at 1 MHz and 0 V reverse bias - enabling use in high-frequency noise suppression and transient voltage clamping circuits without signal integrity degradation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 17.6 V to 18.4 V at IZ = 5 mA - defines precise regulation window for 18 V rail supervision |
| Tolerance | ±2% - enables tighter system-level voltage margining than ±5% variants |
| Differential Resistance (rdif) | 225 Ω max at IZ = 5 mA - determines output impedance and load regulation error |
| Temperature Coefficient (SZ) | 14.4 mV/K - quantifies voltage drift per degree Celsius rise in junction temperature |
| Reverse Current (IR) | 50 nA max at VR = 12.6 V - ensures minimal leakage during standby operation |
| Total Power Dissipation (Ptot) | 275 mW on FR4 PCB - sets maximum continuous DC or low-duty-cycle pulse power handling |
| Junction-to-Ambient Thermal Resistance (Rth(j-a)) | 455 K/W - defines temperature rise per watt under standard mounting conditions |
Pinout & Package
Package: SOT323 (SC-70), leadless surface-mount plastic package with 3 terminals, footprint dimensions per Figure 9 (reflow) and Figure 10 (wave soldering).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode (A) | Forward-biased terminal; connects to lower-potential node in regulation path |
| 2 | Not Connected (n.c.) | Internally unconnected; must remain floating - no PCB trace or pad required |
| 3 | Cathode (K) | Reverse-biased terminal; connects to higher-potential node and regulates voltage at this node |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability including HTOL, TC, HAST, and ESD testing |
| Low junction capacitance | 1.5 pF at 1 MHz and 0 V - minimizes high-frequency loading in RF-coupled protection paths |
| Stable temperature coefficient | 14.4 mV/K at 5 mA - enables predictable compensation in temperature-sensitive reference designs |
| High surge capability | 40 W non-repetitive peak reverse power at 100 µs pulse - withstands ESD and load-dump transients |
| Compact SOT323 footprint | 2.2 mm × 1.35 mm × 0.95 mm - fits dense automotive PCB layouts with minimal board area |
Applications
| Automotive Body Control Module (BCM) | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Stabilizing 18 V supply rails for LIN transceivers and microcontroller I/O buffers in door module ECUs. IC Role / Device Role / Timing Role: Zener shunt regulator maintaining reference voltage under battery voltage fluctuations and load transients. Use Value: ±2% tolerance and AEC-Q101 qualification ensure functional safety compliance and long-term stability across −40 °C to +125 °C ambient. |
Use Scenario: Providing a stable 18 V reference for analog front-end amplifiers in pressure and temperature sensor nodes. IC Role / Device Role / Timing Role: Precision voltage clamp establishing known bias point for op-amp input stages and ADC reference dividers. Use Value: 14.4 mV/K temperature coefficient allows accurate thermal drift modeling, and 225 Ω rdif limits regulation error under varying sensor load currents. |
| Automotive Infotainment Power Sequencing | Medical Diagnostic Equipment Power Monitoring |
Use Scenario: Clamping auxiliary 18 V rail during cold-crank events to prevent overvoltage damage to display drivers and audio codecs. IC Role / Device Role / Timing Role: Transient voltage suppressor absorbing short-duration surges while maintaining steady-state regulation. Use Value: 40 W non-repetitive peak power rating handles ISO 7637-2 Pulse 5a transients without failure. |
Use Scenario: Monitoring 18 V backup battery voltage in portable diagnostic devices to trigger low-battery alerts before critical shutdown. IC Role / Device Role / Timing Role: Low-leakage (50 nA) voltage reference enabling ultra-low-power wake-up circuitry. Use Value: Sub-100 nA reverse current at 70% of VZ extends battery life in always-on monitoring modes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84W-C18-Q | ±5% tolerance (16.8 V–19.1 V), higher 250 Ω rdif, same SOT323 package | Acceptable where system voltage margins exceed ±2%, e.g., non-safety-critical power monitoring | Select when cost sensitivity outweighs precision requirements and thermal drift budget permits wider VZ spread |
| MMSZ4689T1G | ±5% tolerance (17.1 V–18.9 V), 200 Ω rdif, SOD-123 package (larger footprint, higher Ptot = 500 mW) | Suitable for higher-power industrial regulators where board space allows larger package | Choose when thermal derating headroom is needed beyond 275 mW or legacy SOD-123 layout compatibility is required |
Compared with BZX84W-B18-QX, the ±5% BZX84W-C18-Q trades voltage accuracy for cost, while MMSZ4689T1G offers higher power handling in a less space-efficient package - making the BZX84W-B18-QX optimal for AEC-Q101-compliant, size-constrained 18 V regulation.
Availability
BZX84W-B18-QX is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, and medical diagnostic equipment requiring stable component supply with full AEC-Q101 traceability and long-term lifecycle support.
Supply support for BZX84W-B18-QX 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
Nexperia is a global semiconductor expert delivering high-performance, reliable discrete, logic, and MOSFET devices with focus on efficiency, miniaturization, and automotive-grade quality.
The BZX84W-Q series belongs to Nexperia's AEC-Q101-qualified Zener diode portfolio, engineered specifically for robust voltage regulation and transient suppression in automotive power systems and harsh-environment industrial controls.
FAQ
What is the maximum continuous reverse current for BZX84W-B18-QX at 25 °C?
The device has no specified maximum continuous reverse current; instead, it is rated by power dissipation. At 25 °C ambient, the 275 mW limit corresponds to a maximum Zener current of approximately 15.3 mA (275 mW ÷ 18 V). Operation above this requires thermal derating per the Rth(j-a) = 455 K/W specification.
Is Pin 2 electrically connected internally?
No - Pin 2 is explicitly designated "n.c." (not connected) in the official Nexperia datasheet. It is an isolated metallurgical terminal with no internal bond wire or silicon connection, and must remain unconnected on the PCB to avoid mechanical stress or unintended coupling.
How does the 14.4 mV/K temperature coefficient impact regulation accuracy over temperature?
At a 100 °C junction temperature rise (e.g., from 25 °C to 125 °C), the Zener voltage shifts by +1.44 V (14.4 mV/K × 100 K), resulting in a final VZ of ~19.44 V. This shift is linear and predictable, enabling compensation in closed-loop systems or acceptable within ±8% total variation for many automotive monitoring functions.
Can BZX84W-B18-QX be used in place of a 1N4746A?
No - although both are 18 V Zeners, the 1N4746A uses DO-41 through-hole packaging (1 W Ptot, ±5%), while BZX84W-B18-QX is SOT323 surface-mount (275 mW, ±2%). Direct replacement requires verifying board layout, thermal design, and surge handling; the smaller package cannot dissipate equivalent power without significant derating.
BZX84W-B18-QX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Nexperia USA Inc.
- Series:
- BZX84W-Q
- Package/Case:
- SC-70, SOT-323
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 18 V
- Tolerance:
- ±2.22%
- Power - Max:
- 275 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:
- 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-323
BZX84W-B18-QX FAQ
1.How can I place an order for BZX84W-B18-QX through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84W-B18-QX 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 BZX84W-B18-QX reliable?
The price and inventory of BZX84W-B18-QX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84W-B18-QX is usually 5 days.
3.What payment methods are accepted for BZX84W-B18-QX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84W-B18-QX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84W-B18-QX?
BZX84W-B18-QX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84W-B18-QX 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 BZX84W-B18-QX?
For technical support, including BZX84W-B18-QX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84W-B18-QX requirements.
6.How does Aetrix verify that BZX84W-B18-QX is sourced from the original manufacturer or authorized distributors?
All BZX84W-B18-QX 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 BZX84W-B18-QX meets industry standards.
7.What is the process for return or replacement of BZX84W-B18-QX?
All BZX84W-B18-QX units undergo pre-shipment inspection (PSI). If there is an issue with BZX84W-B18-QX, 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 BZX84W-B18-QX part is unused and in its original packaging.
Return procedure for BZX84W-B18-QX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84W-B18-QX Tags
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