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Diodes Incorporated BZX84B18Q-7-F
- Part No.:
- BZX84B18Q-7-F
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84B18Q-7-F.pdf
- Description:
- DIODE ZENER 18V 300MW SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:3,607
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Product details
Overview
BZX84B18Q-7-F from Diodes Incorporated is an AEC-Q101-qualified surface-mount precision Zener diode with nominal 18 V zener voltage (±2% tolerance), 350 mW power dissipation, and 45 Ω dynamic impedance at 5 mA test current. It operates across –65 °C to +150 °C and is used for voltage regulation and overvoltage protection in automotive body control modules.
For engineers reviewing the BZX84B18Q-7-F datasheet, BZX84B18Q-7-F pinout, BZX84B18Q-7-F application, or BZX84B18Q-7-F equivalent, key selection criteria include its ±2% VZ tolerance, low 0.1 µA reverse leakage at 12.6 V, and SOT23 package compatibility with automated assembly and high-reliability automotive environments.
Technical Context
This Zener diode delivers stable reference voltage under reverse-biased operation with a nominal breakdown voltage of 18 V at 5 mA test current (IZT). Its temperature coefficient of +12.4 mV/°C ensures predictable drift behavior above 10 V, and it maintains ≤0.1 µA reverse current at VR = 12.6 V.
The device is rated for 350 mW power dissipation under ambient-temperature terminal conditions and exhibits 357 °C/W thermal resistance (junction-to-ambient). Its SOT23 package supports reflow soldering per J-STD-020 Level 1 moisture sensitivity and meets AEC-Q101 stress testing requirements for automotive use.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 18 V nominal, 17.6–18.4 V range at 5 mA - enables precise 18 V rail clamping or reference generation |
| Tolerance | ±2% - reduces calibration overhead in voltage-sensing circuits |
| Power Dissipation | 350 mW - supports sustained regulation in compact automotive PCB layouts without forced cooling |
| Zener Impedance (ZZT) | 45 Ω at 5 mA - ensures minimal output voltage variation under load transients |
| Reverse Leakage (IR) | 0.1 µA at 12.6 V - minimizes quiescent current in always-on monitoring circuits |
| Temperature Coefficient | +12.4 mV/°C - provides known, linear VZ drift for compensated designs above 10 V |
| Package | SOT23 - enables high-density placement and compatibility with standard pick-and-place equipment |
Pinout & Package
Package: SOT23 - three-terminal surface-mount plastic case with matte tin-plated Alloy 42 leadframe; polarity marked by cathode band on top surface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Forward conduction terminal | Connected to lower-potential node during Zener operation; required for proper biasing in shunt regulator topology |
| Cathode (Pin 2) | Zener breakdown terminal | Connected to regulated voltage rail; carries reverse current during clamping or reference operation |
| NC / Heat Sink (Pin 3) | Non-connected / thermal path | No internal connection; serves as mechanical anchor and minor thermal conduction path to PCB copper |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD robustness |
| ±2% VZ tolerance | Reduces need for post-production trimming in voltage-reference applications |
| Lead-free & halogen-free "Green" construction | Complies with RoHS 3 (2015/863/EU) and automotive ELV directive requirements |
| SOT23 footprint | Enables drop-in replacement in legacy 3-pin regulator designs and supports automated optical inspection (AOI) |
| Level 1 moisture sensitivity | Eliminates bake requirement prior to reflow, reducing manufacturing cycle time and cost |
Applications
| Automotive Body Control Module (BCM) | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Regulating 18 V supply rail for microcontroller I/O buffers and CAN transceiver biasing. IC Role / Device Role: Shunt voltage reference and overvoltage clamp protecting downstream logic inputs. Use Value: Maintains stable 18 V despite battery transients up to 24 V, leveraging ±2% tolerance and 350 mW dissipation. |
Use Scenario: Providing precision 18 V reference for 16-bit ADC front-end amplifiers in pressure transducers. IC Role / Device Role: Low-drift voltage reference source with known +12.4 mV/°C TC for software compensation. Use Value: Enables <1 LSB error over –40 °C to +125 °C operating range using measured TC data. |
| LED Driver Current Sense Protection | Power Supply Feedback Loop Clamp |
Use Scenario: Clamping feedback node voltage in constant-current LED driver ICs to prevent runaway during open-circuit faults. IC Role / Device Role: Fast-acting overvoltage limiter tied to driver IC's sense input pin. Use Value: Limits fault voltage to 18.4 V max, preventing IC latch-up while drawing only 0.1 µA standby current. |
Use Scenario: Stabilizing optocoupler-based feedback voltage in isolated DC-DC converters. IC Role / Device Role: Secondary-side Zener reference that sets upper bound on feedback signal swing. Use Value: Ensures consistent regulation margin across line/load variations due to 45 Ω ZZT and tight VZ distribution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMSZ4689-TP | 18 V nominal, ±5% tolerance, 500 mW rating, SOD-123 package | Higher power but looser tolerance and larger footprint; not AEC-Q101 qualified | Select when higher surge energy handling is needed and automotive qualification is unnecessary |
| BZX84-C18 | 18 V nominal, ±5% tolerance, 350 mW, same SOT23 package, commercial grade only | Lacks AEC-Q101 qualification and tighter ±2% tolerance; lower cost for non-automotive use | Select for industrial or consumer applications where extended temperature range and automotive reliability are not required |
Compared with MMSZ4689-TP and BZX84-C18, BZX84B18Q-7-F uniquely combines AEC-Q101 qualification, ±2% VZ tolerance, and SOT23 compatibility-making it the only choice for space-constrained automotive voltage reference designs requiring production-level reliability assurance.
Availability
BZX84B18Q-7-F is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, and LED driver protection requiring stable component supply and full traceability.
Supply support for BZX84B18Q-7-F 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for automotive, industrial, and computing markets.
The BZX84B series belongs to Diodes' precision Zener portfolio, engineered specifically for AEC-Q101-compliant voltage regulation and reference applications in harsh-environment automotive ECUs and industrial controls.
FAQ
What is the maximum reverse voltage (VR) this Zener can block before breakdown?
The BZX84B18Q-7-F has a specified reverse breakdown voltage of 18 V (nominal) with a guaranteed range of 17.6 V to 18.4 V at 5 mA test current. Below 12.6 V, reverse leakage remains ≤0.1 µA - meaning it blocks effectively up to that threshold. True blocking capability ends at the knee of the Zener curve, not at a fixed "non-breakdown" limit.
Is this part suitable for use in a 12 V automotive system with load-dump transients?
Yes - the device's 18 V nominal Zener voltage provides headroom above typical 12 V nominal rails and can clamp transient spikes up to 24 V. Its 350 mW rating allows brief energy absorption during ISO 7637-2 Pulse 5a events when paired with appropriate series impedance, and AEC-Q101 qualification confirms robustness under automotive thermal and vibration stress.
How does the +12.4 mV/°C temperature coefficient affect circuit accuracy?
The +12.4 mV/°C coefficient means VZ increases by ~12.4 mV per degree Celsius rise above 25 °C. Over a –40 °C to +125 °C range, this produces ~2.05 V total drift. For high-accuracy references, this must be compensated in firmware or hardware - e.g., using a matched NTC thermistor network or digital lookup table calibrated against measured TC data.
Can BZX84B18Q-7-F replace BZX84-C18 in an existing design?
Electrically, yes - both share identical SOT23 pinout, 18 V nominal VZ, and 350 mW rating. However, BZX84B18Q-7-F adds AEC-Q101 qualification, ±2% tolerance (vs. ±5%), and automotive-grade marking/traceability. Replacement requires validation of thermal performance under automotive temperature cycling and review of qualification documentation for safety-critical systems.
BZX84B18Q-7-F Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 18 V
- Tolerance:
- ±2%
- Power - Max:
- 300 mW
- Impedance (Max) (Zzt):
- 45 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 12.6 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
BZX84B18Q-7-F FAQ
1.How can I place an order for BZX84B18Q-7-F through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84B18Q-7-F 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 BZX84B18Q-7-F reliable?
The price and inventory of BZX84B18Q-7-F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84B18Q-7-F is usually 5 days.
3.What payment methods are accepted for BZX84B18Q-7-F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84B18Q-7-F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84B18Q-7-F?
BZX84B18Q-7-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84B18Q-7-F 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 BZX84B18Q-7-F?
For technical support, including BZX84B18Q-7-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84B18Q-7-F requirements.
6.How does Aetrix verify that BZX84B18Q-7-F is sourced from the original manufacturer or authorized distributors?
All BZX84B18Q-7-F 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 BZX84B18Q-7-F meets industry standards.
7.What is the process for return or replacement of BZX84B18Q-7-F?
All BZX84B18Q-7-F units undergo pre-shipment inspection (PSI). If there is an issue with BZX84B18Q-7-F, 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 BZX84B18Q-7-F part is unused and in its original packaging.
Return procedure for BZX84B18Q-7-F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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