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Diodes Incorporated SMF4L18AQ-7
- Part No.:
- SMF4L18AQ-7
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-219AA
- Datasheet:
-
SMF4L18AQ-7.pdf
- Description:
- TRANSIENT VOLTAGE SUPPRESSOR PP
- Quantity:
- Payment:
- Shipping:
Inventory:7,413
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Product details
Overview
SMF4L18AQ from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for automotive-grade overvoltage protection in power rails and signal lines. It features a 18V working peak reverse voltage (VRWM), 20–22.1V breakdown voltage (VBR), 29.2V maximum clamping voltage (VC) at 13.7A surge current, and AEC-Q101 qualification for under-hood and battery-contact applications.
For engineers reviewing the SMF4L18AQ datasheet, SMF4L18AQ pinout, SMF4L18AQ application, or SMF4L18AQ equivalent, key selection criteria include clamping performance at 10/1000µs waveform, IEC 61000-4-2 ±30kV ESD robustness, DO-219AA package thermal resistance (RθJA = 96°C/W), and unidirectional polarity marking with cathode band.
Technical Context
This TVS operates as a fast-acting shunt clamp during transients, triggering when reverse voltage exceeds VBR (20–22.1V) to divert surge energy away from protected circuitry. Its sub-1ns response time ensures suppression before sensitive components experience overstress.
Designed for automotive environments, it sustains 40A peak forward surge current (IFSM), handles 1.0W steady-state dissipation on FR-4 PCB, and maintains operation from –55°C to +175°C - matching under-hood thermal requirements without derating up to +125°C ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; sets safe margin above 12V automotive nominal rail. |
| VBR (min/max) | 20 / 22.1 V - Breakdown occurs within this range at 1mA test current; defines precise turn-on threshold for predictable protection timing. |
| VC @ IPP | 29.2 V at 13.7 A - Clamping voltage during 10/1000µs surge; limits downstream voltage stress to ≤29.2V under worst-case 400W transient. |
| PPK | 400 W - Peak pulse power rating per 10/1000µs waveform; determines survivability against ISO 7637-2 Pulse 1/2/5a surges. |
| IR @ VRWM | 0.5 µA - Reverse leakage at 18V; negligible power loss and minimal impact on high-impedance sensing circuits. |
| ESD Rating | ±30 kV air / ±30 kV contact per IEC 61000-4-2 - Enables direct interface with exposed connectors without external ESD staging. |
| Package | DO-219AA - Low-profile (0.6mm typical lead length), thermally efficient surface-mount package with RθJC = 18°C/W for PCB heat sinking. |
Pinout & Package
Package: DO-219AA - molded green plastic case, matte tin-plated copper alloy leadframe, 0.016g weight, UL 94V-0 rated, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction path | Connected to protected line (e.g., 12V rail); conducts during positive surges only in unidirectional configuration. |
| Cathode (marked with band) | Clamping reference node | Connected to ground or lower-potential rail; establishes reverse-bias trigger point and provides low-impedance surge return path. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive use including temperature cycling, HTRB, and ESD stress - enables PPAP submission and IATF 16949 traceability. |
| 400W 10/1000µs pulse rating | Withstands ISO 7637-2 Pulse 5a (load dump) events up to 400W without degradation, supporting 24V commercial vehicle systems. |
| Sub-1ns response time | Activates within <1ns from 0V to VBR - faster than most microcontroller I/O response, ensuring IC-level protection prior to logic upset. |
| Halogen- and antimony-free "Green" construction | Meets RoHS 3 (2015/863/EU) with Br+Cl <1500ppm and Sb <1000ppm - supports OEM environmental compliance and end-of-life recycling mandates. |
| Low RθJA (96°C/W) | Enables 1.0W steady-state dissipation on standard 1"×1" FR-4 board - eliminates need for thermal vias or heatsinks in space-constrained modules. |
Applications
| Automotive Power Rail Protection | Battery Contact ESD Suppression |
|---|---|
|
Use Scenario: Protecting 12V supply inputs of body control modules (BCM), infotainment head units, and ADAS domain controllers from load dump and jump-start transients. IC Role / Device Role / Timing Role: Shunt-clamp TVS placed between VBAT and GND, triggered within 1ns to clamp voltage to ≤29.2V during 400W surges. Use Value: Prevents latch-up or permanent damage to PMICs and microcontrollers by limiting transient overvoltage below their absolute maximum ratings. |
Use Scenario: Guarding exposed battery terminal interfaces (e.g., OBD-II ports, jump-start terminals) against human-body-model (HBM) and contact ESD events. IC Role / Device Role / Timing Role: Unidirectional TVS connected anode-to-terminal, cathode-to-chassis ground, providing ±30kV IEC 61000-4-2 immunity. Use Value: Eliminates need for discrete RC filters or multi-stage protection, reducing BOM count while maintaining full automotive ESD compliance. |
| Industrial Sensor Interface Protection | USB-C Power Delivery Line Clamp |
|
Use Scenario: Safeguarding analog sensor inputs (e.g., pressure, temperature) in industrial PLC I/O modules exposed to inductive switching noise on 24V DC lines. IC Role / Device Role / Timing Role: Low-leakage (0.5µA) TVS placed across sensor supply and return, clamping transients before they couple into precision ADC front-ends. Use Value: Maintains signal integrity by preventing offset drift or saturation caused by transient-induced bias shifts in op-amp conditioning stages. |
Use Scenario: Clamping VBUS lines in USB-C PD adapters and automotive charging ports where 20V-rated PD profiles require robust 18–20V standoff capability. IC Role / Device Role / Timing Role: Unidirectional TVS installed between VBUS and GND, leveraging 18V VRWM to avoid conduction during normal 20V PD operation while clamping surges. Use Value: Enables single-device protection for both 9V/15V/20V PD profiles without compromising efficiency or requiring voltage-selectable designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Same DO-214AC package; higher RθJA (110°C/W); 300W PPK rating; 32.4V VC @ 12.3A. | Larger footprint; lower surge handling; less suitable for compact automotive modules with tight thermal budgets. | Prefer SMF4L18AQ where board space and thermal performance are constrained, especially in AEC-Q101–required designs. |
| 1.5SMC18A | DO-214AB package; 1500W PPK; 29.2V VC @ 51.7A; higher capacitance (~150pF). | Higher surge capacity but larger size and greater parasitic capacitance - risks signal integrity on high-speed lines. | Choose SMF4L18AQ for space-limited, high-frequency, or automotive-critical applications where low capacitance (<50pF) and AEC-Q101 are mandatory. |
Compared with SMAJ18A and 1.5SMC18A, SMF4L18AQ delivers superior thermal efficiency (96°C/W vs. ≥110°C/W), smaller DO-219AA footprint, and guaranteed AEC-Q101 qualification - making it optimal for next-gen automotive ECUs and miniaturized industrial power interfaces.
Availability
SMF4L18AQ is available at Aetrix Electronics and suitable for automotive power management, battery-contact ESD protection, and industrial sensor interface applications requiring stable component supply and long-term lifecycle support.
Supply support for SMF4L18AQ 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 protection, power management, and signal integrity solutions for automotive, industrial, and consumer markets.
The SMF4L series belongs to Diodes' AEC-Q101–qualified TVS portfolio, engineered specifically for automotive transient suppression with emphasis on low clamping voltage, ultrafast response, and green packaging compliance.
FAQ
What is the polarity configuration of SMF4L18AQ?
SMF4L18AQ is a unidirectional TVS diode, indicated by a cathode band on the DO-219AA package. It conducts only during reverse-voltage transients - i.e., when the cathode is more positive than the anode - and blocks forward current like a standard rectifier diode. This configuration is ideal for DC power rail protection where polarity is fixed.
Does SMF4L18AQ require derating at elevated ambient temperatures?
Yes - its peak pulse power must be linearly derated above +25°C ambient, per Figure 1 in DS43393. At +85°C, it retains ~75% of rated 400W (≈300W); at +125°C, ~50% (200W). Steady-state power also derates per Figure 3: 1.0W at +25°C drops to ~0.5W at +100°C on standard FR-4 layout.
How does SMF4L18AQ compare to bi-directional variants like SMF4L18CAQ?
SMF4L18AQ clamps only reverse transients (anode-to-ground), while SMF4L18CAQ clamps both polarities (anode/cathode symmetric). The unidirectional version offers lower leakage (0.5µA vs. 1.0µA for bi-directional), tighter VBR tolerance, and slightly lower VC - making it preferred for DC power rails where polarity is known and ESD directionality is controlled.
Is SMF4L18AQ compatible with lead-free reflow soldering processes?
Yes - it features matte tin finish on annealed copper alloy leadframe and is qualified for Pb-free reflow per JEDEC J-STD-020. The DO-219AA package withstands peak temperatures up to 260°C for 30 seconds, meeting IPC/JEDEC Class 3 standards. Moisture sensitivity level is rated Level 1, eliminating bake requirements prior to assembly.
SMF4L18AQ-7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- DO-219AA
- Series:
- SMF4L
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 13.7A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-219AA
SMF4L18AQ-7 FAQ
1.How can I place an order for SMF4L18AQ-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF4L18AQ-7 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 SMF4L18AQ-7 reliable?
The price and inventory of SMF4L18AQ-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF4L18AQ-7 is usually 5 days.
3.What payment methods are accepted for SMF4L18AQ-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF4L18AQ-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF4L18AQ-7?
SMF4L18AQ-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF4L18AQ-7 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 SMF4L18AQ-7?
For technical support, including SMF4L18AQ-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF4L18AQ-7 requirements.
6.How does Aetrix verify that SMF4L18AQ-7 is sourced from the original manufacturer or authorized distributors?
All SMF4L18AQ-7 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 SMF4L18AQ-7 meets industry standards.
7.What is the process for return or replacement of SMF4L18AQ-7?
All SMF4L18AQ-7 units undergo pre-shipment inspection (PSI). If there is an issue with SMF4L18AQ-7, 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 SMF4L18AQ-7 part is unused and in its original packaging.
Return procedure for SMF4L18AQ-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF4L18AQ-7 Tags
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