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Diodes Incorporated SMF4L40A-7
- Part No.:
- SMF4L40A-7
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-219AA
- Datasheet:
-
SMF4L40A-7.pdf
- Description:
- TRANSIENT VOLTAGE SUPPRESSOR PP
- Quantity:
- Payment:
- Shipping:
Inventory:7,973
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Product details
Overview
SMF4L40A-7 from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for overvoltage protection in DC power lines and signal interfaces. It features a 40V working peak reverse voltage (VRWM), 44.4V minimum breakdown voltage (VBR), 64.5V maximum clamping voltage (VC) at 6.2A surge current, and IEC61000-4-2 ±30kV ESD immunity - deployed in automotive battery contacts and industrial power management systems.
For engineers reviewing the SMF4L40A-7 datasheet, SMF4L40A-7 pinout, SMF4L40A-7 application, or SMF4L40A-7 equivalent, this part is selected for robust 400W transient suppression in space-constrained DO-219AA packages where fast response (<1.0ns), low leakage (<0.5µA), and AEC-Q-compliant reliability are required.
Technical Context
This TVS operates as a unidirectional avalanche clamp, triggered when reverse voltage exceeds 44.4V (min) and fully clamping to ≤64.5V at 6.2A peak pulse current under 10/1000µs waveform. Its junction capacitance is not specified in the datasheet, but its sub-1ns response ensures protection of high-speed interfaces without signal distortion.
Thermally, it delivers 1.0W steady-state dissipation with 96°C/W junction-to-ambient thermal resistance on standard FR-4 PCB layout, and supports operation from –55°C to +175°C - enabling use in under-hood automotive environments and industrial power supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400W (10/1000µs waveform): sustains high-energy transients like ISO 7637-2 load dump spikes |
| Working Peak Reverse Voltage | 40V: sets maximum continuous DC line voltage before conduction begins |
| Breakdown Voltage (Min) | 44.4V @ 1mA: defines precise avalanche onset threshold for predictable clamping |
| Clamping Voltage (Max) | 64.5V @ 6.2A: limits protected circuit voltage during worst-case surge |
| ESD Rating | ±30kV contact & air per IEC61000-4-2: meets stringent system-level ESD immunity requirements |
| Leakage Current | <0.5µA @ 40V: minimizes standby power loss in always-on battery circuits |
| Response Time | <1.0ns (unidirectional): reacts faster than most microcontrollers can be damaged by EFT |
Pinout & Package
Package: DO-219AA - ultra-compact surface-mount plastic package (1.90mm × 2.80mm × 3.80mm), RoHS-compliant, halogen-free, moisture sensitivity level 1, with matte tin-plated copper alloy leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or lower-potential rail; completes clamping path during overvoltage |
| Cathode | High-side transient input | Connected to protected line (e.g., 40V supply rail); cathode band denotes polarity |
Key Features
| Feature | Design Value |
|---|---|
| 400W peak pulse rating | Enables single-device protection against ISO 7637-2 Pulse 5a (load dump) in 12V automotive systems |
| Unidirectional configuration | Blocks reverse conduction while clamping positive transients - ideal for DC supply rails |
| ±30kV IEC61000-4-2 ESD immunity | Eliminates need for additional ESD stages in USB, CAN, or sensor interface ports |
| DO-219AA footprint | Reduces board area by ~40% vs. SMA/SMB packages while maintaining thermal performance |
| AEC-Q200 readiness | Manufactured in IATF 16949 facilities; Q-suffix variants available for full automotive qualification |
Applications
| Automotive Battery Protection | Industrial DC Power Rail |
|---|---|
Use Scenario: Protecting 12V/24V battery-fed ECUs from load dump and jump-start surges. IC Role / Device Role / Timing Role: Unidirectional TVS clamping device placed directly at connector entry point. Use Value: Limits transient voltage to ≤64.5V, preventing damage to downstream PMICs and microcontrollers rated for 65V max. | Use Scenario: Safeguarding programmable logic controller (PLC) 24V DC input modules against field-wiring induced surges. IC Role / Device Role / Timing Role: Primary overvoltage clamp on field-side power entry before filtering and regulation. Use Value: Withstands repeated 400W pulses without degradation, ensuring long-term reliability in factory automation environments. |
| USB Type-C VBUS Line | Smart Meter Power Input |
Use Scenario: ESD and surge protection on USB-C VBUS line (5–20V PD negotiation range). IC Role / Device Role / Timing Role: Secondary protection stage after primary common-mode choke, handling differential surges. Use Value: Sub-1ns response prevents latch-up in USB PD controllers; <0.5µA leakage avoids battery drain in portable devices. | Use Scenario: Protecting revenue-grade smart meter power inputs exposed to utility grid transients. IC Role / Device Role / Timing Role: First-line transient suppressor on AC-DC converter input or DC backup rail. Use Value: Stable 40V VRWM aligns with 36V nominal backup battery systems; 175°C max operating temperature supports sealed meter enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ40A | Same 40V VRWM, but SMA package (larger footprint, higher RθJA = 125°C/W) | Less suitable for dense automotive PCBs; lower power density (400W same, but derates faster above 25°C) | Select if legacy SMA layout exists and thermal margin >15°C is available |
| SMF4L40CA | Bidirectional variant; identical VRWM, VBR, VC, and package - differs only in symmetry | Required for AC-coupled or bidirectional signal lines (e.g., RS-485, CAN FD), not DC rails | Choose only when protecting symmetric signals; avoid for unidirectional power rails due to unnecessary reverse conduction path |
Compared with SMAJ40A and SMF4L40CA, SMF4L40A-7 offers superior board-space efficiency and thermal performance in unidirectional DC protection roles, while SMF4L40CA provides identical clamping for bidirectional use cases - making SMF4L40A-7 the optimal choice for compact, high-reliability 40V rail protection.
Availability
SMF4L40A-7 is available at Aetrix Electronics and suitable for automotive battery protection, industrial DC power rail hardening, and USB Type-C VBUS line protection requiring stable component supply across production lifecycles.
Supply support for SMF4L40A-7 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.
The SMF4L series belongs to Diodes' high-reliability transient suppression product line, engineered specifically for space-constrained, high-surge industrial and automotive applications demanding AEC-Q200 alignment and green material compliance.
FAQ
What is the maximum clamping voltage of SMF4L40A-7 at rated surge current?
The maximum clamping voltage (VC) is 64.5V at 6.2A peak pulse current under the standardized 10/1000µs waveform. This value is guaranteed across temperature and lifetime, ensuring consistent protection margin for downstream 65V-rated components such as automotive PMICs and industrial regulators.
Is SMF4L40A-7 suitable for automotive under-hood applications?
Yes - it operates from –55°C to +175°C, is manufactured in IATF 16949-certified facilities, and has documented performance under ISO 7637-2 load dump conditions. While the base part is not AEC-Q200 qualified, the Q-suffix variant (SMF4L40AQ-7) is fully qualified and drop-in compatible for critical under-hood designs.
How does the DO-219AA package compare thermally to SMA or SMB packages?
DO-219AA offers 96°C/W junction-to-ambient thermal resistance on standard FR-4, versus 125°C/W for SMAJ40A (SMA) and 110°C/W for SMBJ40A (SMB). Its smaller footprint does not compromise thermal performance - enabled by optimized die attach and low-RθJC (14°C/W) design - making it ideal for high-density automotive modules.
Can SMF4L40A-7 replace older SMAJ40A parts in existing designs?
Yes, with layout adaptation: both share identical electrical specs (VRWM, VBR, VC, IPP), but DO-219AA requires updated land pattern (1.90mm × 2.80mm vs. SMA's 4.5mm × 2.7mm). Thermal and surge performance improves, and solder reflow profiles remain compatible - no changes to schematic or system-level validation are needed beyond mechanical verification.
SMF4L40A-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):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 64.5V
- Current - Peak Pulse (10/1000µs):
- 6.2A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-219AA
SMF4L40A-7 FAQ
1.How can I place an order for SMF4L40A-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF4L40A-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 SMF4L40A-7 reliable?
The price and inventory of SMF4L40A-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF4L40A-7 is usually 5 days.
3.What payment methods are accepted for SMF4L40A-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF4L40A-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF4L40A-7?
SMF4L40A-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF4L40A-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 SMF4L40A-7?
For technical support, including SMF4L40A-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF4L40A-7 requirements.
6.How does Aetrix verify that SMF4L40A-7 is sourced from the original manufacturer or authorized distributors?
All SMF4L40A-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 SMF4L40A-7 meets industry standards.
7.What is the process for return or replacement of SMF4L40A-7?
All SMF4L40A-7 units undergo pre-shipment inspection (PSI). If there is an issue with SMF4L40A-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 SMF4L40A-7 part is unused and in its original packaging.
Return procedure for SMF4L40A-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF4L40A-7 Tags
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ESD9B5.0ST5G
onsemi
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Diodes Incorporated
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Diodes Incorporated
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Diodes Incorporated
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Diodes Incorporated
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onsemi
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Diodes Incorporated
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Diodes Incorporated
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Diodes Incorporated
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