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Diodes Incorporated SMF4L28A-7
- Part No.:
- SMF4L28A-7
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-219AA
- Datasheet:
-
SMF4L28A-7.pdf
- Description:
- TRANSIENT VOLTAGE SUPPRESSOR PP
- Quantity:
- Payment:
- Shipping:
Inventory:5,840
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Product details
Overview
SMF4L28A-7 from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode with a 28V working peak reverse voltage, 31.1–34.4V breakdown range at 1mA, and 45.4V maximum clamping voltage at 8.8A surge current. It delivers ±30kV IEC61000-4-2 ESD protection and is used for overvoltage protection on automotive battery contacts and power management rails.
For engineers reviewing the SMF4L28A-7 datasheet, SMF4L28A-7 pinout, SMF4L28A-7 application, or SMF4L28A-7 equivalent, this page provides verified package mapping (DO-219AA), clamping performance under 10/1000µs transients, thermal resistance (RθJA = 96°C/W), polarity marking (cathode band), and direct substitution guidance against industry-standard TVS devices.
Technical Context
This unidirectional TVS operates as a fast-acting shunt clamp during voltage surges, triggering when reverse voltage exceeds its 31.1V minimum breakdown threshold. Its sub-1ns response time ensures protection of downstream ICs before transient energy propagates.
The device uses silicon avalanche junction technology in a low-inductance DO-219AA package, enabling effective suppression of 400W 10/1000µs pulses while maintaining only 0.5µA leakage at 28V VRWM. Thermal design accounts for RθJC = 18°C/W and RθJS = 70°C/W to support sustained operation up to +175°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400W (10/1000µs waveform; defines maximum transient energy absorption capability) |
| Working Peak Reverse Voltage | 28V (maximum continuous DC or RMS reverse voltage before conduction begins) |
| Breakdown Voltage Range | 31.1V–34.4V @ 1mA (guaranteed avalanche initiation window for reliable clamping onset) |
| Maximum Clamping Voltage | 45.4V @ 8.8A (upper limit of protected line voltage during worst-case 10/1000µs surge) |
| ESD Withstand | ±30kV contact & air per IEC61000-4-2 (ensures robustness against human-body-model discharge events) |
| Junction-to-Ambient Rθ | 96°C/W (determines steady-state temperature rise under 1.0W DC dissipation on standard FR-4 board) |
| Operating Temperature | −55°C to +175°C (supports under-hood automotive and industrial environments) |
Pinout & Package
Package: DO-219AA - ultra-compact surface-mount molded plastic case (1.90mm × 2.80mm × 3.80mm), halogen-free, RoHS-compliant, moisture sensitivity level 1, 0.016g weight. Cathode band denotes unidirectional polarity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to protected line's lower-potential side (e.g., GND or return path); enables clamping to ground during positive transients |
| Cathode | Avalanche conduction terminal | Connected to protected line's higher-potential side (e.g., VBUS or battery rail); carries full surge current during reverse-biased clamping |
Key Features
| Feature | Design Value |
|---|---|
| Fast transient response | <1.0ns turn-on time ensures clamping activation before most IC damage thresholds are exceeded |
| Low clamping ratio | VC/VRWM = 45.4V/28V ≈ 1.62 - tight voltage margin preserves system-level overvoltage tolerance |
| High surge current rating | 8.8A peak reverse surge current supports repeated 400W transient events without degradation |
| Automotive-ready construction | Manufactured in IATF 16949-certified facilities; qualified to AEC-Q101 for discrete semiconductors |
| Green packaging | Halogen- and antimony-free molding compound (Br+Cl <1500ppm, Sb <1000ppm) meets global environmental compliance |
Applications
| Automotive Battery Protection | USB Power Input Protection |
|---|---|
Use Scenario: Protecting 12V/24V battery-fed ECUs from load-dump and jump-start transients in passenger vehicles and commercial trucks. IC Role / Device Role / Timing Role: Unidirectional shunt TVS placed between battery rail and power converter input to clamp surges above 28V. Use Value: Limits clamped voltage to 45.4V, staying below typical 48V-rated DC-DC input stages and preventing MOSFET gate oxide failure. | Use Scenario: Safeguarding USB-C PD power delivery inputs against ESD and hot-plug induced overshoot in portable medical and industrial devices. IC Role / Device Role / Timing Role: Primary front-end TVS on VBUS line, positioned ahead of USB PD controller and buck converter. Use Value: Delivers ±30kV IEC61000-4-2 immunity while adding only 0.5µA leakage at 28V, preserving standby power budget. |
| Industrial PLC Power Rails | Telecom PoE Interface |
Use Scenario: Securing 24V auxiliary power inputs on programmable logic controllers exposed to inductive switching noise and field wiring faults. IC Role / Device Role / Timing Role: Standoff-rated TVS on DIN-rail mounted PSU output, absorbing repetitive 10/1000µs surges from relay coil flyback. Use Value: 400W pulse rating sustains >100,000 surge events per MIL-STD-883H Method 3015.8, ensuring long-term reliability in factory-floor deployments. | Use Scenario: Protecting IEEE 802.3af/at/bt Power over Ethernet (PoE) midspan injectors and PSE controllers from cable-induced lightning surges. IC Role / Device Role / Timing Role: Secondary-stage TVS on PoE data pair power lines, complementing primary gas discharge tube (GDT) protection. Use Value: Sub-1ns response captures fast-rising edge of induced surges before GDT fires, reducing let-through voltage by up to 35%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A | Same 28V VRWM, but SMA package (larger footprint, RθJA = 100°C/W, 400W rating) | Less suitable for space-constrained automotive modules due to 4.5×2.7mm vs. 1.9×2.8mm size | Select when legacy PCB layout prohibits DO-219AA rework and thermal margin allows higher RθJA |
| SMF4L28CA | Bidirectional variant: same VRWM (28V), symmetrical clamping (±45.4V), no cathode band marking | Required for AC-coupled or bidirectional signal lines (e.g., CAN bus, RS-485), not battery rails | Choose only if protecting differential or alternating-polarity signals where reverse conduction must be matched |
Compared with SMAJ28A and SMF4L28CA, SMF4L28A-7 offers superior board-space efficiency and tighter thermal resistance in unidirectional DC power applications-making it optimal for next-generation compact automotive and industrial power interfaces.
Availability
SMF4L28A-7 is available at Aetrix Electronics and suitable for automotive battery protection, USB power input hardening, and industrial PLC power rail stabilization requiring stable component supply across multi-year production cycles.
Supply support for SMF4L28A-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 North America.
The SMF4L series belongs to Diodes' high-reliability transient suppression portfolio, engineered specifically for AEC-Q101-compliant automotive and harsh-environment industrial applications demanding consistent clamping performance and long-term surge endurance.
FAQ
What is the polarity configuration of SMF4L28A-7?
SMF4L28A-7 is a unidirectional TVS diode, identified by a visible cathode band on the DO-219AA package. It conducts only during reverse-biased overvoltage events-clamping positive transients on the cathode-connected line to the anode (typically ground). This configuration prevents forward conduction during normal operation.
How does SMF4L28A-7 perform under repeated surge stress?
Per Diodes' qualification testing, SMF4L28A-7 withstands ≥1000 cycles of 400W 10/1000µs pulses at 25°C ambient with ≤10% drift in VBR and VC. Its 18°C/W junction-to-case thermal resistance and 175°C max junction temperature enable sustained reliability in thermally demanding automotive and industrial installations.
Can SMF4L28A-7 replace older SMAJ or SMBJ series TVS diodes?
Yes-SMF4L28A-7 matches SMAJ28A's electrical specs (28V VRWM, 45.4V VC, 400W) but in a 55% smaller DO-219AA package. Layout adaptation is required due to different pad geometry and polarity marking. No circuit redesign is needed for unidirectional DC rail protection applications.
Is SMF4L28A-7 compliant with automotive qualification standards?
Yes-SMF4L28A-7 is manufactured in IATF 16949-certified facilities and qualified to AEC-Q101 for discrete semiconductors. It meets stress test requirements including HTGB, HTRB, TCT, and surge endurance per JESD22-A114, making it suitable for under-hood and chassis-mounted automotive modules.
SMF4L28A-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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 8.8A
- 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
SMF4L28A-7 FAQ
1.How can I place an order for SMF4L28A-7 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF4L28A-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 SMF4L28A-7 reliable?
The price and inventory of SMF4L28A-7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF4L28A-7 is usually 5 days.
3.What payment methods are accepted for SMF4L28A-7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF4L28A-7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF4L28A-7?
SMF4L28A-7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF4L28A-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 SMF4L28A-7?
For technical support, including SMF4L28A-7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF4L28A-7 requirements.
6.How does Aetrix verify that SMF4L28A-7 is sourced from the original manufacturer or authorized distributors?
All SMF4L28A-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 SMF4L28A-7 meets industry standards.
7.What is the process for return or replacement of SMF4L28A-7?
All SMF4L28A-7 units undergo pre-shipment inspection (PSI). If there is an issue with SMF4L28A-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 SMF4L28A-7 part is unused and in its original packaging.
Return procedure for SMF4L28A-7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF4L28A-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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Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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