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onsemi SMF78AT1G
- Part No.:
- SMF78AT1G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- SOD-123F
- Datasheet:
-
SMF78AT1G.pdf
- Description:
- TVS DIODE 78VWM 126VC SOD123FL
- Quantity:
- Payment:
- Shipping:
Inventory:2,112
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Product details
Overview
SMF78AT1G from onsemi is a unidirectional Zener transient voltage suppressor (TVS) diode in SOD-123FL package, designed to protect sensitive electronics against ESD and surge transients. It features a 78 V working peak reverse voltage (VRWM), 95.8 V maximum clamping voltage (VC) at 126 A peak pulse current, and <1 ns response time - ideal for DC power rail protection in industrial power supplies and telecom infrastructure.
For engineers reviewing the SMF78AT1G datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM margin over operating voltage, clamping voltage headroom relative to IC absolute maximum ratings, IEC 61000-4-2/4-4 compliance, and thermal performance under repetitive surge conditions.
Technical Context
The SMF78AT1G operates as a unidirectional Zener-based TVS, conducting only during reverse overvoltage events above its breakdown threshold (VBR = 86.7–95.8 V). Its low zener impedance ensures stable clamping under high-current transients up to 126 A (10/1000 µs waveform).
It delivers 200 W peak pulse power (1 ms) and meets IEC61000-4-2 Level 4 (±16 kV contact, ±15 kV air) and IEC61000-4-4 (40 A, 5/50 ns) immunity standards. The device is Pb-free, qualified to MSL 1, and rated for -55°C to +150°C operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 78 V - minimum reverse standoff voltage before conduction; must exceed system's max continuous DC rail voltage. |
| VBR (min/typ/max) | 86.7 / 91.25 / 95.8 V - breakdown occurs within this range at 1 mA test current; defines turn-on threshold. |
| VC @ IPP | 95.8 V @ 126 A - maximum clamped voltage during 10/1000 µs surge; determines protected IC's voltage stress. |
| IPP | 126 A - peak pulse current capability; sets surge energy handling (175 W for >60 V variants). |
| IR @ VRWM | 1 µA - leakage current at 78 V; negligible loading on 78 V supply rails. |
| Response Time | <1 ns - enables suppression of fast ESD edges before downstream ICs are damaged. |
| ESD Rating | Class 3 HBM (>16 kV) - qualifies for direct interface protection in handheld and industrial I/O ports. |
Pinout & Package
SOD-123FL surface-mount package: 1.0 mm max height, 2.7 mm × 1.6 mm footprint (8.45 mm²), cathode-indicated by band. RoHS-compliant matte tin lead finish, MSL 1, reflow-compatible to 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to protected circuit's positive rail; conducts when transient exceeds VRWM. |
| 2 (Non-banded End) | Anode | Connected to ground or lower-potential reference; completes clamping path during overvoltage. |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SOD-123FL | 1.0 mm max height enables use in space-constrained PCB layouts like telecom modules and DIN-rail controllers. |
| IEC61000-4-4 Compliance | 40 A surge immunity (5/50 ns) supports robust front-end protection in industrial Ethernet and PLC analog inputs. |
| Fast <1 ns Response | Prevents sub-microsecond ESD pulses from propagating to microcontrollers or ADCs on shared power domains. |
| Pb-Free & MSL 1 | Enables lead-free reflow assembly without moisture sensitivity concerns or baking requirements. |
Applications
| Industrial Power Supply Protection | Telecom DC Input Protection |
|---|---|
Use Scenario: 48 V DC input stage of programmable logic controller (PLC) power module exposed to load dump and lightning-induced surges. IC Role / Device Role / Timing Role: Unidirectional TVS clamps transients on +48 V rail to prevent damage to upstream DC-DC controllers and downstream 5 V/3.3 V regulators. Use Value: 95.8 V clamping voltage provides 17.8 V margin below typical 113.6 V load-dump peak, ensuring safe operation per ISO 7637-2. | Use Scenario: Primary DC input (−48 V or +24 V) of base station radio unit subject to IEC 61000-4-5 line surge. IC Role / Device Role / Timing Role: Standoff protection element placed directly at connector entry point to shunt surge energy to chassis ground before reaching PMICs and FPGAs. Use Value: 126 A peak pulse rating handles 10/1000 µs surges up to 175 W, meeting GR-1089-CORE Class B requirements. |
| Industrial Sensor Interface Protection | Factory Automation I/O Module |
Use Scenario: 24 V two-wire loop-powered pressure transmitter connected to control cabinet via unshielded cable runs. IC Role / Device Role / Timing Role: Reverse-polarity and surge protection diode on 24 V supply line, placed before internal LDO and signal conditioning circuitry. Use Value: 1 µA leakage at 78 V ensures minimal impact on 4–20 mA loop accuracy; low capacitance preserves signal integrity. | Use Scenario: Digital input card receiving 24 V dry-contact signals in harsh factory environments with frequent ESD events. IC Role / Device Role / Timing Role: Point-of-entry TVS on each channel's 24 V supply rail to clamp contact bounce transients and operator ESD. Use Value: Class 3 HBM (>16 kV) rating eliminates need for external spark gaps; SOD-123FL allows dense 16-channel layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A | Higher clamping voltage (121 V @ 100 A); SMA package (larger footprint, higher thermal mass). | Less suitable for tight VRWM margin designs; better for higher-energy 8/20 µs surges due to 400 W rating. | Select SMAJ78A only if board space permits larger package and clamping voltage margin allows. |
| P6SMB78A | Same VRWM (78 V) but higher VC (121 V @ 100 A); SMB package (3.6 mm × 2.8 mm), 600 W peak power. | Used where higher surge repetition rate or longer pulse duration (8/20 µs) dominates over compactness. | Choose P6SMB78A when system-level testing shows SMA/SOD-123FL clamping insufficient for worst-case surge profiles. |
Compared with SMAJ78A and P6SMB78A, the SMF78AT1G offers the smallest footprint and lowest clamping voltage among 78 V unidirectional TVS diodes, making it optimal for space-constrained, low-voltage-margin applications - though its 175 W rating requires careful thermal design under repetitive surge conditions.
Availability
SMF78AT1G is available at Aetrix Electronics and suitable for industrial power supply protection, telecom DC input protection, and factory automation I/O modules requiring stable component supply across long production lifecycles.
Supply support for SMF78AT1G 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.
The SMF series belongs to onsemi's transient voltage suppressor product line, engineered specifically for compact, high-reliability overvoltage protection in DC power systems and interface circuits.
FAQ
What is the working peak reverse voltage (VRWM) of the SMF78AT1G?
The SMF78AT1G has a VRWM of 78 V, meaning it remains non-conductive up to this DC or continuous peak reverse voltage. This value ensures compatibility with 72–75 V nominal systems while providing margin against ripple and tolerance drift. The SMF78AT1G begins clamping above its specified breakdown voltage range of 86.7–95.8 V.
Does the SMF78AT1G meet IEC 61000-4-2 and IEC 61000-4-4 standards?
Yes, the SMF78AT1G is rated for Class 3 HBM ESD (>16 kV) per IEC 61000-4-2 Level 4 and provides 40 A surge immunity per IEC 61000-4-4 (5/50 ns). These certifications are verified in onsemi's official datasheet Rev. 2 and apply directly to the SMF78AT1G in SOD-123FL packaging.
What is the maximum clamping voltage (VC) of the SMF78AT1G and at what current?
The SMF78AT1G has a maximum clamping voltage (VC) of 95.8 V at 126 A peak pulse current (10/1000 µs waveform). This value defines the highest voltage seen by downstream components during a worst-case transient, and is critical for ensuring protected ICs remain within their absolute maximum ratings.
Is the SMF78AT1G unidirectional or bidirectional, and how is polarity marked?
The SMF78AT1G is a unidirectional TVS diode, intended for DC rail protection where reverse polarity is not expected. Polarity is marked by a cathode band on the SOD-123FL package - terminal 1 (banded end) is cathode and connects to the positive rail; terminal 2 (non-banded end) is anode and connects to ground.
What package type and mounting specifications does the SMF78AT1G use?
The SMF78AT1G uses the SOD-123FL (Case 498) surface-mount package: 2.7 mm × 1.6 mm footprint, 1.0 mm max height, matte tin leads, MSL 1 rating, and 260°C reflow compatibility. Its low profile and small area make it suitable for high-density industrial PCBs where thermal relief and mechanical robustness are balanced.
SMF78AT1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- SOD-123F
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 1.4A
- Power - Peak Pulse:
- 200W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123FL
SMF78AT1G FAQ
1.How can I place an order for SMF78AT1G through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF78AT1G 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 SMF78AT1G reliable?
The price and inventory of SMF78AT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF78AT1G is usually 5 days.
3.What payment methods are accepted for SMF78AT1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF78AT1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF78AT1G?
SMF78AT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF78AT1G 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 SMF78AT1G?
For technical support, including SMF78AT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF78AT1G requirements.
6.How does Aetrix verify that SMF78AT1G is sourced from the original manufacturer or authorized distributors?
All SMF78AT1G 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 SMF78AT1G meets industry standards.
7.What is the process for return or replacement of SMF78AT1G?
All SMF78AT1G units undergo pre-shipment inspection (PSI). If there is an issue with SMF78AT1G, 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 SMF78AT1G part is unused and in its original packaging.
Return procedure for SMF78AT1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF78AT1G Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
Diodes Incorporated
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ESD5Z3.3T1G
onsemi
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D5V0H1B2LP-7B
Diodes Incorporated
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D5V0P1B2LP-7B
Diodes Incorporated
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DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
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DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
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D5V0L1B2WS-7
Diodes Incorporated
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