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onsemi SMF45AT1G
- Part No.:
- SMF45AT1G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- SOD-123F
- Datasheet:
-
SMF45AT1G.pdf
- Description:
- TVS DIODE 45VWM 72.7VC SOD123FL
- Quantity:
- Payment:
- Shipping:
Inventory:2,405
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Product details
Overview
SMF45AT1G from onsemi is a unidirectional Zener transient voltage suppressor (TVS) diode in SOD-123FL package, designed for clamping ESD and surge transients on DC power rails and signal lines. It features a 45 V working peak reverse voltage (VRWM), 52.65 V minimum breakdown voltage (VBR), 55.3 V maximum clamping voltage (VC) at 72.7 A peak pulse current (IPP), and <1 ns response time - ideal for protecting USB ports, industrial I/O interfaces, and 48 V telecom power inputs.
For engineers reviewing the SMF45AT1G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, real-world protection use cases, validated alternatives, and supply-chain-ready availability details - all grounded in onsemi's official SMF5.0AT1 Series documentation (Rev. 2, May 2007).
Technical Context
The SMF45AT1G operates as a unidirectional avalanche diode, entering low-impedance conduction when reverse voltage exceeds its VBR of 50–55.3 V. Its clamping action limits transient energy to ≤72.7 A (10/1000 µs waveform) while maintaining VC ≤55.3 V - ensuring downstream ICs see no more than safe overvoltage stress.
It meets IEC61000-4-2 Level 4 (±16 kV contact discharge) and IEC61000-4-4 (40 A surge), with <1 nA leakage at VRWM and thermal resistance RJA = 325 °C/W on FR-4 board. The Pb-free matte tin lead finish supports 260 °C reflow and MSL 1 handling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 45 V - Maximum continuous reverse operating voltage before clamping begins; matches 48 V nominal systems with 10% tolerance margin. |
| VBR (min) | 50 V - Guaranteed avalanche onset at test current IT = 1 mA; ensures reliable triggering above system operating voltage. |
| VC (max) | 55.3 V @ IPP = 72.7 A - Peak clamped voltage during worst-case 10/1000 µs surge; defines absolute overvoltage limit seen by protected circuitry. |
| IPP | 72.7 A - Maximum non-repetitive peak pulse current it can safely shunt without degradation. |
| Response time | <1 ns - Enables suppression of fast-rising ESD events before sensitive logic or analog circuits are damaged. |
| ESD rating | Class 3 HBM (>16 kV) - Complies with JEDEC JS-001-2017 for robust human-body-model electrostatic discharge immunity. |
| Package | SOD-123FL - Surface-mount, low-profile (1.0 mm max height), 8.45 mm² footprint; optimized for space-constrained PCB layouts. |
Pinout & Package
SOD-123FL is a two-terminal surface-mount plastic package with cathode indicated by a polarity band. Mounting position is unrestricted; qualified for 260 °C reflow and MSL 1 handling.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded end) | Cathode | Connected to protected line (e.g., VBUS, RS-485 A); conducts during reverse transient to clamp voltage. |
| 2 (Non-banded end) | Anode | Connected to ground or lower-potential reference; completes current path during surge event. |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SOD-123FL package | 1.0 mm max height enables placement under connectors or near edge-mounted I/O, minimizing trace inductance in high-speed protection paths. |
| IEC61000-4-2 Level 4 compliance | Withstands ±16 kV contact discharge - eliminates need for external ESD staging components in USB 2.0/3.0, HDMI, and industrial sensor interfaces. |
| 72.7 A peak pulse capability | Handles 40 A IEC61000-4-4 surges with margin, supporting robust front-end protection in 48 V PoE-powered equipment and PLC analog input modules. |
| 100% matte tin lead finish | Enables lead-free assembly without solderability degradation or whisker risk; qualified per J-STD-020D.1 for MSL 1. |
Applications
| USB 2.0 Data Lines | 48 V Telecom Power Input |
|---|---|
Use Scenario: Protecting D+ and D− lines in USB host/device ports against ESD events during hot-plug insertion. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between each data line and ground, clamping transients before they reach USB transceiver ICs. Use Value: Limits voltage excursion to ≤55.3 V during ±16 kV ESD strikes, preserving signal integrity and preventing latch-up in PHY layers. | Use Scenario: Safeguarding DC-DC converter inputs in telecom base station power supplies exposed to lightning-induced surges. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 48 V rail, absorbing up to 72.7 A (10/1000 µs) before upstream fusing activates. Use Value: Maintains system uptime by preventing catastrophic failure of buck controllers and gate drivers during outdoor-installed equipment surges. |
| Industrial RS-485 Transceivers | Programmable Logic Controller (PLC) Analog Inputs |
Use Scenario: Protecting half-duplex RS-485 bus nodes in factory automation networks subject to cable-coupled transients. IC Role / Device Role / Timing Role: Bidirectional protection implemented using two SMF45AT1G devices (anode-to-anode configuration) across A/B lines and ground. Use Value: Clamps common-mode surges to ≤55.3 V while preserving differential signaling integrity - enabling >1000 m cable runs in electrically noisy environments. | Use Scenario: Shielding 0–10 V or 4–20 mA analog input channels in modular PLC backplanes from field-wiring induced transients. IC Role / Device Role / Timing Role: Front-end transient suppressor mounted directly at terminal block entry point, before precision op-amp conditioning stages. Use Value: Prevents offset drift and saturation in instrumentation amplifiers by limiting input overvoltage to safe levels during maintenance or wiring faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ45A | Same VRWM (45 V) and VC (58.1 V), but in larger SMA package (RJA = 50°C/W vs. 325°C/W); 400 W peak power vs. 200 W. | Better thermal dissipation for repetitive surges; less suitable for ultra-thin handheld PCBs due to 2.3 mm height. | Select SMAJ45A when surge duty cycle exceeds 1 pulse/minute or board copper area allows larger footprint. |
| P6SMB45A | Higher VRWM tolerance (45 V vs. 45 V), identical VC (58.1 V), but DO-214AA package; 600 W peak power, RJA = 30°C/W. | Designed for high-energy AC line protection; not optimized for low-capacitance signal-line use. | Choose P6SMB45A only for primary-side AC/DC input protection where size is secondary to energy handling. |
Compared with SMAJ45A and P6SMB45A, the SMF45AT1G offers superior board-space efficiency and faster response in compact DC systems, trading off absolute energy capacity for minimal parasitic inductance and compatibility with fine-pitch routing - making it optimal for USB, RS-485, and 48 V embedded power rails.
Availability
SMF45AT1G is available at Aetrix Electronics and suitable for USB interface protection, 48 V telecom power inputs, industrial RS-485 networks, and PLC analog input conditioning requiring stable component supply across production lifecycles.
Supply support for SMF45AT1G 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 (Nasdaq: ON) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The SMF5.0AT1 Series - including SMF45AT1G - was engineered specifically for high-reliability, low-profile transient suppression in space-constrained DC systems, targeting ESD and surge resilience in portable electronics and industrial control hardware.
FAQ
What is the clamping voltage of SMF45AT1G at its rated peak pulse current?
The SMF45AT1G has a maximum clamping voltage (VC) of 55.3 V when subjected to its rated peak pulse current (IPP) of 72.7 A under the 10/1000 µs waveform. This value is guaranteed across temperature and manufacturing lot, ensuring consistent overvoltage protection for downstream circuitry in designs using SMF45AT1G.
Is SMF45AT1G unidirectional or bidirectional, and how does that affect its circuit placement?
The SMF45AT1G is a unidirectional TVS diode, meaning it conducts only during reverse-biased transients - i.e., when cathode voltage exceeds anode voltage. In practice, this requires connecting its cathode to the protected line (e.g., VBUS or RS-485 A) and anode to ground. For bidirectional protection, two SMF45AT1G devices must be used in anode-to-anode configuration.
Does SMF45AT1G meet IEC61000-4-2 and IEC61000-4-4 standards, and what levels?
Yes, SMF45AT1G is rated for IEC61000-4-2 Level 4 (±16 kV contact discharge) and IEC61000-4-4 (40 A surge current, 5/50 ns waveform). These certifications are explicitly stated in the onsemi SMF5.0AT1 Series datasheet (Rev. 2), confirming its suitability for ESD-hardened USB, industrial I/O, and telecom interfaces where SMF45AT1G serves as the first line of defense.
What is the thermal resistance (RJA) of SMF45AT1G, and how does it impact layout design?
The SMF45AT1G has a junction-to-ambient thermal resistance (RJA) of 325 °C/W when mounted on FR-4 board with recommended minimum pad size. This relatively high value means it relies on short-duration transient absorption rather than sustained power dissipation - so PCB layout should minimize trace length to ground and avoid thermal isolation; large copper pours are unnecessary and may increase parasitic capacitance in signal-line applications using SMF45AT1G.
Can SMF45AT1G replace SMAJ45A in an existing design without board changes?
No - SMF45AT1G uses the SOD-123FL package (2.7 × 1.6 mm), while SMAJ45A uses SMA (4.5 × 2.7 mm). Their footprints and thermal pads are incompatible. Although both have 45 V VRWM and similar clamping behavior, direct substitution would require PCB redesign. Engineers evaluating SMF45AT1G versus SMAJ45A must account for mechanical fit, thermal path, and layout density - SMF45AT1G is not a drop-in replacement for SMAJ45A.
SMF45AT1G 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):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.7V
- Current - Peak Pulse (10/1000µs):
- 2.8A
- 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
SMF45AT1G FAQ
1.How can I place an order for SMF45AT1G through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF45AT1G 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 SMF45AT1G reliable?
The price and inventory of SMF45AT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF45AT1G is usually 5 days.
3.What payment methods are accepted for SMF45AT1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF45AT1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF45AT1G?
SMF45AT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF45AT1G 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 SMF45AT1G?
For technical support, including SMF45AT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF45AT1G requirements.
6.How does Aetrix verify that SMF45AT1G is sourced from the original manufacturer or authorized distributors?
All SMF45AT1G 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 SMF45AT1G meets industry standards.
7.What is the process for return or replacement of SMF45AT1G?
All SMF45AT1G units undergo pre-shipment inspection (PSI). If there is an issue with SMF45AT1G, 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 SMF45AT1G part is unused and in its original packaging.
Return procedure for SMF45AT1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF45AT1G 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
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D12V0L1B2LP-7B
Diodes Incorporated
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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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