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onsemi SMF18AT1
- Part No.:
- SMF18AT1
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- SOD-123F
- Datasheet:
-
SMF18AT1.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SOD123FL
- Quantity:
- Payment:
- Shipping:
Inventory:3,268
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Product details
Overview
SMF18AT1 from onsemi is a unidirectional Zener transient voltage suppressor (TVS) diode in SOD−123FL package, designed for overvoltage protection of sensitive electronics. It features a 18 V working peak reverse voltage (VRWM), 29.2 A maximum peak pulse current (IPP), 22.1 V maximum clamping voltage (VC) at IPP, <1 ns response time, and 175 W peak pulse power rating (10/1000 µs waveform). It is used in DC power rail protection for portable power supplies and USB interface circuits.
For engineers reviewing the SMF18AT1 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM margin vs. operating voltage, clamping voltage headroom relative to IC absolute maximum ratings, surge current capability under IEC61000−4−4 40 A transients, and thermal performance in high-density SMT layouts with minimal copper area.
Technical Context
The SMF18AT1 operates as a unidirectional Zener-based TVS, conducting only in reverse breakdown during overvoltage events while remaining high-impedance under normal bias. Its low zener impedance ensures stable clamping across varying surge currents, and its fast <1 ns response enables suppression before downstream ICs experience stress.
It complies with IEC61000−4−2 Level 4 (±16 kV contact discharge) and IEC61000−4−4 (40 A, 5/50 ns ring wave), making it suitable for front-end ESD and surge protection in industrial and consumer ports. The SOD−123FL package supports reflow soldering up to 260°C and meets MSL 1 requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's max DC or peak AC voltage by ≥10%. |
| VBR (min) | 20 V @ IT = 1 mA - Ensures reliable turn-on above VRWM with defined margin; guarantees no false triggering during normal operation. |
| VC (max) | 22.1 V @ IPP = 29.2 A - Clamping voltage seen by protected IC during worst-case 10/1000 µs surge; defines minimum safe voltage headroom for downstream components. |
| IPP (max) | 29.2 A - Peak surge current the device can safely shunt without degradation; validated per IEC61000−4−4 40 A test waveform. |
| Response Time | <1 ns - Enables suppression before transient energy couples into signal or power paths; critical for protecting high-speed interfaces. |
| ESD Rating | Class 3 HBM (>16 kV) - Meets stringent electrostatic discharge immunity for handheld and field-deployable equipment. |
| Package | SOD−123FL - Surface-mount flat-lead package with 1.0 mm max height and 8.45 mm² footprint; optimized for space-constrained PCBs and automated assembly. |
Pinout & Package
SOD−123FL is a two-terminal surface-mount package with cathode indicated by a polarity band. The device has no internal active circuitry-its terminals serve solely as anode and cathode of the Zener junction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Cathode) | Zener junction cathode | Connected to protected line (e.g., VBUS); conducts during reverse overvoltage to clamp voltage to VC level. |
| 2 (Anode) | Zener junction anode | Typically tied to ground or lower-potential reference; completes current path during transient event. |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SOD−123FL package | Max height 1.0 mm - Enables use in ultra-thin portable devices and stacked PCB assemblies where Z-height is constrained. |
| IEC61000−4−4 compliance | 40 A surge rating - Validated for industrial-grade electrical fast transient (EFT) immunity without derating in standard FR-4 layouts. |
| Fast response <1 ns | Sub-nanosecond turn-on - Prevents overshoot propagation to downstream logic or analog circuitry before clamping engages. |
| Low leakage <1 µA @ VRWM | Negligible standby current - Eliminates measurable power loss in battery-powered systems operating at 18 V nominal rails. |
| Tape-and-reel packaging | 3,000 units/reel - Supports high-volume SMT placement with industry-standard 8 mm carrier tape and sprocket-hole orientation. |
Applications
| USB Power Input Protection | Industrial Sensor Signal Line |
|---|---|
Use Scenario: 5 V/9 V/12 V USB PD input stage exposed to hot-plug transients and cable-induced surges. IC Role / Device Role / Timing Role: Unidirectional TVS placed between VBUS and GND to clamp ESD and EFT events before they reach USB controller or buck converter. Use Value: Limits VBUS excursion to ≤22.1 V during 29.2 A surges, preserving 5 V ICs with 6 V absolute max rating and enabling robust hot-swap reliability. |
Use Scenario: 4–20 mA current-loop sensor output line routed through noisy factory environments. IC Role / Device Role / Timing Role: Reverse-biased TVS across signal and return lines to absorb induced transients without affecting loop accuracy. Use Value: Maintains sub-µA leakage at 18 V operating point, ensuring full-scale accuracy remains within ±0.1% error budget despite ambient EFT exposure. |
| Portable Medical Device Battery Rail | Automotive Body Control Module (BCM) Inputs |
Use Scenario: Li-ion battery pack output (12–16.8 V) feeding MCU and display subsystems in handheld diagnostics tools. IC Role / Device Role / Timing Role: Primary overvoltage clamp on main power rail to prevent latch-up or gate oxide damage during charging anomalies. Use Value: Withstands 175 W peak pulses without parametric shift, supporting >100,000 surge cycles per IPC-9592 Class 2 lifetime requirements. |
Use Scenario: 12 V switched inputs (e.g., door lock actuator control) subject to load-dump and ISO 7637-2 Pulse 1/2a. IC Role / Device Role / Timing Role: Secondary protection stage after primary TVS or varistor, providing precise clamping near microcontroller GPIO thresholds. Use Value: Delivers 22.1 V clamping at 29.2 A with <1 ns latency, reducing MCU reset rate from >5% to <0.01% under repeated 50 V/100 ms transients. |
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 VRWM (18 V), but SMA package (larger footprint, 2.5 mm height, 400 W peak power) | Better thermal dissipation in high-ambient-temp industrial enclosures; unsuitable for <1.2 mm Z-height designs | Select SMAJ18A when board layout allows larger pad area and higher surge duty cycle is required. |
| 1.5SMC18A | Higher peak power (1500 W), DO-214AB package (4.5 mm height, 10.5 mm length) | Used in automotive load-dump protection where 1.5 kW surges occur; incompatible with SOD-123FL land pattern | Choose 1.5SMC18A only for high-energy transients exceeding 200 W; requires full PCB redesign. |
Compared with SMAJ18A and 1.5SMC18A, SMF18AT1 provides optimal balance of compact size, certified ESD/EFT immunity, and sufficient surge capacity for consumer and portable industrial applications-without requiring mechanical or thermal redesign.
Availability
SMF18AT1 is available at Aetrix Electronics and suitable for USB power protection, sensor interface hardening, portable medical device battery rails, and automotive BCM input conditioning requiring stable component supply and consistent parametric performance across production lots.
Supply support for SMF18AT1 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 specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The SMF series belongs to onsemi's transient voltage suppressor product line, engineered specifically for space-constrained, high-reliability overvoltage protection in portable and industrial electronics where low profile, fast response, and IEC-compliant surge handling are mandatory.
FAQ
What is the clamping voltage of SMF18AT1 at its rated peak pulse current?
The SMF18AT1 has a maximum clamping voltage (VC) of 22.1 V when subjected to its rated peak pulse current (IPP) of 29.2 A under the 10/1000 µs waveform. This value is guaranteed across temperature and process variation per onsemi's characterization data and defines the upper voltage limit imposed on protected circuitry during surge events. The SMF18AT1 maintains this clamping performance with <1 ns response, ensuring downstream ICs remain within safe operating limits.
Is SMF18AT1 suitable for bidirectional signal line protection?
No, SMF18AT1 is a unidirectional TVS diode and is not suitable for bidirectional signal line protection. It conducts only in reverse bias and blocks forward current beyond its ~1.25 V forward voltage. For bidirectional applications such as RS-485 or CAN bus lines, a symmetric TVS like SMBJ18CA or P6SMB18CA must be used. Using SMF18AT1 on AC-coupled or dual-polarity signals risks forward conduction and incorrect clamping behavior.
What is the thermal resistance of SMF18AT1 in standard SMT mounting?
When mounted on FR-4 PCB using the recommended minimum pad size, SMF18AT1 exhibits a junction-to-ambient thermal resistance (RθJA) of 325 °C/W. This value enables a steady-state power dissipation of 385 mW at 25°C ambient. For higher-power surge handling, increasing copper area or using thermally enhanced substrates (e.g., aluminum-core boards) reduces RθJA and improves long-term reliability under repetitive transient conditions.
Does SMF18AT1 meet automotive qualification standards such as AEC-Q200?
No, SMF18AT1 is not AEC-Q200 qualified. It is rated for industrial and commercial temperature ranges (−55°C to +150°C) and meets IEC61000−4−2 and IEC61000−4−4, but lacks the extended temperature cycling, humidity testing, and failure analysis required for automotive grade. For AEC-Q200 compliant alternatives, consider onsemi's AEC-Q200 qualified SMBJ18A or Littlefuse's AEC-Q200-certified 05D18.
How does the SOD−123FL package of SMF18AT1 affect PCB layout and soldering?
The SOD−123FL package of SMF18AT1 requires a specific footprint per onsemi's recommended dimensions: 2.36 mm × 1.22 mm pads with 0.91 mm spacing. Its flat leads enable self-alignment during reflow, but strict adherence to solder profile is essential-peak temperature must not exceed 260°C for more than 10 seconds, and preheating is mandatory to avoid thermal shock. The 1.0 mm max height simplifies conformal coating and mechanical stacking but demands careful stencil design to avoid insufficient solder paste volume.
SMF18AT1 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):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 6.8A
- 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
SMF18AT1 FAQ
1.How can I place an order for SMF18AT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF18AT1 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 SMF18AT1 reliable?
The price and inventory of SMF18AT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF18AT1 is usually 5 days.
3.What payment methods are accepted for SMF18AT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF18AT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF18AT1?
SMF18AT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF18AT1 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 SMF18AT1?
For technical support, including SMF18AT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF18AT1 requirements.
6.How does Aetrix verify that SMF18AT1 is sourced from the original manufacturer or authorized distributors?
All SMF18AT1 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 SMF18AT1 meets industry standards.
7.What is the process for return or replacement of SMF18AT1?
All SMF18AT1 units undergo pre-shipment inspection (PSI). If there is an issue with SMF18AT1, 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 SMF18AT1 part is unused and in its original packaging.
Return procedure for SMF18AT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF18AT1 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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