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onsemi SMF24AT1
- Part No.:
- SMF24AT1
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- SOD-123F
- Datasheet:
-
SMF24AT1.pdf
- Description:
- TVS DIODE 24VWM 38.9VC SOD123FL
- Quantity:
- Payment:
- Shipping:
Inventory:5,399
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Product details
Overview
SMF24AT1 from onsemi is a unidirectional transient voltage suppressor (TVS) diode designed for overvoltage protection of sensitive DC power rails and signal lines. It features a 24 V working peak reverse voltage (VRWM), 29.5 V maximum clamping voltage (VC) at 5.1 A peak pulse current, 200 W peak pulse power (10/1000 µs), <1 ns response time, and IEC61000-4-2 Level 4 ESD immunity (>16 kV HBM). It is used in portable electronics power input stages to absorb ESD and lightning-induced surges.
For engineers reviewing the SMF24AT1 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM matching system operating voltage, VC margin relative to IC absolute maximum ratings, surge current capability under IEC61000-4-4 40 A ring wave, thermal derating at elevated ambient temperatures, and SOD−123FL footprint compatibility with high-density PCB layouts.
Technical Context
The SMF24AT1 operates as a Zener-based avalanche clamp: under normal bias it presents <1 µA leakage at 24 V, but triggers into low-impedance conduction when transient voltage exceeds its 26.7–29.5 V breakdown range (VBR @ IT = 1 mA). Its fast <1 ns response ensures suppression before downstream ICs experience overstress.
Thermal performance is defined by RθJA = 325°C/W (on FR-4 with minimum pad), enabling 385 mW steady-state dissipation at 25°C ambient. Peak surge handling relies on junction-to-cathode thermal resistance (RθJcathode = 26°C/W) and short-duration energy absorption (1000 W @ 8/20 µs waveform).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 24 V - must be ≥ nominal DC rail voltage (e.g., 24 V industrial supply) to avoid leakage during normal operation |
| VBR min/max | 26.7 V / 29.5 V - defines guaranteed turn-on range; ensures clamping initiates before damage threshold of protected ICs |
| VC @ IPP | 38.9 V @ 5.1 A - maximum voltage seen by load during 10/1000 µs surge; determines required IC overvoltage margin |
| Peak Pulse Power | 200 W @ 10/1000 µs - supports common IEC61000-4-5 line surge test levels in compact SOD−123FL package |
| Response Time | <1 ns - enables protection of high-speed interfaces (e.g., RS-485, CAN FD transceivers) against ESD events |
| ESD Rating | >16 kV HBM, IEC61000-4-2 Level 4 - meets industrial equipment user-interface port immunity requirements |
| Leakage Current | <1 µA @ 24 V - negligible power loss in battery-powered devices; avoids false triggering in low-current sensor circuits |
Pinout & Package
SOD−123FL surface-mount plastic package (Case 498−01), 1.8 mm × 2.9 mm footprint, 1.0 mm max height, matte tin lead finish, MSL 1 rated, compatible with 260°C reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to protected line (e.g., +24 V rail); polarity band identifies cathode for correct orientation during placement |
| 2 (Non-banded End) | Anode | Connected to ground reference; forms low-impedance shunt path during overvoltage events |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SOD−123FL | 1.0 mm max height enables use in ultra-thin portable devices and stacked PCB assemblies |
| Small footprint area | 8.45 mm² saves board space vs. SMA/SMB packages-critical for handheld medical monitors and IoT sensors |
| High surge robustness | Withstands 40 A IEC61000-4-4 pulses without degradation-ensures long-term reliability in factory automation controllers |
| Tape-and-reel packaging | 3,000 units per 8 mm reel supports automated SMT assembly with standard pick-and-place feeders |
| UL94 VO epoxy | Flame-retardant housing meets IPC-CC-830B coating and safety standards for industrial power supplies |
Applications
| Industrial PLC I/O Module Protection | 24 V DC Power Input Stage |
|---|---|
Use Scenario: Protecting 24 V digital input channels in programmable logic controllers exposed to inductive switching transients from solenoids and relays. IC Role / Device Role / Timing Role: Unidirectional TVS placed between field-side input terminal and optocoupler input, clamping transients before they reach isolation barrier. Use Value: Limits voltage to ≤38.9 V during 1 A–5 A surges, preserving optocoupler CTR and preventing latch-up in upstream MCU GPIOs. |
Use Scenario: Safeguarding the main 24 V DC input of embedded gateways against hot-plug spikes and load-dump events. IC Role / Device Role / Timing Role: Primary front-end clamp mounted directly at connector entry point, shunting surge energy to chassis ground. Use Value: Absorbs up to 200 W peak power without failure, maintaining system uptime during brownout recovery cycles in smart building controllers. |
| RS-485 Transceiver Port | Medical Sensor Signal Line |
Use Scenario: Protecting differential A/B lines of isolated RS-485 transceivers in factory floor data loggers subjected to ESD from operator touch. IC Role / Device Role / Timing Role: One SMF24AT1 per line (A-to-GND, B-to-GND), providing bidirectional protection via dual-diode configuration. Use Value: Sub-1 ns response prevents data corruption during ±8 kV contact discharge, ensuring uninterrupted Modbus RTU communication. |
Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loop) of patient-worn vital sign sensors from electrostatic discharge during clinical handling. IC Role / Device Role / Timing Role: Low-leakage TVS placed at sensor PCB edge connector, guarding amplifier inputs without loading precision current sources. Use Value: <1 µA leakage at 24 V avoids offset errors in µA-level measurement circuits; 16 kV HBM rating exceeds IEC60601-1-2 clinical ESD requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ24A | Same VRWM (24 V) and VC (38.9 V), but SMA package (larger footprint, higher RθJA = 40°C/W) | Better thermal dissipation in high-ambient environments (>85°C), but requires 2.5× more board area | Select SMAJ24A only if board layout allows larger pad and thermal relief is prioritized over miniaturization |
| 1.5SMC24A | Higher peak power (1500 W), DO-214AB package, 3× larger size, 5× higher leakage (5 µA @ 24 V) | Suitable for AC mains-connected equipment requiring higher surge margin, not for space-constrained DC systems | Choose 1.5SMC24A for industrial motor drives with 6 kV IEC61000-4-5 compliance needs; avoid in battery-powered devices due to leakage |
Compared with SMF24AT1, SMAJ24A trades compactness for thermal headroom, while 1.5SMC24A sacrifices leakage performance and board area for extreme surge capacity-making SMF24AT1 optimal for miniaturized 24 V DC systems needing balanced ESD/surge protection.
Availability
SMF24AT1 is available at Aetrix Electronics and suitable for industrial automation controllers, medical sensor modules, and 24 V DC-powered IoT gateways requiring stable component supply across multi-year production cycles.
Supply support for SMF24AT1 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, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The SMF series belongs to onsemi's transient voltage suppressor portfolio, engineered specifically for space-constrained DC power rail and interface line protection in portable and ruggedized electronics.
FAQ
What is the maximum clamping voltage of the SMF24AT1 under surge conditions?
The SMF24AT1 has a maximum clamping voltage (VC) of 38.9 V when subjected to its rated peak pulse current of 5.1 A (10/1000 µs waveform). This value is guaranteed across temperature and represents the highest voltage the protected circuit will experience during a standardized surge event. Designers must ensure downstream components have absolute maximum voltage ratings exceeding 38.9 V to prevent damage. The SMF24AT1 achieves this clamping performance using a silicon avalanche structure optimized for low dynamic impedance.
Can the SMF24AT1 be used for bidirectional transient protection?
No, the SMF24AT1 is a unidirectional TVS diode and is not suitable for bidirectional protection without external circuitry. Its design clamps only positive transients on the cathode relative to anode (i.e., protects a positive rail against overvoltage to ground). For bidirectional applications like RS-485 or USB data lines, two SMF24AT1 devices must be connected in series opposing configuration, or a dedicated bidirectional part such as SMBJ24CA should be selected. Using a single SMF24AT1 on AC-coupled signals risks forward conduction and failure.
What is the recommended PCB footprint for the SMF24AT1 in SOD−123FL package?
The recommended PCB footprint for the SMF24AT1 follows onsemi's SOD−123FL specification: pad length 2.36 mm, pad width 1.22 mm, center-to-center spacing 3.40 mm, with solder mask defined pads to prevent bridging. This geometry ensures self-alignment during reflow and achieves the specified RθJA of 325°C/W on FR-4. Deviating from these dimensions-especially reducing pad area-degrades thermal performance and reduces surge endurance. The SMF24AT1 datasheet provides exact mechanical drawings (Case 498−01) for CAD library generation.
How does the SMF24AT1 perform under elevated ambient temperatures?
The SMF24AT1's surge capability derates linearly above 25°C ambient: at 85°C, its 200 W peak pulse power rating drops to approximately 120 W (60% of rated value), per Figure 4 in the datasheet. Steady-state power dissipation also decreases-its 385 mW DC rating falls to ~220 mW at 85°C. Designers must verify that worst-case surge energy (e.g., IEC61000-4-4 40 A) remains within the derated envelope. For high-temperature environments, thermal vias under the cathode pad or aluminum-core PCBs can mitigate junction temperature rise and preserve SMF24AT1 performance.
Is the SMF24AT1 compliant with RoHS and REACH regulations?
Yes, the SMF24AT1 is RoHS-compliant (lead-free, homogeneous material level) and REACH-conformant, with no SVHC substances above threshold concentrations. Its matte tin (Sn) lead finish meets J-STD-020 moisture sensitivity level 1 (MSL 1) requirements and supports Pb-free reflow profiles up to 260°C for 10 seconds. onsemi provides full material declarations and conflict minerals reporting through its product environmental compliance portal, confirming the SMF24AT1's suitability for global commercial and industrial deployments.
SMF24AT1 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):
- 24V
- Voltage - Breakdown (Min):
- 26.7V
- Voltage - Clamping (Max) @ Ipp:
- 38.9V
- Current - Peak Pulse (10/1000µs):
- 5.1A
- 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
SMF24AT1 FAQ
1.How can I place an order for SMF24AT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF24AT1 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 SMF24AT1 reliable?
The price and inventory of SMF24AT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF24AT1 is usually 5 days.
3.What payment methods are accepted for SMF24AT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF24AT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF24AT1?
SMF24AT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF24AT1 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 SMF24AT1?
For technical support, including SMF24AT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF24AT1 requirements.
6.How does Aetrix verify that SMF24AT1 is sourced from the original manufacturer or authorized distributors?
All SMF24AT1 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 SMF24AT1 meets industry standards.
7.What is the process for return or replacement of SMF24AT1?
All SMF24AT1 units undergo pre-shipment inspection (PSI). If there is an issue with SMF24AT1, 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 SMF24AT1 part is unused and in its original packaging.
Return procedure for SMF24AT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF24AT1 Tags
-
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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