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onsemi SMF33AT1
- Part No.:
- SMF33AT1
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- SOD-123F
- Datasheet:
-
SMF33AT1.pdf
- Description:
- TVS DIODE 33VWM 53.3VC SOD123FL
- Quantity:
- Payment:
- Shipping:
Inventory:2,437
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Product details
Overview
SMF33AT1 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 33 V working peak reverse voltage (VRWM), 53.3 A maximum peak pulse current (IPP), 40.6 V maximum clamping voltage (VC) at IPP, and <1 ns response time. It is commonly deployed in 3.3 V–24 V industrial power supplies and USB interface protection circuits.
For engineers reviewing the SMF33AT1 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM margin above operating voltage, VC headroom relative to IC absolute maximum ratings, IEC61000-4-2/4-4 compliance level, and SOD-123FL footprint compatibility with high-density PCB layouts.
Technical Context
The SMF33AT1 operates as a Zener-based avalanche clamp, triggered when reverse voltage exceeds its breakdown threshold (VBR = 36.7–40.6 V). Its low zener impedance ensures stable clamping under fast transients such as ESD (16 kV HBM) and EFT (40 A per IEC61000-4-4).
Thermally, it uses a SOD-123FL package with RθJA = 325°C/W (on FR-4 with recommended pad), enabling 385 mW steady-state dissipation at 25°C ambient. Peak surge handling is rated at 200 W for 10/1000 µs waveform and 1000 W for 8/20 µs waveform - critical for automotive load-dump and industrial surge immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 33 V - must be ≥ circuit's max continuous DC voltage to avoid leakage-induced power loss |
| VBR (min/max) | 36.7 V / 40.6 V - defines reliable turn-on range; ensures clamping initiates before downstream IC damage thresholds |
| VC @ IPP | 40.6 V max at 53.3 A - determines worst-case voltage seen by protected IC during surge |
| IPP | 53.3 A - quantifies maximum transient energy the device can shunt without failure |
| Response Time | <1 ns - guarantees protection against sub-nanosecond ESD events before system logic latches fault |
| ESD Rating | Class 3 (>16 kV HBM), IEC61000-4-2 Level 4 - meets industrial and portable electronics immunity requirements |
| Package | SOD-123FL - 2.5 mm × 1.3 mm footprint, 1.0 mm max height; compatible with standard 8 mm tape-and-reel SMT assembly |
Pinout & Package
SOD-123FL is a surface-mount, flat-lead, two-terminal package with cathode indicated by a polarity band. Total footprint area is 8.45 mm²; maximum height is 1.0 mm. Mounting position is unrestricted; qualified for 260°C reflow (MSL 1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to protected line's higher-potential side (e.g., VBUS); reverse-biased during normal operation |
| 2 (Non-banded End) | Anode | Connected to ground or lower-potential reference; completes clamping path during overvoltage event |
Key Features
| Feature | Design Value |
|---|---|
| Low-profile SOD-123FL | 1.0 mm max height enables use in ultra-thin consumer devices and stacked PCB assemblies |
| IEC61000-4-2 Level 4 compliance | Withstands ±8 kV contact / ±15 kV air discharge - eliminates need for external ESD filters in USB/UART ports |
| Fast 10/1000 µs surge rating | 200 W peak power handling supports EN 61000-4-5 surge immunity up to 1 kV (2 Ω source) |
| Low leakage at VRWM | <1 µA at 33 V - prevents measurable standby current increase in battery-powered systems |
| Tape-and-reel packaging | 3,000 units per reel - optimized for high-throughput pick-and-place assembly without manual handling |
Applications
| USB 2.0 Data Line Protection | Industrial 24 V DC Power Rail |
|---|---|
Use Scenario: Protecting D+ and D− lines in embedded USB peripherals against ESD and cable-induced transients. IC Role / Device Role: Unidirectional TVS placed between each data line and ground, with VRWM selected below data eye voltage but above common-mode swing. Use Value: Prevents latch-up or permanent damage to USB transceivers while maintaining signal integrity due to low capacitance (<100 pF at 0 V). |
Use Scenario: Safeguarding PLC I/O modules and sensor interfaces powered from 24 V industrial supplies subject to switching surges and inductive kickback. IC Role / Device Role: Parallel-connected TVS across input terminals to clamp transients before they reach upstream regulators or microcontrollers. Use Value: Enables compliance with IEC 61000-4-4 (EFT) and IEC 61000-4-5 (surge) without adding bulkier MOVs or complex active clamps. |
| Automotive Body Control Module (BCM) | Point-of-Load (POL) Converter Input |
Use Scenario: Protecting LIN bus transceivers and low-voltage sensors in BCMs exposed to load-dump and jump-start conditions. IC Role / Device Role: Standoff-rated TVS placed at LIN physical layer input, sized to survive 12 V system transients up to 35 V for 400 ms. Use Value: Provides robustness against ISO 7637-2 Pulse 5a (load dump) with minimal board space versus larger DO-214 packages. |
Use Scenario: Shielding buck converter inputs from voltage spikes generated by hot-plug events or upstream switcher instability. IC Role / Device Role: Primary overvoltage clamp located immediately after input filter capacitor, before the controller IC's VIN pin. Use Value: Limits input voltage excursion to ≤40.6 V, preventing overvoltage shutdown or internal FET breakdown in 36 V-rated POL controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ33A | DO-214AC package; 33 V VRWM; 49.3 A IPP; 53.3 V VC - larger footprint (4.3 × 2.6 mm), higher thermal resistance | Better suited for higher-power 8/20 µs surges (>1 kW) where board space allows | Select SMAJ33A only if >1000 W surge capability is required and SOD-123FL height constraint does not apply |
| P6SMB33A | DO-214AA package; 33 V VRWM; 43.3 A IPP; 53.3 V VC - same VC but lower IPP; 1500 W peak rating | Higher surge rating but slower response (>1 ns typical); less effective for ESD | Prefer SMF33AT1 for ESD-critical interfaces; choose P6SMB33A only for cost-sensitive, non-ESD applications needing higher 8/20 µs energy handling |
Compared with SMAJ33A and P6SMB33A, the SMF33AT1 delivers superior ESD immunity and space efficiency in ultra-compact designs, while trading off absolute peak surge capacity - making it optimal for portable, USB, and space-constrained industrial control applications.
Availability
SMF33AT1 is available at Aetrix Electronics and suitable for industrial power supplies, USB peripheral protection, and automotive body electronics requiring stable component supply and full traceability.
Supply support for SMF33AT1 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, analog, sensing, 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 high-speed, low-capacitance overvoltage protection in space-constrained, high-reliability electronic systems.
FAQ
What is the working peak reverse voltage (VRWM) of the SMF33AT1?
The SMF33AT1 has a VRWM of 33 V, meaning it remains in high-impedance state up to this DC or continuous peak reverse voltage. This value is selected to exceed the nominal operating voltage of protected circuits - for example, it is appropriate for 24 V systems where transient margins require clamping above 30 V without leakage-induced power loss. The SMF33AT1 maintains <1 µA reverse leakage at 33 V.
How does the SMF33AT1 compare to bidirectional TVS diodes in ESD protection?
The SMF33AT1 is unidirectional and optimized for DC rail protection where polarity is fixed - it offers lower leakage and tighter VBR tolerance than bidirectional variants. Unlike bidirectional TVS diodes, the SMF33AT1 cannot protect AC signals or differential buses like RS-485 without additional circuitry. For USB data lines, the SMF33AT1 is used per-line (D+/D− to GND), whereas a bidirectional device would be needed for true differential clamping.
Can the SMF33AT1 be used in automotive applications compliant with ISO 7637-2?
Yes - the SMF33AT1 meets key requirements for ISO 7637-2 Pulse 1 (inductive load dump) and Pulse 2a (supply interruption) when applied with appropriate series impedance. Its 40.6 V clamping voltage at 53.3 A provides sufficient margin below the 42 V absolute maximum rating of many automotive MCUs. However, for full Pulse 5a (load dump) compliance, system-level testing with the actual vehicle network model is required, as SMF33AT1 alone does not absorb the full 12 V–35 V, 400 ms energy profile.
What is the thermal resistance and maximum power dissipation of the SMF33AT1?
The SMF33AT1 in SOD-123FL package has a junction-to-ambient thermal resistance (RθJA) of 325°C/W when mounted on FR-4 with the recommended minimum pad size. At 25°C ambient, this yields a maximum steady-state power dissipation of 385 mW. Derating is linear above 25°C - for example, at 85°C ambient, usable PD drops to ~220 mW. This makes the SMF33AT1 suitable for intermittent surge duty, not continuous power dissipation.
Is the SMF33AT1 RoHS-compliant and halogen-free?
Yes - the SMF33AT1 is manufactured by onsemi using lead-free (100% matte Sn) lead finish and void-free thermosetting plastic meeting UL94 VO. It complies with RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21, with bromine and chlorine content <900 ppm each. Full material declarations and PPAP documentation are available upon request for automotive and medical-grade programs.
SMF33AT1 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):
- 33V
- Voltage - Breakdown (Min):
- 36.7V
- Voltage - Clamping (Max) @ Ipp:
- 53.3V
- Current - Peak Pulse (10/1000µs):
- 3.8A
- 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
SMF33AT1 FAQ
1.How can I place an order for SMF33AT1 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF33AT1 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 SMF33AT1 reliable?
The price and inventory of SMF33AT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF33AT1 is usually 5 days.
3.What payment methods are accepted for SMF33AT1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF33AT1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF33AT1?
SMF33AT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF33AT1 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 SMF33AT1?
For technical support, including SMF33AT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF33AT1 requirements.
6.How does Aetrix verify that SMF33AT1 is sourced from the original manufacturer or authorized distributors?
All SMF33AT1 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 SMF33AT1 meets industry standards.
7.What is the process for return or replacement of SMF33AT1?
All SMF33AT1 units undergo pre-shipment inspection (PSI). If there is an issue with SMF33AT1, 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 SMF33AT1 part is unused and in its original packaging.
Return procedure for SMF33AT1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF33AT1 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
-
DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
-
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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