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Taiwan Semiconductor Corporation SMF20A
- Part No.:
- SMF20A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF20A.pdf
- Description:
- TVS DIODE 20VWM 32.4VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:6,134
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Product details
Overview
SMF20A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy ESD and surge protection in DC power rails and signal lines. It features a 20 V working stand-off voltage (VWM), 22.2–24.5 V breakdown voltage (VBR), 32.4 V clamping voltage (VC) at 6.2 A peak pulse current, and 200 W peak pulse power (10/1000 µs waveform), making it suitable for automotive load-dump and industrial I/O port protection.
For engineers reviewing the SMF20A datasheet, SMF20A pinout, SMF20A application, or SMF20A equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b, low leakage (<1 µA @ 20 V), SOD-123W package compatibility with automated placement, and thermal resistance (RθJL = 33 °C/W) for PCB-level thermal management.
Technical Context
The SMF20A operates as a unidirectional avalanche diode, activated when reverse voltage exceeds its breakdown threshold (22.2–24.5 V). Its glass-passivated junction ensures stable VBR tolerance and low leakage, while its 10/1000 µs waveform rating supports robust immunity against inductive switching transients and EFT bursts.
Designed for surface-mount integration on 5 mm × 5 mm copper pads, the device delivers 200 W peak pulse power with clamping limited to 32.4 V at 6.2 A - enabling reliable protection of 24 V systems without overstressing downstream ICs such as CAN transceivers, microcontrollers, or sensor interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 22.2 V / 24.5 V - guaranteed avalanche initiation range at 1 mA test current |
| VC @ IPPM | 32.4 V - clamped voltage during 6.2 A 10/1000 µs surge, limiting stress on protected circuitry |
| PPPM | 200 W - peak pulse power handling per ISO 7637-2-compliant transient waveforms |
| IR @ VWM | <1 µA - negligible leakage at rated stand-off voltage, preserving low-power system integrity |
| RθJL | 33 °C/W - junction-to-lead thermal resistance enables efficient heat transfer to PCB copper |
| Package | SOD-123W - compact, RoHS-compliant, halogen-free surface-mount package with matte tin leads |
Pinout & Package
SOD-123W is a two-terminal surface-mount package with cathode indicated by a band; terminals are anode (unmarked end) and cathode (banded end). The device is mounted with the cathode connected to the line requiring protection and anode to ground or lower potential rail.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Reference node (typically GND) | Provides return path for clamped surge current; must connect to low-impedance ground plane |
| Cathode | Protected line input | Connected to the signal or power line being safeguarded; clamps to anode when overvoltage occurs |
Key Features
| Feature | Design Value |
|---|---|
| Photo glass-passivated junction | Ensures tight VBR tolerance (±5%), stable long-term leakage performance, and resistance to environmental degradation |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (EFT), meeting automotive EMC requirements |
| Moisture sensitivity level 1 | Enables standard SMT reflow without baking; compatible with J-STD-020 moisture handling protocols |
| UL 94V-0 molding compound | Provides flame-retardant encapsulation essential for industrial and transportation safety certifications |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 24 V supply lines in body control modules from load-dump transients up to ±100 V. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between battery rail and local regulator input. Use Value: Clamps surges to ≤32.4 V within nanoseconds, preventing damage to LDOs and microcontrollers rated for 36 V absolute max. | Use Scenario: Safeguarding analog inputs of 4–20 mA current-loop sensors exposed to field wiring ESD events. IC Role / Device Role / Timing Role: Reverse-biased TVS across sensor input terminals to shunt fast transients before they reach precision op-amps. Use Value: Sub-1 µA leakage at 20 V avoids loading sensitive current-sense nodes; 32.4 V clamping preserves 24 V system headroom. |
| Consumer USB Port ESD Protection | Smart Meter Communication Line Protection |
Use Scenario: Adding secondary ESD protection on VBUS line of USB 2.0 ports in set-top boxes and gateways. IC Role / Device Role / Timing Role: Standoff-rated TVS placed upstream of USB power switch to absorb contact discharge up to ±15 kV (IEC 61000-4-2). Use Value: 20 V VWM allows operation across full USB 2.0 VBUS range (4.75–5.25 V nominal + margin); low capacitance minimizes signal distortion. | Use Scenario: Protecting RS-485 transceiver pins in utility smart meters installed in electrically noisy substations. IC Role / Device Role / Timing Role: Unidirectional TVS on DE/RE control lines and differential bus pairs to suppress lightning-induced surges. Use Value: 200 W peak power rating handles repetitive 10/1000 µs surges per IEC 61000-4-5 Level 3; SOD-123W footprint fits dense meter PCB layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ20A (Bourns) | Same VWM (20 V), higher PPPM (600 W), larger SMB package (4.5 × 3.9 mm vs. SOD-123W's 2.7 × 1.6 mm) | Better suited for higher-energy surges but requires more board area and different pad layout | Select SMBJ20A only if 600 W surge rating is required and PCB space permits larger footprint |
| P6SMB20A (ON Semiconductor) | Identical VWM (20 V), same SOD-123W package, slightly higher VC (34.0 V vs. 32.4 V) and lower IPPM (5.8 A) | Nearly drop-in replacement; minor clamping voltage trade-off for cost-sensitive industrial designs | Acceptable alternative where 1.6 V higher clamping is tolerable and second-source qualification is needed |
Compared with SMBJ20A and P6SMB20A, the SMF20A offers the optimal balance of compact SOD-123W size, 32.4 V clamping, and ISO 7637-2 compliance - making it preferred for space-constrained automotive and industrial modules where precise voltage limiting is critical.
Availability
SMF20A is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, consumer USB power protection, and smart meter communication lines requiring stable component supply and consistent surge performance across production batches.
Supply support for SMF20A 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for industrial, automotive, and consumer markets.
The SMF series was developed specifically for high-reliability, surface-mount transient suppression in harsh environments - emphasizing low leakage, tight VBR tolerance, and compliance with ISO 7637-2 and IEC 61000-4-x standards.
FAQ
What is the maximum clamping voltage of SMF20A under a 10/1000 µs surge?
The SMF20A has a maximum clamping voltage (VC) of 32.4 V when subjected to a 6.2 A peak pulse current with a 10/1000 µs waveform. This value is measured per standard test conditions (TA = 25°C) and ensures downstream components see limited overvoltage stress during transient events. The SMF20A maintains this clamping performance across its specified junction temperature range of –55°C to +175°C.
Is SMF20A unidirectional or bidirectional, and how does that affect circuit placement?
The SMF20A is a unidirectional TVS diode, meaning it conducts only in reverse bias above its breakdown voltage. It must be placed with the cathode toward the protected line and anode to ground or reference potential. This configuration provides superior low-leakage performance (<1 µA @ 20 V) compared to bidirectional variants, making SMF20A ideal for DC power rail protection where polarity is fixed.
Does SMF20A meet automotive transient immunity standards?
Yes, the SMF20A meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a/2b (supply interruption and coupling), and Pulse 3a/3b (electrical fast transients). Its 200 W peak pulse power rating and verified clamping behavior under these waveforms make SMF20A suitable for front-end protection in automotive ECUs, body controllers, and infotainment power supplies.
What is the thermal resistance of SMF20A, and why does it matter for PCB layout?
The SMF20A has a junction-to-lead thermal resistance (RθJL) of 33 °C/W when mounted on a 5 mm × 5 mm copper pad. This parameter directly impacts how effectively heat from surge events dissipates into the PCB. To maintain reliability, designers should use adequate copper pour around the SOD-123W pads and avoid narrow traces - ensuring the SMF20A remains within its 175°C maximum junction temperature during repeated transient events.
Can SMF20A be used in place of SMAJ20A in an existing design?
No - SMF20A and SMAJ20A are not direct replacements due to differing packages (SOD-123W vs. SMA) and thermal characteristics. While both have 20 V VWM, SMAJ20A uses a larger SMA package with higher thermal mass and different RθJA. Replacing SMAJ20A with SMF20A requires verifying PCB pad layout, surge repetition rate limits, and clamping margin - especially since SMF20A's lower RθJL improves heat transfer but reduces total energy absorption per event.
SMF20A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- SOD-123W
- Series:
- SMF
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 6.2A
- Power - Peak Pulse:
- 200W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123W
SMF20A FAQ
1.How can I place an order for SMF20A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF20A 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 SMF20A reliable?
The price and inventory of SMF20A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF20A is usually 5 days.
3.What payment methods are accepted for SMF20A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF20A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF20A?
SMF20A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF20A 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 SMF20A?
For technical support, including SMF20A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF20A requirements.
6.How does Aetrix verify that SMF20A is sourced from the original manufacturer or authorized distributors?
All SMF20A 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 SMF20A meets industry standards.
7.What is the process for return or replacement of SMF20A?
All SMF20A units undergo pre-shipment inspection (PSI). If there is an issue with SMF20A, 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 SMF20A part is unused and in its original packaging.
Return procedure for SMF20A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF20A Tags
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