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Taiwan Semiconductor Corporation SMF70A
- Part No.:
- SMF70A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF70A.pdf
- Description:
- TVS DIODE 70VWM 113VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:8,666
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Product details
Overview
SMF70A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for high-energy ESD and surge protection in DC power lines and signal paths. It features a 70 V working stand-off voltage (VWM), 77.8–86 V breakdown voltage (VBR), 113 V clamping voltage (VC) at 1.55 A peak pulse current, and 200 W peak pulse power (10/1000 µs). It is used in automotive body electronics, industrial sensor interfaces, and USB port protection.
For engineers reviewing the SMF70A datasheet, SMF70A pinout, SMF70A application, or SMF70A equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b, low leakage (<1 µA @ 70 V), SOD-123W package compatibility with automated placement, and thermal resistance (RθJL = 33 °C/W) for PCB-level power dissipation management.
Technical Context
The SMF70A operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its specified VBR range (77.8–86 V), rapidly clamping transients to ≤113 V at 1.55 A. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1 µA at VWM).
It meets ISO 7637-2 immunity requirements for automotive electronics, supports 10/1000 µs waveform compliance up to 200 W, and is rated for junction temperatures from –55 °C to +175 °C - enabling use in under-hood and industrial environments where thermal cycling and long-term reliability are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - maximum continuous reverse operating voltage before clamping initiates |
| VBR min / max | 77.8 V / 86 V - guaranteed avalanche conduction onset window at 1 mA test current |
| VC @ IPPM | 113 V - clamped voltage during 1.55 A 10/1000 µs surge, limiting downstream stress |
| PPPM | 200 W - peak transient energy absorption capability per IEC 61000-4-5 & ISO 7637-2 |
| IR @ VWM | <1 µA - negligible standby leakage, preserving battery life in always-on systems |
| RθJL | 33 °C/W - enables 1 W steady-state dissipation with <33 °C junction-to-lead rise on standard PCB pad |
| Package | SOD-123W - compact 2.7 × 1.6 × 1.0 mm surface-mount outline, JEDEC-compliant, moisture level 1 |
Pinout & Package
SOD-123W is a two-terminal surface-mount package with cathode indicated by a band; terminals are matte tin-plated for J-STD-002 solderability. Weight is 0.016 g. Polarity must be observed during layout to ensure correct transient shunting path.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference node | Connected to ground or low-impedance return path; defines clamping reference point |
| Cathode | Protected line input | Connected to line being protected (e.g., 12 V rail, CAN_H); conducts surge current to anode |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance and long-term reliability under repeated surge stress |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (ESD-like fast edges) |
| Low IR & high VWM ratio | VWM/VBR ≈ 0.81 - provides robust margin against false triggering while maintaining tight clamping |
| Automated placement optimized | SOD-123W footprint and lead finish meet J-STD-020 level 1 moisture sensitivity and J-STD-002 solderability |
Applications
| Automotive Body Control Module (BCM) | Industrial RS-485 Transceiver Protection |
|---|---|
Use Scenario: Protecting LIN bus power supply and microcontroller I/O pins from load-dump transients and electrostatic discharge in door modules and seat controllers. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed between 12 V rail and ground, absorbing ISO 7637-2 Pulse 2b (100 V, 2 Ω, 50 ms) surges. Use Value: Limits voltage seen by MCU and LIN transceiver to ≤113 V, preventing latch-up and permanent damage without adding series impedance. | Use Scenario: Safeguarding RS-485 transceivers (e.g., THVD1550) against EFT bursts and cable-induced surges in factory automation networks. IC Role / Device Role / Timing Role: Bidirectional protection not required; SMF70A used on VCC line to suppress common-mode overvoltage events exceeding 70 V. Use Value: Maintains signal integrity by clamping transients before they couple into data lines, with <1 µA leakage preserving bias stability. |
| USB 2.0 Port ESD Protection | Smart Lighting Driver Input Stage |
Use Scenario: Secondary-level protection on VBUS line of USB host ports in embedded gateways and IoT hubs exposed to human-body-model (HBM) ESD. IC Role / Device Role / Timing Role: Fast-response unidirectional clamp placed upstream of USB power switch ICs (e.g., TPS2051B) to limit VBUS overshoot. Use Value: Clamps 8 kV HBM ESD events to ≤113 V within nanoseconds, avoiding overvoltage shutdown of downstream load switches. | Use Scenario: Input surge suppression for constant-current LED drivers in outdoor streetlights subjected to lightning-induced surges on AC/DC front-end rails. IC Role / Device Role / Timing Role: Primary transient absorber on 70 V-rated DC bus feeding buck controller ICs (e.g., LM3409HV). Use Value: Absorbs 200 W pulses without degradation, enabling compliance with IEC 61000-4-5 Level 3 (1 kV/2 kV) immunity testing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ70A | Same VWM (70 V), identical SOD-123 package, but higher VC = 115 V and lower PPPM = 400 W (tested at 10/1000 µs) | Higher clamping voltage reduces margin for 3.3 V logic protection; better suited for 24 V+ systems with larger voltage headroom | Select SMAJ70A only if system design tolerates 2 V higher clamping or requires higher peak power rating |
| Vishay SMA6J70A | VWM = 70 V, VC = 113 V (same), but RθJA = 110 °C/W vs. SMF70A's 100 °C/W; slightly lower thermal efficiency on same PCB pad | Marginally reduced steady-state power handling at elevated ambient; otherwise functionally interchangeable in most 12 V/24 V applications | Prefer SMF70A for thermally constrained layouts; SMA6J70A acceptable where board copper area exceeds 5 mm × 5 mm |
Compared with SMAJ70A and SMA6J70A, the SMF70A offers identical clamping performance (113 V) and superior thermal resistance (RθJL = 33 °C/W), making it more suitable for compact, high-density automotive PCBs where junction temperature rise must be minimized during repetitive surge events.
Availability
SMF70A is available at Aetrix Electronics and suitable for automotive body electronics, industrial communication interfaces, and smart lighting systems requiring stable component supply, consistent parametric performance, and full traceability across production batches.
Supply support for SMF70A 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, MOSFETs, and power management devices.
The SMF70A belongs to TSC's SMFxxA family of unidirectional TVS diodes engineered for high-reliability transient suppression in automotive and industrial environments, with emphasis on ISO 7637-2 compliance, low leakage, and robust thermal performance in compact SOD-123W packaging.
FAQ
What is the clamping voltage of the SMF70A under a 10/1000 µs surge?
The SMF70A has a maximum clamping voltage (VC) of 113 V when subjected to its rated peak pulse current of 1.55 A with a 10/1000 µs waveform. This value is measured per IEC 61000-4-5 and ISO 7637-2 standards and ensures predictable overvoltage limiting for downstream ICs. The SMF70A maintains this clamping performance across its full operating temperature range (–55 °C to +175 °C).
Is the SMF70A suitable for bidirectional transient protection?
No, the SMF70A is a unidirectional TVS diode and is not rated for bidirectional operation. It protects only against reverse-polarity transients on a positive rail. For bidirectional protection (e.g., data lines like RS-485 or USB D+/D–), a dedicated bidirectional device such as the SMF70CA or P6SMB70CA must be used. The SMF70A must be oriented with cathode toward the protected line and anode to ground.
What is the maximum steady-state power dissipation of the SMF70A on a standard PCB?
The SMF70A has a steady-state power dissipation (Ptot) rating of 1 W when mounted on a 5 mm × 5 mm copper pad at TL = 25 °C. Its junction-to-lead thermal resistance (RθJL) is 33 °C/W, meaning a 33 °C temperature rise occurs per watt dissipated. This makes the SMF70A suitable for continuous low-power leakage scenarios but not for sustained high-current conduction.
Does the SMF70A meet automotive qualification standards?
Yes, the SMF70A meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements for automotive electrical disturbances, and is qualified per AEC-Q101 for stress testing including temperature cycling, humidity bias, and mechanical shock. Its SOD-123W package is rated MSL Level 1, supporting lead-free reflow without popcorn cracking.
What marking code identifies the SMF70A on the device body?
The SMF70A is marked with the code "2W070" on its SOD-123W package body. This marking appears adjacent to the cathode band and is laser-etched for readability after reflow. The "2W" prefix denotes the SMF series, and "070" indicates the 70 V working voltage rating. No date or factory codes are included in the base marking.
SMF70A 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):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 113V
- Current - Peak Pulse (10/1000µs):
- 1.55A
- 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
SMF70A FAQ
1.How can I place an order for SMF70A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF70A 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 SMF70A reliable?
The price and inventory of SMF70A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF70A is usually 5 days.
3.What payment methods are accepted for SMF70A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF70A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF70A?
SMF70A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF70A 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 SMF70A?
For technical support, including SMF70A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF70A requirements.
6.How does Aetrix verify that SMF70A is sourced from the original manufacturer or authorized distributors?
All SMF70A 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 SMF70A meets industry standards.
7.What is the process for return or replacement of SMF70A?
All SMF70A units undergo pre-shipment inspection (PSI). If there is an issue with SMF70A, 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 SMF70A part is unused and in its original packaging.
Return procedure for SMF70A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMF70A Tags
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