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Taiwan Semiconductor Corporation SMF85A
- Part No.:
- SMF85A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF85A.pdf
- Description:
- TVS DIODE 85VWM 137VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:9,673
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Product details
Overview
SMF85A 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 85V working stand-off voltage (VWM), 94.4–104V breakdown voltage (VBR), 137V clamping voltage (VC) at 1.3A peak pulse current, and 200W peak pulse power (10/1000μs). It is commonly used in automotive body electronics and industrial I/O protection.
For engineers reviewing the SMF85A datasheet, SMF85A pinout, SMF85A application, or SMF85A equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b, low leakage (<1μA @ 85V), SOD-123W package compatibility with automated placement, and thermal resistance (RθJA = 100°C/W) for PCB-level thermal design.
Technical Context
The SMF85A operates as a unidirectional avalanche diode, conducting only in reverse bias above its breakdown threshold to shunt transient energy to ground. Its glass-passivated junction ensures stable VBR tolerance (±5%) and low leakage, while its SOD-123W package supports high thermal dissipation (RθJL = 33°C/W) on standard FR-4 PCBs with 5mm × 5mm copper pads.
It meets ISO 7637-2 immunity requirements for automotive electronics, delivering reliable clamping during load-dump and inductive switching transients. The device is rated for junction temperatures from –55°C to +175°C and has moisture sensitivity level 1 per J-STD-020 - suitable for standard reflow without dry-pack handling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 85 V - Maximum continuous reverse operating voltage before clamping begins |
| VBR min/max | 94.4 V / 104 V - Breakdown occurs within this range at 1 mA test current; defines turn-on threshold consistency |
| VC @ IPPM | 137 V - Clamped voltage at 1.3 A peak pulse current (10/1000μs); determines protected circuit's maximum overvoltage stress |
| PPPM | 200 W - Peak pulse power handling capability; enables robust protection against fast, high-energy transients |
| IR @ VWM | <1 μA - Reverse leakage at rated stand-off voltage; ensures minimal standby power loss and signal integrity |
| TJ max | +175 °C - Maximum junction temperature; supports operation in under-hood automotive or high-ambient industrial environments |
| Package | SOD-123W - Surface-mount outline with enhanced thermal pad; compatible with automated pick-and-place and reflow soldering |
Pinout & Package
SOD-123W is a single-diode, two-terminal surface-mount package with cathode indicated by a band. Leads are matte tin-plated and solderable per J-STD-002. 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 return path; completes conduction loop during clamping |
| Cathode | Protected line input | Connected to the line being protected (e.g., 12V supply rail); reverse-biased during normal operation |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR tolerance (±5%) 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/coupled noise) |
| Low IR <1 μA @ VWM | Minimizes quiescent current draw and avoids false triggering in high-impedance sensing circuits |
| Moisture sensitivity level 1 | Eliminates baking requirement prior to reflow; simplifies manufacturing and reduces process cost |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for environmentally restricted markets |
Applications
| Automotive Body Control Module (BCM) Power Input Protection | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: Protecting 12V supply rails in BCMs against load-dump transients up to ±100V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between VBAT and GND, clamping surges before they reach LDOs and microcontrollers. Use Value: Limits voltage seen by downstream ICs to ≤137V during 200W transients, preventing latch-up or permanent damage. | Use Scenario: Safeguarding 24V digital input channels in programmable logic controllers exposed to field-wiring inductive kickback. IC Role / Device Role / Timing Role: Standoff protection device mounted at connector entry point, absorbing repetitive 10/1000μs pulses up to 1.3A. Use Value: Maintains signal integrity by holding leakage below 1μA at 24V nominal, while clamping spikes to safe levels for optocoupler inputs. |
| LED Driver Supply Line Protection | Automotive Infotainment USB Port ESD Suppression |
Use Scenario: Shielding constant-current LED driver ICs from voltage reversals and switching noise in vehicle lighting systems. IC Role / Device Role / Timing Role: Reverse-polarity and surge protector on the input side of buck/boost drivers, placed upstream of input capacitors. Use Value: Withstands 175W pulses (VWM ≥60V derating) and operates up to +175°C ambient - matching under-hood thermal demands. | Use Scenario: Secondary-level ESD protection for USB VBUS lines in head units subjected to IEC 61000-4-2 contact discharge (±8 kV). IC Role / Device Role / Timing Role: Coordinated clamping device working with primary polymer PTC and capacitor filtering to meet system-level immunity targets. Use Value: Delivers sub-1μA leakage at 5V standby, avoiding false enumeration, while clamping 10/1000μs ESD events to <137V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ85A | Higher PPPM (600W), larger SMB package (vs. SOD-123W), RθJA ≈ 50°C/W | Better suited for higher-energy transients but requires more board area and different thermal layout | Select when >200W pulse handling is required and space allows SMB footprint |
| P4SMA85A | Same VWM/VBR/VC specs, DO-214AC package, lower PPPM (400W), RθJA ≈ 65°C/W | Compatible with through-hole or larger SMT assembly; less optimized for ultra-compact layouts | Choose if legacy DO-214AC compatibility or higher surge margin than SMF series is needed |
Compared with SMBJ85A and P4SMA85A, the SMF85A offers the smallest footprint (SOD-123W) and lowest profile for space-constrained automotive and portable industrial designs, while maintaining full ISO 7637-2 compliance - making it optimal where board area and reflow compatibility are prioritized over absolute peak power rating.
Availability
SMF85A is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O modules, LED driver power stages, and infotainment USB protection requiring stable component supply across production lifecycles.
Supply support for SMF85A 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 SMF85A belongs to TSC's SMF-series unidirectional TVS family, engineered specifically for high-reliability, surface-mount surge protection in automotive and industrial environments where compact size, low leakage, and ISO 7637-2 compliance are mandatory.
FAQ
What is the clamping voltage of the SMF85A under standard test conditions?
The SMF85A has a maximum clamping voltage (VC) of 137 V when subjected to a 10/1000μs waveform at a peak pulse current (IPPM) of 1.3 A. This value is measured per JEDEC standards and reflects the upper limit of voltage imposed on the protected circuit during transient events. The SMF85A maintains this clamping performance across its specified operating temperature range (–55°C to +175°C), ensuring consistent protection behavior in harsh environments.
Does the SMF85A meet automotive surge immunity standards?
Yes, the SMF85A meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (coupled electrical fast transients). Its 200W peak pulse power rating, low clamping voltage, and stable VBR tolerance enable reliable compliance in 12V and 24V automotive subsystems. The SMF85A is widely deployed in BCMs, lighting control units, and infotainment power supplies for this reason.
What is the marking code for the SMF85A on the device body?
The SMF85A is marked on the device body with the code "2W085", followed by a date code and factory identifier. This marking appears on the cathode-banded side of the SOD-123W package and aligns with Taiwan Semiconductor's standardized coding scheme for the SMF-series. The "2W" prefix denotes the SMF family, and "085" indicates the 85V working stand-off voltage rating.
Can the SMF85A be used in bidirectional configurations?
No, the SMF85A is a unidirectional TVS diode and is not rated for bidirectional operation. It conducts only in reverse bias above its breakdown voltage and blocks forward current like a standard rectifier. For bidirectional protection (e.g., AC lines or data lines with polarity reversal), a dedicated bidirectional part such as SMBJ85CA or an external series pair of unidirectional devices would be required - the SMF85A alone does not provide symmetrical clamping.
What is the thermal resistance of the SMF85A when mounted on a standard PCB?
When mounted on a standard FR-4 PCB with a 5 mm × 5 mm copper pad per JEDEC test conditions, the SMF85A exhibits a junction-to-ambient thermal resistance (RθJA) of 100°C/W and a junction-to-lead resistance (RθJL) of 33°C/W. These values confirm its suitability for high-temperature environments up to +175°C junction, provided adequate copper area and airflow are maintained - critical for under-hood automotive applications where the SMF85A is frequently deployed.
SMF85A 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):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 1.3A
- 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
SMF85A FAQ
1.How can I place an order for SMF85A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF85A 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 SMF85A reliable?
The price and inventory of SMF85A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF85A is usually 5 days.
3.What payment methods are accepted for SMF85A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF85A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF85A?
SMF85A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF85A 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 SMF85A?
For technical support, including SMF85A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF85A requirements.
6.How does Aetrix verify that SMF85A is sourced from the original manufacturer or authorized distributors?
All SMF85A 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 SMF85A meets industry standards.
7.What is the process for return or replacement of SMF85A?
All SMF85A units undergo pre-shipment inspection (PSI). If there is an issue with SMF85A, 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 SMF85A part is unused and in its original packaging.
Return procedure for SMF85A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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