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Taiwan Semiconductor Corporation SMF51A
- Part No.:
- SMF51A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF51A.pdf
- Description:
- TVS DIODE 51VWM 82.4VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:8,379
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Product details
Overview
SMF51A 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 51 V working stand-off voltage (VWM), 56.7–62.7 V breakdown voltage (VBR), 82.4 V clamping voltage (VC) at 2.4 A peak pulse current, and 200 W peak pulse power (10/1000 µs). It is used in automotive lighting control modules to protect CAN transceiver inputs from load-dump-induced transients.
For engineers reviewing the SMF51A datasheet, SMF51A pinout, SMF51A application, or SMF51A equivalent, key selection criteria include clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b, low leakage (<1 µA @ 51 V), SOD-123W package compatibility with automated placement, and junction temperature rating up to +175 °C.
Technical Context
The SMF51A operates as a unidirectional avalanche diode, conducting only in reverse bias above its breakdown threshold to clamp transient overvoltages. Its glass-passivated junction ensures stable VBR tolerance (±5%) and low leakage, while its thermal design supports 33 °C/W junction-to-lead resistance on standard PCB copper pads.
It meets ISO 7637-2 immunity requirements for automotive electronics, delivering consistent clamping across -55 °C to +175 °C operating range. The device is rated for non-repetitive 10/1000 µs surges up to 200 W and exhibits typical IR <1 µA at 10 V above VWM - critical for low-power sensor rail protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - maximum continuous reverse voltage before clamping begins; sets minimum system operating margin |
| VBR min/max | 56.7 V / 62.7 V - guaranteed breakdown window at 1 mA test current; defines turn-on consistency |
| VC @ IPPM | 82.4 V at 2.4 A - clamping voltage during 10/1000 µs surge; determines protected IC's voltage stress limit |
| PPPM | 200 W - peak pulse power handling (10/1000 µs); qualifies for ISO 7637-2 Pulse 1 & 2b |
| IR @ VWM | <1 µA - reverse leakage at rated stand-off; ensures minimal quiescent power loss in battery systems |
| TJ max | +175 °C - maximum junction temperature; enables under-hood automotive deployment without derating |
| RθJL | 33 °C/W - junction-to-lead thermal resistance on 5 mm × 5 mm Cu pad; informs PCB copper area requirements |
Pinout & Package
Package: SOD-123W - surface-mount, single-diode, cathode-banded case with matte tin-plated leads compliant with J-STD-002 solderability and JESD 201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional TVS configuration |
| Cathode | Clamping terminal | Connected to protected line (e.g., CAN_H); conducts avalanche current when line exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures ±5% VBR tolerance and long-term stability under thermal cycling and humidity |
| Low IR <1 µA @ VWM | Minimizes standby current draw in always-on automotive modules (e.g., body control units) |
| ISO 7637-2 compliance | Validated for Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (ESD-like fast edges) |
| SOD-123W mechanical robustness | UL 94V-0 molding compound and 0.016 g weight support high-reliability automated assembly and vibration resistance |
| Junction temp range –55°C to +175°C | Enables direct placement near heat sources (e.g., motor drivers) without external thermal shielding |
Applications
| Automotive Lighting Control | Industrial PLC I/O Protection |
|---|---|
Use Scenario: Protecting LED driver ICs and microcontroller GPIOs from load-dump transients during headlamp switching. IC Role / Device Role: Unidirectional TVS placed between supply rail and ground to clamp negative-going spikes and positive overshoots. Use Value: Clamps 82.4 V at 2.4 A, limiting stress on 60 V-rated buck controllers and preserving functional safety integrity per ISO 26262 ASIL-B paths. | Use Scenario: Safeguarding 24 V digital input channels against field-wiring induced surges in factory automation cabinets. IC Role / Device Role: Standoff protection element on optocoupler input side, absorbing repetitive 1 kV/500 A transients per IEC 61000-4-5 Level 3. Use Value: 200 W peak power rating and 33 °C/W RθJL allow sustained operation without thermal runaway during frequent surge events. |
| Automotive Body Control Module | Smart Sensor Power Rail Protection |
Use Scenario: Shielding LIN bus transceivers and power management ICs from battery line disturbances during cold-crank and jump-start conditions. IC Role / Device Role: Primary overvoltage clamp on 12 V main rail upstream of LDOs and CAN/LIN PHYs. Use Value: 51 V VWM provides sufficient margin above nominal 12 V system while enabling fast response to 100 V+ transients per ISO 7637-2 Pulse 2a. | Use Scenario: Securing ultra-low-power MEMS pressure sensors powered from coin-cell or energy-harvesting sources. IC Role / Device Role: Low-leakage transient suppressor on VDD line, preventing latch-up during ESD contact discharge. Use Value: Sub-1 µA IR at 51 V preserves battery life over multi-year deployments; SOD-123W footprint minimizes board area in space-constrained IoT nodes. |
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 SMAJ51A | Same SOD-123 package, identical VWM (51 V), but higher VC = 87.1 V at 2.3 A; 175 W PPPM rating | Marginally lower clamping performance; less suitable for 60 V-rated ICs with tight voltage headroom | Select SMF51A when clamping voltage ≤82.4 V is required to meet IC absolute maximum ratings |
| Vishay SMA6J51A | Same VWM and VC (82.4 V), but rated for 600 W PPPM (10/1000 µs); larger SMC package (7.11 × 6.22 mm) | Higher surge capacity but incompatible with SOD-123W layout; requires PCB redesign and increased board area | Choose SMF51A for space-constrained designs where 200 W surge immunity suffices and SOD-123W footprint is fixed |
Compared with SMAJ51A and SMA6J51A, the SMF51A delivers optimal balance of low clamping voltage, SOD-123W compactness, and automotive-grade reliability - making it preferred for cost-sensitive, space-limited 12 V/24 V ECUs where ISO 7637-2 Pulse 1/2b compliance is mandatory.
Availability
SMF51A is available at Aetrix Electronics and suitable for automotive lighting control, industrial PLC I/O protection, and smart sensor power rail protection requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMF51A 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, serving global automotive, industrial, and consumer markets since 1979.
The SMF51A belongs to TSC's SMFxxA series of unidirectional TVS diodes engineered specifically for ISO 7637-2-compliant automotive electronics and high-reliability industrial power rail protection.
FAQ
What is the clamping voltage of SMF51A and how is it measured?
The SMF51A has a maximum clamping voltage (VC) of 82.4 V at a peak pulse current (IPPM) of 2.4 A, tested with a 10/1000 µs waveform per IEC 61000-4-5. This value represents the upper voltage limit imposed on the protected circuit during a standardized surge event. The measurement is performed under controlled lab conditions using calibrated surge generators and high-bandwidth oscilloscopes. For reliable system-level protection, designers must ensure downstream ICs have absolute maximum ratings exceeding 82.4 V.
Does SMF51A meet automotive transient immunity standards?
Yes, the SMF51A is explicitly validated to meet ISO 7637-2 requirements for Pulses 1, 2a, 2b, 3a, and 3b - covering load-dump, inductive switching, and ESD-like transients common in 12 V and 24 V vehicle electrical systems. Its 200 W peak pulse power rating, low clamping voltage, and –55 °C to +175 °C operating range align with AEC-Q101 stress test profiles. Taiwan Semiconductor provides test reports confirming compliance, not just theoretical capability.
What is the marking code for SMF51A and how is it read on the device?
The SMF51A is marked on the cathode band side with the code "2W051", followed by a date code (e.g., "2325") and factory identifier. "2W051" uniquely identifies the 51 V variant within the SMFxxA family and distinguishes it from adjacent variants like SMF48A ("2W048") or SMF54A ("2W054"). The cathode band indicates the polarity: the banded end is the cathode and must be connected to the line being protected. No additional decoding or interpretation is required.
Can SMF51A replace SMF5.0A in a 5 V logic rail application?
No, SMF51A is not suitable for 5 V logic rail protection because its 51 V working stand-off voltage (VWM) is far above the 5 V system level - it will not activate during typical 5 V overvoltage events. Using SMF51A on a 5 V rail leaves the circuit unprotected until transients exceed ~56.7 V, well beyond safe operating limits for 5 V ICs. For 5 V applications, SMF5.0A (VWM = 5 V) or SMF6.0A (VWM = 6 V) must be selected to ensure timely clamping below 7 V.
What is the thermal resistance profile of SMF51A and how does it affect PCB layout?
The SMF51A has a junction-to-lead thermal resistance (RθJL) of 33 °C/W and junction-to-ambient (RθJA) of 100 °C/W when mounted on a 5 mm × 5 mm copper pad per JEDEC standards. To maintain safe junction temperatures under repeated surge duty cycles, designers must provide ≥5 mm² of 1 oz. copper connected directly to both terminals - especially the cathode - and avoid narrow traces or thermal isolation. Insufficient copper area causes localized heating that degrades clamping consistency and shortens lifetime.
SMF51A 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):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 2.4A
- 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
SMF51A FAQ
1.How can I place an order for SMF51A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF51A 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 SMF51A reliable?
The price and inventory of SMF51A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF51A is usually 5 days.
3.What payment methods are accepted for SMF51A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF51A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF51A?
SMF51A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF51A 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 SMF51A?
For technical support, including SMF51A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF51A requirements.
6.How does Aetrix verify that SMF51A is sourced from the original manufacturer or authorized distributors?
All SMF51A 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 SMF51A meets industry standards.
7.What is the process for return or replacement of SMF51A?
All SMF51A units undergo pre-shipment inspection (PSI). If there is an issue with SMF51A, 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 SMF51A part is unused and in its original packaging.
Return procedure for SMF51A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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