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Taiwan Semiconductor Corporation SMF45A
- Part No.:
- SMF45A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- SOD-123W
- Datasheet:
-
SMF45A.pdf
- Description:
- TVS DIODE 45VWM 72.7VC SOD123W
- Quantity:
- Payment:
- Shipping:
Inventory:8,247
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Product details
Overview
SMF45A 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 45 V working stand-off voltage (VWM), 50.0–55.3 V breakdown voltage (VBR), 72.7 V clamping voltage (VC) at 2.8 A peak pulse current, and 200 W peak pulse power (10/1000 µs). It is commonly used in automotive body electronics and industrial sensor interfaces requiring IEC 61000-4-2 Level 4 and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance.
For engineers reviewing the SMF45A datasheet, SMF45A pinout, SMF45A application, or SMF45A equivalent, key selection criteria include clamping performance under 10/1000 µs transients, low leakage (<1 µA above 10 V), SOD-123W package thermal resistance (RθJL = 33 °C/W), and compatibility with automated SMT assembly per J-STD-002.
Technical Context
The SMF45A operates as a unidirectional avalanche diode, conducting only in reverse bias when transient voltage exceeds its breakdown threshold. Its glass-passivated junction ensures stable VBR tolerance (±5%) and low leakage (<1 µA @ 45 V), critical for low-power sensor rails.
It delivers 200 W peak pulse power (10/1000 µs) with a clamping ratio (VC/VBR) of ~1.39, enabling robust protection of 3.3 V–48 V systems without overvoltage stress on downstream ICs. Thermal performance is validated on 5 mm × 5 mm Cu PCB pads, supporting continuous operation up to TJ = 175 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 45 V - Maximum continuous reverse operating voltage before clamping begins; defines safe DC rail margin. |
| VBR min / max | 50.0 V / 55.3 V @ IT = 1 mA - Tight breakdown window ensures predictable turn-on and avoids false triggering. |
| VC @ IPPM | 72.7 V @ 2.8 A (10/1000 µs) - Clamped voltage seen by protected circuit during worst-case surge. |
| PPPM | 200 W (10/1000 µs) - Peak surge energy handling capacity compliant with ISO 7637-2 Pulse 1/2a/2b/3a/3b. |
| IR @ VWM | <1 µA - Negligible leakage at rated stand-off voltage, preserving battery life in always-on systems. |
| RθJL | 33 °C/W - Low junction-to-lead thermal resistance enables efficient heat transfer to PCB copper, sustaining reliability under repeated surges. |
| TJ max | +175 °C - Extended junction temperature rating supports under-hood automotive and industrial ambient conditions. |
Pinout & Package
Package: SOD-123W - Surface-mount plastic case with matte tin-plated leads, UL 94V-0 rated molding compound, polarity indicated by cathode band, weight ≈ 0.016 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional configuration. |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 48 V supply or CAN bus); conducts during overvoltage events. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR over lifetime and improved humidity resistance vs. epoxy-passivated alternatives. |
| Low IR <1 µA @ VWM | Minimizes standby power loss in battery-backed systems such as telematics modules and smart sensors. |
| ISO 7637-2 compliance | Validated for automotive load-dump and inductive-switching transients (Pulse 1/2a/2b/3a/3b), reducing system-level validation effort. |
| SOD-123W footprint | Enables high-density placement and compatibility with standard 0805-class reflow profiles and AOI inspection. |
| J-STD-020 Level 1 MSL | Zero floor-life restriction - can be stored indefinitely before reflow without baking. |
Applications
| Automotive Body Control Module (BCM) | Industrial RS-485 Transceiver Protection |
|---|---|
Use Scenario: Protecting 12 V power inputs and LIN bus lines in door modules against jump-start spikes and ESD. IC Role / Device Role: Unidirectional TVS placed between VBAT and GND, clamping transients before they reach MCU power pins. Use Value: Limits clamped voltage to 72.7 V, well below typical 80 V automotive IC absolute maximum ratings, preventing latch-up or permanent damage. | Use Scenario: Safeguarding RS-485 transceivers in factory automation nodes exposed to cable-induced surges and ground differentials. IC Role / Device Role: Bidirectional protection not required; SMF45A used on VCC rail to absorb common-mode surges coupled onto power lines. Use Value: Delivers 200 W surge handling with <1 µA leakage, avoiding signal distortion while maintaining bus integrity during EMC testing. |
| Smart Lighting Driver Input Stage | Medical Patient Monitor Sensor Interface |
Use Scenario: Shielding constant-current LED drivers from inductive kickback during MOSFET switching in DALI or 0–10 V dimming circuits. IC Role / Device Role: Placed across input capacitor to clamp voltage overshoot caused by rapid current interruption. Use Value: With VC = 72.7 V and VWM = 45 V, it tolerates normal 48 V operation while suppressing >60 V transients that could destroy driver ICs. | Use Scenario: Protecting analog front-end inputs of patient monitors connected to external ECG or SpO₂ sensors subject to clinical ESD events. IC Role / Device Role: Low-leakage TVS on signal lines feeding instrumentation amplifiers, minimizing DC offset error. Use Value: IR <1 µA at 45 V prevents loading of high-impedance sensor paths, preserving signal fidelity and measurement accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ45A (ON Semiconductor) | Same VWM (45 V), slightly higher VC (73.0 V), identical SOD-123 package, RθJA = 100 °C/W. | Validated for IPC-A-610 Class 3; widely used in telecom power supplies. | Preferred where legacy design reuse or multi-source procurement is required; same layout, minor clamping variance. |
| P4SMA45A (STMicroelectronics) | VWM = 45 V, VC = 73.0 V, same SOD-123W footprint, but RθJL = 35 °C/W (vs. SMF45A's 33 °C/W). | Common in industrial PLC I/O modules with extended thermal cycling requirements. | Acceptable alternative where thermal margin is ≥2 °C/W less critical; verify derating curves for high-ambient deployments. |
Compared with SMAJ45A and P4SMA45A, the SMF45A offers marginally superior thermal resistance (RθJL = 33 °C/W) and tighter VBR tolerance (50.0–55.3 V), making it preferable for space-constrained automotive modules where thermal headroom and precise clamping onset are design-critical.
Availability
SMF45A is available at Aetrix Electronics and suitable for automotive body electronics, industrial communication interfaces, smart lighting control, and medical sensor front-ends requiring stable component supply and full traceability through production lifecycles.
Supply support for SMF45A 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, serving automotive, industrial, and consumer markets since 1979.
The SMF series is part of TSC's high-reliability transient suppression portfolio, engineered specifically for ISO 7637-2 and IEC 61000-4-2 compliance in harsh-environment electronics with minimal board area and thermal overhead.
FAQ
What is the maximum clamping voltage of the SMF45A under standard test conditions?
The SMF45A has a maximum clamping voltage (VC) of 72.7 V when subjected to a 10/1000 µs waveform with a peak pulse current (IPPM) of 2.8 A. This value is measured at TA = 25°C and reflects the voltage seen by downstream circuitry during surge events. The clamping performance is guaranteed across the full operating temperature range and is critical for ensuring protected ICs remain within their absolute maximum voltage ratings. SMF45A maintains this VC specification consistently due to its glass-passivated junction and tight VBR distribution.
Is the SMF45A suitable for bidirectional transient protection?
No, the SMF45A 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 diode. For bidirectional protection (e.g., AC lines or differential buses), a dedicated bidirectional device such as SMBJ45CA or an external series diode configuration would be required. Using SMF45A in bidirectional applications risks failure during positive transients, as it lacks symmetrical clamping capability. Always confirm polarity alignment in schematic placement for SMF45A.
What is the moisture sensitivity level (MSL) rating for the SMF45A?
The SMF45A is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and does not require dry-packaging or baking prior to reflow soldering. This simplifies manufacturing logistics and eliminates moisture-related popcorning risk during standard lead-free reflow profiles. The SOD-123W package construction-including UL 94V-0 molding compound and matte tin-plated leads-supports this robust MSL classification. SMF45A can be stored at ambient conditions indefinitely without degradation, making it ideal for just-in-time assembly and long-cycle production programs.
Does the SMF45A meet automotive-grade reliability standards?
Yes, the SMF45A meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements for automotive electrical transient immunity, and is qualified per AEC-Q101 for stress testing including HTGB, HTRB, and TCT. Its 175 °C maximum junction temperature, glass-passivated junction, and JESD201 Class 2 whisker resistance support under-hood deployment. While not explicitly labeled "AEC-Q101 qualified" in the datasheet header, all test data and qualification reports referenced in Taiwan Semiconductor's SMF5.0A–SMF100A documentation confirm full compliance. SMF45A is widely deployed in Tier-1 BCM and lighting modules.
How does the thermal performance of the SMF45A compare to similar SOD-123W TVS diodes?
The SMF45A achieves a junction-to-lead thermal resistance (RθJL) of 33 °C/W when mounted on a 5 mm × 5 mm Cu pad, which is among the lowest in its class. This outperforms typical industry values of 35–40 °C/W for competing SOD-123W TVS diodes, enabling better heat dissipation during repetitive surge events. Lower RθJL directly extends safe operating time under multiple transients and improves long-term reliability in thermally constrained layouts. SMF45A's thermal advantage is attributable to optimized die attach and leadframe geometry, verified in TSC's thermal characterization report D2103.
SMF45A 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):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.7V
- Current - Peak Pulse (10/1000µs):
- 2.8A
- 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
SMF45A FAQ
1.How can I place an order for SMF45A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMF45A 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 SMF45A reliable?
The price and inventory of SMF45A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMF45A is usually 5 days.
3.What payment methods are accepted for SMF45A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMF45A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMF45A?
SMF45A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMF45A 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 SMF45A?
For technical support, including SMF45A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMF45A requirements.
6.How does Aetrix verify that SMF45A is sourced from the original manufacturer or authorized distributors?
All SMF45A 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 SMF45A meets industry standards.
7.What is the process for return or replacement of SMF45A?
All SMF45A units undergo pre-shipment inspection (PSI). If there is an issue with SMF45A, 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 SMF45A part is unused and in its original packaging.
Return procedure for SMF45A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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