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STMicroelectronics SMA6F31AY
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- Part No.:
- SMA6F31AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-221AC, SMA Flat Leads
- Datasheet:
-
SMA6F31AY.pdf
- Description:
- TVS DIODE 31VWM 50.2VC SMAFLAT
- Quantity:
- Payment:
- Shipping:
Inventory:8,850
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Product details
Overview
SMA6F31AY from STMicroelectronics is an AEC-Q101-qualified unidirectional 600 W transient voltage suppressor (TVS) diode designed for automotive power line and signal line surge protection. It features a stand-off voltage (VRM) of 31 V, clamping voltage (VCL) of 50.2 V at 12.3 A (10/1000 µs), dynamic resistance (RD) of 0.45 Ω, and operates up to 175 °C junction temperature - enabling robust protection in engine control units, body electronics, and infotainment power rails.
For engineers reviewing the SMA6F31AY datasheet, SMA6F31AY pinout, SMA6F31AY application, or SMA6F31AY equivalent, this device is selected for ISO 7637-2 Pulse 1 (–150 V), Pulse 3a (–220 V), and ISO 10605 ESD immunity (±30 kV contact/air), with verified low leakage (0.2 μA @ 25 °C) and flat SMA package compatibility with high-density PCB layouts.
Technical Context
This TVS uses planar silicon technology to achieve stable breakdown behavior across –55 °C to +175 °C, with temperature coefficient αT = 9.9 × 10⁻⁴ /°C enabling predictable VBR drift. Its unidirectional configuration supports DC-biased lines where reverse conduction must be blocked during normal operation.
The device delivers 600 W peak pulse power (10/1000 µs) at 25 °C and retains 400 W at Tj = 175 °C, validated per IEC 61000-4-4 Level 4 (±4 kV), ISO 10605 (±30 kV), and ISO 7637-2 transients - including Pulse 1 (VS = –150 V), Pulse 2a (VS = +112 V), Pulse 3a (VS = –220 V), and Pulse 3b (VS = +150 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 31 V - maximum continuous reverse operating voltage before clamping begins; matches 24 V automotive systems with margin. |
| Clamping Voltage (VCL) | 50.2 V at 12.3 A (10/1000 µs) - limits downstream IC voltage stress during ISO 7637-2 Pulse 1 and Pulse 3a events. |
| Peak Pulse Power | 600 W (10/1000 µs) - sustains 12.3 A surge current without failure under standard test conditions. |
| Dynamic Resistance (RD) | 0.45 Ω - determines VCL rise slope (ΔV = RD × ΔI); enables precise clamping predictability in circuit simulation. |
| Leakage Current (IRM) | 0.2 μA @ 25 °C, 1 μA @ 85 °C - ensures minimal standby power loss in always-on vehicle modules. |
| Junction Temperature Range | –55 °C to +175 °C - supports under-hood placement near engines and transmission control units. |
| Package | SMA Flat (DO-214AC) - 1 mm profile, JEDEC-registered outline, IPC7531-compliant footprint for automated assembly. |
Pinout & Package
SMA6F31AY uses the SMA Flat (DO-214AC) surface-mount package: 2.25–2.90 mm length, 5.00–5.35 mm width, 0.90–1.10 mm height, matte tin-plated leads, MSL Level 1, and UL94 V0 flammability rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked band) | Surge current sink terminal | Connected to protected line; conducts during overvoltage to shunt energy to ground. |
| Anode | Reference/ground return path | Typically tied to chassis or system ground; completes clamping loop during transient events. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability across temperature cycling, humidity, and mechanical shock per JESD22 standards. |
| Flat 1 mm profile | Enables use in space-constrained modules (e.g., junction boxes, ADAS ECUs) without compromising thermal performance. |
| ISO 7637-2 compliance | Withstands defined automotive transients: Pulse 1 (–150 V), Pulse 2a (+112 V), Pulse 3a (–220 V), Pulse 3b (+150 V). |
| Low dynamic resistance | 0.45 Ω minimizes clamping voltage overshoot under fast-rising surges, improving protection margin for 3.3 V/5 V logic interfaces. |
| High-temperature operation | Rated for 175 °C junction temperature - supports placement near heat sources without derating or thermal shutdown. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Line |
|---|---|
|
Use Scenario: Protects 12 V supply rail against load dump and alternator-induced spikes during ignition cycles. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery input and DC-DC converter input stage. Use Value: Clamps transients to ≤50.2 V, preventing damage to 40 V-rated buck controllers and ensuring uninterrupted microcontroller operation. |
Use Scenario: Shields LIN physical layer transceivers from ESD and coupled noise on vehicle body wiring harnesses. IC Role / Device Role / Timing Role: Low-capacitance TVS connected between LIN bus and ground, adjacent to transceiver pins. Use Value: Sub-1 nA leakage preserves bus bias integrity; ±30 kV ESD rating exceeds ISO 10605 requirements for interior modules. |
| Infotainment Head Unit USB Power Rail | ADAS Camera Module Power Input |
|
Use Scenario: Guards 5 V USB VBUS line against hot-plug surges and inductive kickback from nearby relays or motors. IC Role / Device Role / Timing Role: TVS mounted at USB connector entry point, upstream of USB power switch and LDO. Use Value: 600 W surge rating handles worst-case 10/1000 µs pulses; 0.45 Ω RD ensures fast response (<1 ns) to sub-microsecond transients. |
Use Scenario: Safeguards 12 V camera power input in rear-view or surround-view systems exposed to harsh under-vehicle environments. IC Role / Device Role / Timing Role: Primary surge clamp on main power feed, paired with ceramic capacitor and ferrite bead. Use Value: 175 °C operation allows direct mounting on camera housing; AEC-Q101 qualification ensures longevity in vibration-prone zones. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMA6F33AY | VRM = 33 V, VCL = 53.3 V @ 11.8 A, RD = 0.512 Ω | Higher stand-off voltage suits 24 V systems with tighter tolerance margins; slightly higher clamping voltage reduces protection margin for 3.3 V logic. | Select when VRM > 31 V is required to avoid false triggering on nominal 24 V rail ripple. |
| SMA6F30AY | VRM = 30 V, VCL = 48.4 V @ 13 A, RD = 0.442 Ω | Lower VRM increases risk of leakage-related power loss in high-temperature environments; tighter clamping benefits low-voltage peripherals. | Prefer for 12 V systems needing lower clamping voltage, provided VRM margin against battery overvoltage is acceptable. |
Compared with SMA6F33AY and SMA6F30AY, SMA6F31AY offers optimal balance between 31 V stand-off margin for 24 V automotive systems and 50.2 V clamping voltage - minimizing both false triggering and downstream component stress without requiring layout redesign.
Availability
SMA6F31AY is available at Aetrix Electronics and suitable for engine control units, body control modules, infotainment head units, and ADAS camera modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SMA6F31AY 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering intelligent power, analog, MEMS, and microcontroller solutions for automotive, industrial, and consumer markets.
SMA6FxxAY belongs to ST's Automotive Transil™ TVS family, engineered specifically for ISO 7637-2 and ISO 10605 compliance in harsh-temperature vehicle subsystems - emphasizing reliability, low leakage, and planar junction stability.
FAQ
What is the maximum clamping voltage of SMA6F31AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 50.2 V at 12.3 A for a 10/1000 µs waveform, measured at 25 °C ambient. This value increases with junction temperature per the coefficient αT = 9.9 × 10⁻⁴ /°C, reaching approximately 52.7 V at Tj = 125 °C using the formula VCL(Tj) = VCL(25°C) × [1 + αT × (Tj − 25)].
Is SMA6F31AY compatible with lead-free reflow soldering processes?
Yes - SMA6F31AY is qualified for lead-free reflow per J-STD-020 MSL Level 1, with a maximum peak temperature of 240–245 °C and 60-second exposure (max 90 s). The recommended profile includes ramp rates of ≤3 °C/s, a liquidus time of 60–90 s, and cooling rate ≤6 °C/s, matching ST's ECOPACK guidelines.
How does the dynamic resistance (RD = 0.45 Ω) affect circuit protection performance?
Dynamic resistance directly determines clamping voltage rise under surge current: VCL = VBR + (RD × IPP). With RD = 0.45 Ω, a 10 A transient adds only 4.5 V above VBR - enabling tighter voltage control than higher-RD alternatives. This improves safety margin for downstream 3.3 V or 5 V ICs while reducing thermal stress on the TVS itself.
Can SMA6F31AY be used in bidirectional configurations?
No - SMA6F31AY is a unidirectional TVS diode, intended for DC-biased lines where reverse conduction must be blocked during normal operation. For AC or bipolar signal lines (e.g., CAN bus), ST recommends bidirectional variants such as SMBJ33CA or SMCJ33CA, which feature symmetrical clamping in both polarities.
SMA6F31AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-221AC, SMA Flat Leads
- Series:
- SMA6F
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 31V
- Voltage - Breakdown (Min):
- 34.2V
- Voltage - Clamping (Max) @ Ipp:
- 50.2V
- Current - Peak Pulse (10/1000µs):
- 12.3A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMAflat
SMA6F31AY FAQ
1.How can I place an order for SMA6F31AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA6F31AY 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 SMA6F31AY reliable?
The price and inventory of SMA6F31AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA6F31AY is usually 5 days.
3.What payment methods are accepted for SMA6F31AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA6F31AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA6F31AY?
SMA6F31AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA6F31AY 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 SMA6F31AY?
For technical support, including SMA6F31AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA6F31AY requirements.
6.How does Aetrix verify that SMA6F31AY is sourced from the original manufacturer or authorized distributors?
All SMA6F31AY 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 SMA6F31AY meets industry standards.
7.What is the process for return or replacement of SMA6F31AY?
All SMA6F31AY units undergo pre-shipment inspection (PSI). If there is an issue with SMA6F31AY, 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 SMA6F31AY part is unused and in its original packaging.
Return procedure for SMA6F31AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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