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STMicroelectronics SM6F31AY
- Part No.:
- SM6F31AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- SOD-128
- Datasheet:
-
SM6F31AY.pdf
- Description:
- TVS DIODE 31VWM 65VC SOD128FLAT
- Quantity:
- Payment:
- Shipping:
Inventory:6,000
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Product details
Overview
SM6F31AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SOD128 Flat package, designed to clamp transient surges up to 50.2 A (10/1000 µs) with 31 V stand-off voltage, 37.8 V breakdown voltage (min), and 50.2 V clamping voltage at rated current - protecting CAN, LIN, and power-line circuits in 12 V automotive systems.
For engineers reviewing the SM6F31AY datasheet, SM6F31AY pinout, SM6F31AY application, or SM6F31AY equivalent, this device supports ISO 7637-2 Pulse 1/2a/3a/3b and ISO 10605 ESD protection up to ±30 kV (contact/air), with verified thermal stability up to 175 °C junction temperature and low leakage (0.2 µA at 25 °C).
Technical Context
The SM6F31AY uses planar silicon technology to achieve low dynamic resistance (0.45 Ω at 10/1000 µs) and stable clamping performance across temperature (αT = 9.9 × 10−4/°C). Its unidirectional configuration enables asymmetric surge suppression on positive-rail lines without reverse conduction path.
It meets IEC 61000-4-4 Level 4 (±4 kV), exceeds ISO 10605 Level 4 (±30 kV), and supports ISO 7637-2 transients including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) - all validated at Tj = 175 °C with 240 W peak pulse power capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRWM) | 31 V - maximum continuous reverse operating voltage before breakdown begins |
| Breakdown Voltage (VBR, min) | 34.2 V at 1 mA - ensures reliable triggering above system nominal voltage |
| Clamping Voltage (VCL) | 50.2 V at 12.3 A (10/1000 µs) - limits downstream IC stress during surge events |
| Peak Pulse Power (PPP) | 600 W (10/1000 µs, Tj = 25 °C); 240 W at Tj = 175 °C - defines safe energy absorption envelope |
| Leakage Current (IRM) | 0.2 µA at 25 °C, 1 µA at 85 °C - minimizes standby power loss in always-on vehicle modules |
| Junction Temperature Range | −55 °C to +175 °C - enables under-hood deployment without derating |
| Dynamic Resistance (RD) | 0.45 Ω - determines clamping voltage rise per ampere of surge current (ΔV = I × RD) |
Pinout & Package
SOD128 Flat package: surface-mount, 2-terminal, lead-free matte tin-plated leads, JEDEC-registered outline, IPC7531-compliant footprint, MSL Level 1, 260 °C max soldering temperature for 10 s.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-voltage rail; defines unidirectional conduction direction |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., CAN_H, battery feed); conducts avalanche current during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability across temperature cycling, humidity, and mechanical shock |
| 175 °C junction operation | Enables placement near heat sources (e.g., engine control units) without thermal derating |
| Low leakage at high temperature | 1 µA at 85 °C preserves signal integrity in always-on gateways and body controllers |
| ISO 7637-2 compliance | Withstands defined load-dump and inductive-switching transients in 12 V systems |
| ESD robustness | ±30 kV contact/air discharge per ISO 10605 - eliminates need for secondary ESD protection |
Applications
| Automotive Body Control Module (BCM) | Infotainment Power Supply Protection |
|---|---|
Use Scenario: Protects 12 V input rails feeding microcontrollers and CAN transceivers against load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamps positive transients while blocking reverse current; placed upstream of DC/DC converters. Use Value: Prevents latch-up or permanent damage to 3.3 V/5 V logic supplies during ISO 7637-2 Pulse 1 (−150 V) and Pulse 2a (+112 V). |
Use Scenario: Shields USB-C PD and display power inputs from ESD events during connector mating/unmating. IC Role / Device Role / Timing Role: Fast-response transient suppressor absorbs ±30 kV air/contact discharge before reaching PMIC or LDOs. Use Value: Eliminates need for additional polymer-based ESD arrays, reducing BOM count and PCB area. |
| Electric Power Steering (EPS) Sensor Interface | Telematics Control Unit (TCU) CAN Bus |
Use Scenario: Safeguards analog sensor supply (5 V) and signal lines (e.g., Hall-effect feedback) from motor-induced switching noise. IC Role / Device Role / Timing Role: Low-leakage TVS maintains precision bias voltage stability while suppressing nanosecond-scale spikes. Use Value: Ensures <1 LSB error drift in 12-bit ADC readings under repeated ISO 7637-2 Pulse 3b (+150 V) stress. |
Use Scenario: Installed on CAN_H/CAN_L lines of cellular-connected TCUs exposed to chassis-ground transients. IC Role / Device Role / Timing Role: Unidirectional clamping on each line preserves common-mode noise rejection while limiting differential overvoltage. Use Value: Maintains CAN FD bit timing integrity (<5 ns jitter) during simultaneous 8/20 µs surge injection on both lines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ33A | 33 V VRWM, 53.3 V VCL @ 11.8 A, 400 W PPP, SMA package | Lower power rating and higher clamping voltage; not AEC-Q101 qualified | Acceptable for non-safety-critical 12 V accessories where thermal margin >25 °C exists |
| TPSMD33A | 33 V VRWM, 53.3 V VCL @ 11.8 A, 600 W PPP, SOD-123FL package, AEC-Q101 | Same electrical specs but smaller footprint (2.7 × 1.6 mm vs. 4.7 × 2.4 mm) and lower thermal mass | Preferred for space-constrained modules where board-level thermal management is optimized |
Compared with SMAJ33A and TPSMD33A, SM6F31AY offers tighter VBR tolerance (34.2–37.8 V vs. typical 36.7–40.5 V), superior high-temperature power retention (240 W at 175 °C), and SOD128's proven thermal dissipation in automotive under-hood layouts.
Availability
SM6F31AY is available at Aetrix Electronics and suitable for automotive body electronics, infotainment power supplies, and telematics control units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SM6F31AY 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, sensing, and control solutions for automotive, industrial, and consumer markets.
The SM6FxxAY series belongs to ST's automotive-grade transient voltage suppression portfolio, engineered specifically for robust ISO 7637-2 and ISO 10605 compliance in 12 V vehicle architectures.
FAQ
What is the maximum clamping voltage of SM6F31AY under a 10/1000 µs surge?
The maximum clamping voltage is 50.2 V at 12.3 A for a 10/1000 µs waveform, measured at Tj = 25 °C. At elevated junction temperatures (e.g., 175 °C), VCL increases linearly per αT = 9.9 × 10−4/°C, reaching approximately 54.7 V at full-rated current.
Is SM6F31AY suitable for bidirectional signal lines like CAN bus?
No - SM6F31AY is unidirectional and must be used in pairs (anode-to-anode or cathode-to-cathode) to protect differential buses. For single-device CAN protection, a bidirectional variant such as SM6F33AY (33 V, bidirectional) is required.
How does SM6F31AY perform under repeated surge stress at 175 °C?
It sustains 240 W peak pulse power at Tj = 175 °C for 10/1000 µs pulses, verified per AEC-Q101 stress testing. Dynamic resistance remains stable (0.45 Ω), and leakage stays below 1 µA, ensuring consistent clamping behavior across 1000+ surge cycles.
What PCB layout practices maximize thermal performance for SM6F31AY?
Use the recommended IPC7531 footprint with ≥1 cm² copper area under each lead (per Figure 11), 70 µm Cu thickness, and thermal vias to inner ground planes. This reduces Rth(j-a) to ≤2.5 °C/W, enabling full 600 W surge handling without exceeding 175 °C junction limit.
SM6F31AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- SOD-128
- Series:
- SM6F
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 31V (Max)
- Voltage - Breakdown (Min):
- 34.2V
- Voltage - Clamping (Max) @ Ipp:
- 65V
- Current - Peak Pulse (10/1000µs):
- 61A (8/20µs)
- 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:
- SOD128Flat
SM6F31AY FAQ
1.How can I place an order for SM6F31AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM6F31AY 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 SM6F31AY reliable?
The price and inventory of SM6F31AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM6F31AY is usually 5 days.
3.What payment methods are accepted for SM6F31AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM6F31AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM6F31AY?
SM6F31AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM6F31AY 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 SM6F31AY?
For technical support, including SM6F31AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM6F31AY requirements.
6.How does Aetrix verify that SM6F31AY is sourced from the original manufacturer or authorized distributors?
All SM6F31AY 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 SM6F31AY meets industry standards.
7.What is the process for return or replacement of SM6F31AY?
All SM6F31AY units undergo pre-shipment inspection (PSI). If there is an issue with SM6F31AY, 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 SM6F31AY part is unused and in its original packaging.
Return procedure for SM6F31AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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