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STMicroelectronics SM4T12CAY
- Part No.:
- SM4T12CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T12CAY.pdf
- Description:
- TVS DIODE 10VWM 21.7VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,420
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Product details
Overview
SM4T12CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 pulse protection in 12 V battery systems. It features a 12.3 V maximum breakdown voltage (VBR), 21.7 A peak pulse current (IPP) at 8/20 µs, 17 V clamping voltage (VCL), and AEC-Q101 qualification for under-hood reliability.
For engineers reviewing the SM4T12CAY datasheet, SM4T12CAY pinout, SM4T12CAY application, or SM4T12CAY equivalent, this device is selected for robust ESD immunity (±30 kV per ISO 10605), low leakage (≤1 µA at 85 °C), and high junction temperature operation (Tj up to +150 °C) in automotive power line protection.
Technical Context
The SM4T12CAY implements a planar silicon avalanche structure optimized for fast response (<1 ns) to transients defined in ISO 7637-2 (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −200 V; Pulse 3b: +150 V) and electrostatic discharge events per ISO 10605 (150 pF/330 Ω and 330 pF/330 Ω).
Its bidirectional configuration enables symmetrical clamping across both polarities without external polarity management, while its SMA package supports JEDEC-standard PCB mounting and reflow profiles compliant with IPC/JEDEC J-STD-020.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min) | 11.1 V - Ensures reliable conduction onset above normal 12 V system operating voltage |
| VCL @ 8/20 µs | 17 V - Limits downstream circuit voltage during 21.7 A surge, protecting 24 V tolerant ICs |
| IPP (8/20 µs) | 21.7 A - Withstands high-energy transients such as load dump-induced spikes |
| Leakage (IR) | 1 µA at 85 °C - Minimizes standby power loss in always-on vehicle modules |
| PPP | 400 W (10/1000 µs) - Sustains repetitive surges without thermal runaway in engine control units |
| Tj max | +150 °C - Enables placement near heat sources like power converters or ECUs |
| ESD rating | ±30 kV contact/air (ISO 10605) - Meets OEM requirements for human-body-model robustness |
Pinout & Package
SM4T12CAY is housed in an SMA (DO-214AC) surface-mount package per JEDEC outline, with two terminals: Cathode (K) and Anode (A). The bidirectional design means both terminals function symmetrically as clamping nodes-no polarity assignment required in layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Transient return path (bidirectional) | Connects to protected line; conducts during positive or negative overvoltage events |
| Cathode (K) | Transient return path (bidirectional) | Connects to ground or reference rail; completes low-impedance surge shunt path |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use including temperature cycling, humidity, and mechanical shock |
| Low dynamic resistance (RD) | 0.089 Ω - Reduces clamping voltage rise under high-current pulses, improving protection margin |
| UL94 V0 resin encapsulation | Meets flammability safety standard for engine compartment and cabin electronics |
| Planar junction technology | Enables stable leakage performance and long-term reliability at elevated junction temperatures |
| ISO 7637-2 compliance | Rated for Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), Pulse 3b (+150 V) |
Applications
| Body Control Module (BCM) | Infotainment Power Input |
|---|---|
|
Use Scenario: Protects LIN/CAN bus power rails and microcontroller supply inputs against battery line transients during ignition and alternator load dump. IC Role / Device Role / Timing Role: Bidirectional TVS clamp placed directly at connector entry point before DC-DC converter input. Use Value: Clamps 17 V at 21.7 A, preventing latch-up or damage to 24 V-rated PMICs and MCU LDOs during ISO 7637-2 Pulse 2a (+112 V) events. |
Use Scenario: Shields USB-C and HDMI power delivery lines in head unit front-end from ESD and hot-swap surges. IC Role / Device Role / Timing Role: Primary ESD suppressor on 5 V/12 V auxiliary power inputs, positioned before fuse and filter capacitor. Use Value: Delivers ±30 kV air/contact ESD immunity per ISO 10605 while maintaining <1 µA leakage at 85 °C for low-power standby modes. |
| Electric Power Steering (EPS) | ADAS Camera Module |
|
Use Scenario: Guards motor driver gate drive supply and position sensor interface against coupled transients from high-current H-bridge switching. IC Role / Device Role / Timing Role: Secondary protection stage after bulk capacitance, placed adjacent to isolated gate driver IC supply pins. Use Value: Withstands 400 W peak pulse power at Tj = 150 °C, ensuring uninterrupted operation during repeated steering actuation surges. |
Use Scenario: Secures MIPI CSI-2 power and I²C control lines in rear-view camera modules exposed to cable discharge events. IC Role / Device Role / Timing Role: Low-capacitance TVS (CJ ≈ 1000 pF at 0 V) placed inline with signal traces to avoid signal integrity degradation. Use Value: Bidirectional clamping prevents reverse-bias damage to image sensor I/O cells during hot-plug or static discharge on coaxial video cables. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ12CA | Higher VCL (20.1 V vs. 17 V), lower IPP (19.9 A), same SMA package | Limited margin for 24 V-tolerant receivers; less effective for tight-clamp designs | Prefer SM4T12CAY where clamping voltage headroom is constrained below 18 V |
| TPSMA6L12A | Unidirectional only; requires dual-device implementation for bidirectional protection | Increases BOM count and PCB area; introduces asymmetry in surge response | Choose SM4T12CAY when single-device bidirectional clamping simplifies layout and improves symmetry |
Compared with SMAJ12CA and TPSMA6L12A, SM4T12CAY delivers tighter clamping (17 V), higher surge current handling (21.7 A), and native bidirectionality-making it optimal for space-constrained, high-reliability 12 V automotive power rails where voltage margin and layout simplicity are critical.
Availability
SM4T12CAY is available at Aetrix Electronics and suitable for body control modules, ADAS camera power inputs, and electric power steering systems requiring stable component supply with full AEC-Q101 traceability and automotive-grade lifecycle support.
Supply support for SM4T12CAY 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, specializing in automotive, industrial, and power management solutions with vertical manufacturing capabilities and broad automotive qualification coverage.
The SM4Txx series belongs to ST's automotive-grade transient protection product line, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V and 24 V vehicle electrical architectures.
FAQ
What is the difference between SM4T12AY and SM4T12CAY?
SM4T12AY is unidirectional (anode-to-cathode conduction only), while SM4T12CAY is bidirectional-capable of clamping overvoltage in both polarities. This makes SM4T12CAY suitable for AC-coupled or polarity-agnostic lines like CAN bus power or differential sensor supplies without external diode pairing.
Can SM4T12CAY be used in 24 V systems?
No-SM4T12CAY is rated for 12 V nominal battery systems. Its 12.3 V VBR max and 17 V VCL are optimized for clamping transients superimposed on 12 V rails. For 24 V systems, ST recommends SM4T24CAY (VBR = 22.2–24.6 V) to maintain adequate standoff margin above normal operating voltage.
Does SM4T12CAY require a heatsink?
No external heatsink is required. Its SMA package achieves Rth(j-a) ≈ 120 °C/W on a standard FR4 board with 1 cm² copper per lead, and its 400 W peak pulse rating is specified for single-pulse conditions with Tj initial = 25 °C-sufficient for ISO 7637-2 transient durations (ms-scale).
Is SM4T12CAY RoHS and REACH compliant?
Yes-SM4T12CAY is manufactured in ST's ECOPACK2-compliant facilities and meets RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, including SVHC screening. Full material declarations and CoC are available via ST's quality portal upon request.
SM4T12CAY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SM4TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 10V
- Voltage - Breakdown (Min):
- 11.1V
- Voltage - Clamping (Max) @ Ipp:
- 21.7V
- Current - Peak Pulse (10/1000µs):
- 106A (8/20µs)
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SM4T12CAY FAQ
1.How can I place an order for SM4T12CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T12CAY 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 SM4T12CAY reliable?
The price and inventory of SM4T12CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T12CAY is usually 5 days.
3.What payment methods are accepted for SM4T12CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T12CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T12CAY?
SM4T12CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T12CAY 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 SM4T12CAY?
For technical support, including SM4T12CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T12CAY requirements.
6.How does Aetrix verify that SM4T12CAY is sourced from the original manufacturer or authorized distributors?
All SM4T12CAY 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 SM4T12CAY meets industry standards.
7.What is the process for return or replacement of SM4T12CAY?
All SM4T12CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T12CAY, 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 SM4T12CAY part is unused and in its original packaging.
Return procedure for SM4T12CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T12CAY Tags
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