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STMicroelectronics SM4T14AY
- Part No.:
- SM4T14AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T14AY.pdf
- Description:
- TVS DIODE 12VWM 25.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,913
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Product details
Overview
SM4T14AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 19.9 V (VCL) at 20.1 A (IPP, 10/1000 µs), with 400 W peak pulse power and 0.2 µA leakage at 25 °C. It protects CAN, LIN, and sensor interfaces in 12 V automotive systems against ISO 7637-2 pulses (Pulse 1: −150 V; Pulse 2a: +112 V) and ISO 10605 ESD (±30 kV).
For engineers reviewing the SM4T14AY datasheet, SM4T14AY pinout, SM4T14AY application, or SM4T14AY equivalent, this device is selected for robust front-end surge protection in engine control units, body control modules, and ADAS camera power rails where low leakage, high Tj (150 °C), and JEDEC-compliant SMA footprint are critical.
Technical Context
The SM4T14AY uses planar silicon technology to achieve stable breakdown voltage (VBR = 13.3–14.7 V at IBR = 1 mA) and low dynamic resistance (RD = 0.259 Ω), enabling precise clamping during fast transients. Its unidirectional polarity supports DC-biased signal lines like power supply inputs and sensor VCC rails.
It meets ISO 7637-2 immunity requirements for automotive electronics: Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V), with junction temperature operation from −55 °C to +150 °C and storage range up to +150 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 13.3 V / 14.0 V / 14.7 V at 1 mA - defines reliable turn-on threshold before clamping begins |
| VCL @ 20.1 A | 19.9 V (10/1000 µs) - maximum voltage seen by protected circuit during rated surge |
| IPP (10/1000 µs) | 20.1 A - peak current capability matching ISO 7637-2 Pulse 1 energy level |
| RD | 0.259 Ω - low dynamic resistance ensures minimal voltage overshoot during fast transients |
| IR @ VRM | 0.2 µA at 25 °C - ultra-low leakage preserves battery life in always-on automotive modules |
| Tj max | +150 °C - enables placement near heat sources (e.g., ECUs, power converters) without derating |
| Package | SMA (DO-214AC) - JEDEC-registered surface-mount outline with 5.35 mm × 4.60 mm footprint |
Pinout & Package
SMA (DO-214AC) package: molded epoxy case with cathode band marking; compliant with IPC 7531 footprint; lead-free, RoHS-compliant, UL94 V0 resin.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Ground reference terminal | Connected to system ground or low-side return path; completes conduction path during reverse surge |
| Cathode | Protected line input | Connected to line under protection (e.g., 12 V rail); blocks normal operation, conducts during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use including thermal cycling, humidity, and mechanical shock |
| Low leakage (0.2 µA @ 25 °C) | Minimizes standby current drain in always-on vehicle networks (e.g., CAN wake-up circuits) |
| High Tj rating (150 °C) | Enables direct placement on hot PCB areas without thermal derating or heatsinking |
| ISO 7637-2 compliance | Guarantees protection against load dump, inductive switching, and alternator transients in 12 V systems |
| JEDEC-standard SMA footprint | Ensures compatibility with standard SMT assembly lines and reflow profiles (J-STD-020) |
Applications
| Engine Control Unit (ECU) Power Input | ADAS Camera Module Supply Rail |
|---|---|
|
Use Scenario: Protects 12 V input of diesel/gasoline ECU against load dump (ISO 7637-2 Pulse 2a) and alternator-induced spikes. IC Role / Device Role / Timing Role: Unidirectional TVS clamps positive transients while blocking reverse leakage during normal operation. Use Value: Limits voltage to ≤19.9 V during 20.1 A surge, preventing damage to downstream LDOs and microcontrollers. |
Use Scenario: Shields 12 V power feed to forward-facing camera module from ignition noise and ESD events during vehicle start-stop cycles. IC Role / Device Role / Timing Role: Fast-response transient suppressor placed upstream of DC-DC converter input. Use Value: Withstands ±30 kV contact discharge (ISO 10605) and clamps ISO 7637-2 Pulse 3b (+150 V) within 1 ns response time. |
| Body Control Module (BCM) LIN Bus | Electric Power Steering (EPS) Sensor Interface |
|
Use Scenario: Guards LIN transceiver VCC pin against battery reversal and jump-start transients in door modules and lighting controllers. IC Role / Device Role / Timing Role: Standoff voltage (VRM = 12 V) matches LIN bus operating range; clamps only above safe margin. Use Value: 0.2 µA leakage avoids false wake-up in sleep mode; 150 °C Tj rating accommodates under-dash mounting. |
Use Scenario: Protects torque and position sensor analog supply lines in EPS systems exposed to motor commutation noise and load dump. IC Role / Device Role / Timing Role: Low RD (0.259 Ω) minimizes clamping voltage overshoot during fast 8/20 µs transients. Use Value: Delivers 25.3 A surge current handling (8/20 µs) while maintaining VCL ≤ 25.3 V - preserving ADC reference integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ14A | VBR = 15.6–17.2 V; VCL = 23.2 V @ 17.3 A; RD = 0.33 Ω; same SMA package | Higher clamping voltage reduces protection margin for 12 V systems with tight voltage tolerances | Prefer SM4T14AY when VCL ≤ 20 V is required to protect 16 V-rated downstream ICs |
| 1.5SMC14A | VBR = 14.9–16.5 V; VCL = 23.2 V @ 64.7 A; 1500 W rating; larger SMC package | Higher power rating but incompatible footprint; requires PCB redesign and higher layout inductance | Select only if system-level surge energy exceeds 400 W and board space allows SMC (7.11 mm × 6.22 mm) |
Compared with SMAJ14A and 1.5SMC14A, SM4T14AY offers tighter VBR tolerance (±5%), lower VCL, and AEC-Q101 validation - making it optimal for space-constrained, safety-critical 12 V automotive nodes where clamping precision and reliability outweigh raw power rating.
Availability
SM4T14AY is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, and body control modules requiring stable component supply across automotive production lifecycles.
Supply support for SM4T14AY 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 automotive-grade analog, power, and microcontroller solutions since 1987.
The SM4TxxAY series belongs to ST's automotive transient voltage suppression portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle electrical architectures.
FAQ
Is SM4T14AY bidirectional or unidirectional?
SM4T14AY is unidirectional. Its cathode is marked with a band and must be connected to the line under protection, while the anode connects to ground. This configuration blocks reverse current during normal operation and conducts only during positive overvoltage events - ideal for DC power rails and biased signal lines.
What is the maximum clamping voltage at 8/20 µs surge?
At 8/20 µs waveform, SM4T14AY clamps to 25.3 V with 25.3 A peak current (VCL = 25.3 V). This value is derived from VBRmax (14.7 V) plus RD × IPP (0.259 Ω × 25.3 A), ensuring predictable voltage limiting during fast transients like ESD or inductive switching.
Can SM4T14AY replace SM4T14CAY in a design?
No - SM4T14AY is unidirectional; SM4T14CAY is bidirectional. Substituting them requires circuit review: unidirectional devices require correct polarity installation and cannot suppress negative transients on AC-coupled or floating lines, whereas bidirectional types protect both polarities without orientation dependency.
Does SM4T14AY require derating at elevated ambient temperatures?
Yes - its peak pulse power decreases with rising junction temperature. At Tj = 125 °C, PPP drops to ~270 W (per Figure 3 in DS6927), so designs operating near 150 °C ambient must verify thermal layout (copper area, airflow) to maintain Tj ≤ 125 °C during surge events.
SM4T14AY 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:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 12V
- Voltage - Breakdown (Min):
- 13.3V
- Voltage - Clamping (Max) @ Ipp:
- 25.3V
- Current - Peak Pulse (10/1000µs):
- 91A (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)
SM4T14AY FAQ
1.How can I place an order for SM4T14AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T14AY 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 SM4T14AY reliable?
The price and inventory of SM4T14AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T14AY is usually 5 days.
3.What payment methods are accepted for SM4T14AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T14AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T14AY?
SM4T14AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T14AY 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 SM4T14AY?
For technical support, including SM4T14AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T14AY requirements.
6.How does Aetrix verify that SM4T14AY is sourced from the original manufacturer or authorized distributors?
All SM4T14AY 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 SM4T14AY meets industry standards.
7.What is the process for return or replacement of SM4T14AY?
All SM4T14AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T14AY, 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 SM4T14AY part is unused and in its original packaging.
Return procedure for SM4T14AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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