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STMicroelectronics SM4T15CAY
- Part No.:
- SM4T15CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T15CAY.pdf
- Description:
- TVS DIODE 13VWM 27.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:6,933
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Product details
Overview
SM4T15CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 pulse protection in 12 V vehicle systems. It features a standoff voltage (VRM) of 13 V, clamping voltage (VCL) of 21.5 V at 18.6 A (10/1000 µs), peak pulse power of 400 W, and operates up to 150 °C junction temperature - deployed in engine control units, body control modules, and infotainment power rails.
For engineers reviewing the SM4T15CAY datasheet, SM4T15CAY pinout, SM4T15CAY application, or SM4T15CAY equivalent, key selection criteria include bidirectional surge capability per ISO 10605 (±30 kV ESD), low leakage (≤1 µA at 85 °C), JEDEC-standard SMA package compatibility, and verified compliance with ISO 7637-2 Pulse 1/2a/3a/3b waveforms in automotive 12 V networks.
Technical Context
The SM4T15CAY uses planar silicon technology to achieve stable breakdown behavior across temperature (αT = 8.4 × 10⁻⁴ /°C), low dynamic resistance (RD = 0.132 Ω), and minimal capacitance (<100 pF at 1 V). Its bidirectional architecture enables symmetric clamping for both positive and negative transients without polarity dependency.
It is rated for 400 W peak pulse power under 10/1000 µs waveform and 2.3 kW under 8/20 µs, with clamping voltage tightly bounded between 21.5 V (10/1000 µs) and 27.2 V (8/20 µs) at rated current - ensuring predictable overvoltage limiting during load dump or inductive switching events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 13 V - Maximum continuous reverse operating voltage before significant leakage; sets minimum system rail margin for 12 V automotive use. |
| Breakdown Voltage (VBR) | 14.4–16.0 V at 1 mA - Confirmed voltage range where avalanche conduction initiates; ensures reliable triggering above nominal battery voltage. |
| Clamping Voltage (VCL) | 21.5 V at 18.6 A (10/1000 µs) - Peak voltage seen by protected circuit during standardized surge; guarantees downstream ICs remain below 24 V absolute max. |
| Peak Pulse Power | 400 W (10/1000 µs) - Sustained energy-handling capacity matching ISO 7637-2 Pulse 1 & 3b severity levels in 12 V systems. |
| Leakage Current (IRM) | ≤1 µA at 85 °C - Ultra-low off-state current preserves battery drain budgets in always-on automotive modules. |
| Junction Temperature Range | −55 °C to +150 °C - Validated operation across full automotive ambient envelope including under-hood environments. |
| ESD Rating | ±30 kV contact/air discharge (ISO 10605, C = 150/330 pF) - Meets OEM-level electrostatic immunity requirements for exposed connectors and sensors. |
Pinout & Package
SM4T15CAY is housed in an industry-standard SMA (DO-214AC) surface-mount package per JEDEC outline, with two terminals: Cathode and Anode arranged in a symmetrical bidirectional configuration. The package measures 4.80–5.35 mm (E) × 2.25–2.90 mm (D) × 0.75–1.50 mm (L), optimized for FR4 PCBs with 70 µm copper and recommended 5.43 mm × 1.40 mm footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry point (negative surge) | Accepts reverse-polarity surges (e.g., ISO 7637-2 Pulse 1, −150 V); forms one half of symmetrical clamping path. |
| Cathode | Transient current entry point (positive surge) | Accepts forward-polarity surges (e.g., ISO 7637-2 Pulse 2a, +112 V); completes bidirectional conduction loop with Anode. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive electronics per stress test requirements - enables direct use in safety-critical ECUs without additional qualification. |
| Bidirectional clamping | Single-device protection against both polarities of transients - eliminates need for dual-diode arrangements or polarity-aware layout. |
| Low dynamic resistance (RD) | 0.132 Ω - Minimizes clamping voltage rise under high-current pulses, improving protection margin for 3.3 V/5 V logic interfaces. |
| UL94 V0-compliant resin | Flame-retardant encapsulation meeting automotive cabin and under-hood flammability standards. |
| Planar junction construction | Enables stable leakage performance (≤1 µA @ 85 °C) and predictable VBR temperature coefficient (8.4 × 10⁻⁴ /°C) over life. |
Applications
| Engine Control Unit (ECU) Power Input | Automotive Infotainment USB Port |
|---|---|
|
Use Scenario: Protection of 12 V supply rail against load dump (ISO 7637-2 Pulse 3b, +150 V) and alternator ripple-induced spikes. IC Role / Device Role / Timing Role: Primary bidirectional TVS clamp placed upstream of DC-DC converter input stage. Use Value: Limits transient voltage to ≤21.5 V at 18.6 A, preventing overvoltage failure of buck controller ICs and enabling single-stage protection without series impedance. |
Use Scenario: ESD and surge protection on USB VBUS line exposed to hot-plug events and dashboard static discharge. IC Role / Device Role / Timing Role: Secondary protection device after common-mode choke, shunting fast transients before USB PHY interface. Use Value: Withstands ±30 kV contact ESD (ISO 10605) and clamps 8/20 µs surges to ≤27.2 V, preserving signal integrity and preventing PHY latch-up. |
| Body Control Module (BCM) LIN Bus Line | ADAS Camera Power Interface |
|
Use Scenario: Transient suppression on LIN bus power line subjected to battery disconnection events (ISO 7637-2 Pulse 1, −150 V). IC Role / Device Role / Timing Role: Low-leakage (≤1 µA @ 85 °C) TVS placed directly at connector entry point. Use Value: Prevents false LIN resets during cold-cranking while maintaining <1 µA standby current - critical for low-power sleep mode compliance. |
Use Scenario: Protection of 12 V camera module input against ignition noise and cable-bend-induced surges in rear-view systems. IC Role / Device Role / Timing Role: First-line defense mounted adjacent to Fakra connector, before EMI filter and LDO. Use Value: 150 °C junction rating allows placement near heat-generating image sensor; 400 W pulse rating handles repeated micro-surge events without degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ15CA | Same VRM (13 V) and VBR range, but lower PPP (400 W same), higher RD (0.22 Ω), no AEC-Q101 qualification. | Approved for industrial/commercial use only; not validated for automotive thermal cycling or humidity testing. | Select when cost sensitivity outweighs automotive qualification requirements and board space permits larger SMAJ footprint. |
| TPSMD15C | Identical VRM/VBR specs and AEC-Q101 grade, but higher VCL (23.2 V @ 18.6 A) and lower PPP (300 W). | Limited to lower-energy surge environments (e.g., non-engine-bay modules); insufficient for full ISO 7637-2 Pulse 3b compliance. | Choose where system-level testing confirms 23.2 V clamping is acceptable and 300 W pulse handling meets worst-case transient energy. |
Compared with SMAJ15CA and TPSMD15C, SM4T15CAY delivers superior automotive robustness via AEC-Q101 validation, tighter clamping (21.5 V vs. ≥23.2 V), and guaranteed 400 W pulse capability - making it the preferred choice for engine bay, BCM, and ADAS power rail protection where reliability is non-negotiable.
Availability
SM4T15CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, and ADAS camera power interfaces requiring stable component supply across extended automotive product lifecycles.
Supply support for SM4T15CAY 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 and broad IP portfolio.
The SM4Txx series belongs to ST's automotive-qualified TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle architectures - emphasizing long-term reliability under thermal stress and mechanical vibration.
FAQ
Is SM4T15CAY unidirectional or bidirectional?
SM4T15CAY is a bidirectional TVS diode, as indicated by the "C" in its part number suffix. It provides symmetrical clamping for both positive and negative transients, enabling single-device protection on floating or AC-coupled lines such as LIN bus power or differential signal pairs without polarity concerns.
What is the maximum clamping voltage under 8/20 µs surge conditions?
Under 8/20 µs surge conditions, SM4T15CAY clamps to 27.2 V at 85 A peak current, as specified in Table 2 of DS6927 Rev 6. This value reflects worst-case conduction under fast-rising transients like EFT bursts or nearby lightning-induced coupling, ensuring downstream components remain within safe operating voltage limits.
Does SM4T15CAY require external series impedance for optimal protection?
No external series impedance is required for basic overvoltage clamping, as SM4T15CAY's low dynamic resistance (0.132 Ω) enables effective voltage limiting without added components. However, a small ferrite bead or resistor may be added upstream to limit di/dt and reduce ringing in high-frequency ESD events - per AN2689 design guidelines.
Can SM4T15CAY be used in 24 V truck systems?
SM4T15CAY is rated for 12 V automotive systems only, with VRM = 13 V and ISO 7637-2 compliance defined for 12 V battery architecture. For 24 V trucks, ST recommends SM4T28CAY (VRM = 24 V) or SM4T33CAY (VRM = 28 V), which match higher battery voltage thresholds and pulse amplitude requirements per ISO 7637-2 Annex D.
SM4T15CAY 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):
- 13V
- Voltage - Breakdown (Min):
- 14.4V
- Voltage - Clamping (Max) @ Ipp:
- 27.2V
- Current - Peak Pulse (10/1000µs):
- 85A (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)
SM4T15CAY FAQ
1.How can I place an order for SM4T15CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T15CAY 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 SM4T15CAY reliable?
The price and inventory of SM4T15CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T15CAY is usually 5 days.
3.What payment methods are accepted for SM4T15CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T15CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T15CAY?
SM4T15CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T15CAY 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 SM4T15CAY?
For technical support, including SM4T15CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T15CAY requirements.
6.How does Aetrix verify that SM4T15CAY is sourced from the original manufacturer or authorized distributors?
All SM4T15CAY 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 SM4T15CAY meets industry standards.
7.What is the process for return or replacement of SM4T15CAY?
All SM4T15CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T15CAY, 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 SM4T15CAY part is unused and in its original packaging.
Return procedure for SM4T15CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T15CAY Tags
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