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STMicroelectronics SMA6T18CAY
- Part No.:
- SMA6T18CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMA6T18CAY.pdf
- Description:
- TVS DIODE 15.3VWM 32.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,940
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Product details
Overview
SMA6T18CAY from STMicroelectronics is a bidirectional 600 W automotive-grade transient voltage suppressor (TVS) diode in SMA package, designed for ISO 7637-2 pulse protection and ISO 10605 ESD immunity in 12 V/24 V vehicle systems. It features 18 V breakdown voltage (VBR = 17.1–18.9 V), 25.2 V clamping voltage at 24 A (10/1000 µs), and ≤0.2 µA leakage at 25 °C - enabling robust surge suppression in engine control units, body electronics, and infotainment power rails.
For engineers reviewing the SMA6T18CAY datasheet, SMA6T18CAY pinout, SMA6T18CAY application, or SMA6T18CAY equivalent, key selection criteria include unidirectional vs. bidirectional polarity, clamping voltage under 24 A surge, junction temperature derating up to 150 °C, and compliance with ISO 7637-2 Pulse 1/2a/3a/3b and IEC 61000-4-2 Level 4 ESD.
Technical Context
This TVS operates as a voltage-clamped shunt protector: during transients exceeding its reverse standoff voltage (VRWM = 15.3 V), it avalanches to clamp energy into ground while maintaining low dynamic resistance (RD = 0.263 Ω at 24 A). Its planar silicon junction enables stable leakage performance across -55 °C to +150 °C operating range.
The device meets AEC-Q101 qualification and supports dual-standard surge immunity: 30 kV contact/air discharge per ISO 10605 (C = 150/330 pF), and ISO 7637-2 pulses including -150 V (Pulse 1), +112 V (Pulse 2a), -220 V (Pulse 3a), and +150 V (Pulse 3b) - all validated on automotive 12 V battery systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Breakdown Voltage (VBR) | 17.1–18.9 V at 1 mA - defines precise avalanche onset for predictable clamping behavior |
| Clamping Voltage (VCL) | 25.2 V at 24 A (10/1000 µs) - limits peak voltage seen by protected ICs during surge events |
| Peak Pulse Power | 600 W (10/1000 µs) - sustains high-energy transients without failure in automotive environments |
| Leakage Current (IR) | ≤0.2 µA at 15.3 V, 25 °C - ensures minimal standby power loss in always-on vehicle modules |
| Operating Junction Temp. | -55 to +150 °C - supports under-hood placement and long-term reliability in thermal cycling |
| ESD Withstand | 30 kV air/contact discharge (ISO 10605, C = 150/330 pF) - exceeds Level 4 for touch-sensitive interfaces |
| Package | SMA (DO-214AC) - JEDEC-registered surface-mount outline compatible with standard FR4 PCB footprints |
Pinout & Package
SMA6T18CAY uses the standard SMA (DO-214AC) package: a two-terminal surface-mount device with cathode band marking. The package measures 4.80–5.35 mm (E) × 2.25–2.90 mm (D) × 1.90–2.45 mm (A1) and features matte tin-plated leads compliant with J-STD-002 and RoHS.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection to protected line | Receives transient current during positive surges (bidirectional operation) |
| Cathode | High-side connection to ground reference | Provides return path for clamped current; marked by band on package body |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive use per stress test requirements including temperature cycling, HTRB, and ESD |
| Bidirectional surge handling | Clamps both positive and negative transients - eliminates need for dual-device configurations |
| Low dynamic resistance | RD = 0.263 Ω at 24 A - minimizes voltage overshoot during fast-rising pulses (e.g., ISO 7637-2 Pulse 3b) |
| High-temperature stability | Leakage remains ≤1 µA at 85 °C - critical for engine bay and powertrain applications |
| J-STD-020 MSL Level 1 | Unlimited floor life at ≤30 °C/60% RH - simplifies SMT assembly without baking requirements |
Applications
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|---|---|
Use Scenario: Protection of LIN bus transceivers and sensor inputs against load dump and alternator ripple. IC Role / Device Role / Timing Role: Shunt clamping element placed between power rail and ground, responding within nanoseconds to overvoltage events. Use Value: Prevents latch-up or permanent damage to microcontrollers and analog front-ends during ISO 7637-2 Pulse 1 (-150 V) and Pulse 2a (+112 V). |
Use Scenario: Safeguarding door module power inputs exposed to ESD from human contact and relay switching noise. IC Role / Device Role / Timing Role: Fast-response voltage clamp on 12 V supply lines feeding window lift motors and mirror actuators. Use Value: Maintains system uptime by absorbing 30 kV contact discharge (ISO 10605) without degradation or leakage increase. |
| Infotainment Head Unit | ADAS Camera Power Input |
Use Scenario: Surge protection on USB-C and HDMI power delivery lines subjected to hot-plug transients and ESD. IC Role / Device Role / Timing Role: Bidirectional clamping device placed upstream of DC-DC converters supplying SoC and display drivers. Use Value: Limits clamped voltage to 25.2 V during 24 A surges, preserving input stage integrity of buck regulators rated for 28 V max. |
Use Scenario: Protecting 5 V/3.3 V camera module power rails from ignition-induced transients in rear-view or surround-view systems. IC Role / Device Role / Timing Role: Low-leakage TVS integrated into compact camera flex PCB near connector entry point. Use Value: Enables reliable operation at 150 °C junction temperature while maintaining <0.2 µA leakage - reducing dark current in CMOS image sensors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMA6T18AY | Unidirectional configuration; same VBR, VCL, and PPP | Requires external polarity-aware layout; unsuitable for AC-coupled or floating signal lines | Select when protecting only positive-going transients on grounded-return systems |
| SMBJ18CA | Higher 600 W rating but SMB package (larger footprint); VCL = 29.2 V @ 20.9 A | Lower power density; less suitable for space-constrained modules like ADAS cameras | Choose when board area allows larger package and higher clamping voltage is acceptable |
Compared with SMA6T18AY, SMA6T18CAY adds bidirectional capability without sacrificing leakage or thermal performance; versus SMBJ18CA, it delivers identical surge rating in 30% smaller footprint and 3.9 V lower clamping voltage - directly improving downstream IC survivability.
Availability
SMA6T18CAY is available at Aetrix Electronics and suitable for engine control units, body electronics modules, infotainment head units, and ADAS camera power supplies requiring stable component supply across automotive production lifecycles.
Supply support for SMA6T18CAY 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 AEC-Q100/Q101 qualification expertise.
SMA6T18CAY belongs to the SMA6TY Transil series - engineered specifically for automotive-grade transient suppression in 12 V/24 V systems, emphasizing low leakage, high-temperature stability, and multi-standard compliance (ISO 7637-2, ISO 10605, IEC 61000-4-2).
FAQ
What is the maximum clamping voltage of SMA6T18CAY under a 24 A surge?
The maximum clamping voltage is 25.2 V at 24 A for a 10/1000 µs waveform, measured at Tj = 25 °C. This value increases with junction temperature using the coefficient αT = 8.8 × 10−4/°C, reaching ~27.1 V at 125 °C per the VCL vs. Tj formula in DS6931 Rev 9.
Can SMA6T18CAY replace SMA6T18AY in an existing design?
No - SMA6T18CAY is bidirectional while SMA6T18AY is unidirectional. Substitution requires verifying that the protected circuit can tolerate reverse conduction during negative transients. Layout changes may be needed to avoid unintended current paths in grounded-return systems.
Does SMA6T18CAY meet UL 94 V0 flammability requirements?
Yes - the SMA6T18CAY package complies with UL 94 V0, confirmed in the DS6931 Rev 9 datasheet Section "Complies with the following standards". This ensures flame-retardant epoxy molding compound suitable for enclosed automotive enclosures.
What is the recommended PCB footprint for SMA6T18CAY?
The manufacturer specifies a footprint with 5.43 mm pad length (2.63 mm center-to-center spacing), 1.40 mm pad width, and 1.64 mm solder mask opening - matching JEDEC DO-214AC and IPC7531 guidelines. Thermal relief via copper area under each lead improves power dissipation and solder joint reliability.
SMA6T18CAY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SMA6TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 15.3V
- Voltage - Breakdown (Min):
- 17.1V
- Voltage - Clamping (Max) @ Ipp:
- 32.3V
- Current - Peak Pulse (10/1000µs):
- 123A (8/20µs)
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMA6T18CAY FAQ
1.How can I place an order for SMA6T18CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SMA6T18CAY 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 SMA6T18CAY reliable?
The price and inventory of SMA6T18CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA6T18CAY is usually 5 days.
3.What payment methods are accepted for SMA6T18CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA6T18CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMA6T18CAY?
SMA6T18CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMA6T18CAY 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 SMA6T18CAY?
For technical support, including SMA6T18CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA6T18CAY requirements.
6.How does Aetrix verify that SMA6T18CAY is sourced from the original manufacturer or authorized distributors?
All SMA6T18CAY 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 SMA6T18CAY meets industry standards.
7.What is the process for return or replacement of SMA6T18CAY?
All SMA6T18CAY units undergo pre-shipment inspection (PSI). If there is an issue with SMA6T18CAY, 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 SMA6T18CAY part is unused and in its original packaging.
Return procedure for SMA6T18CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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