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STMicroelectronics SM6T18CAY
- Part No.:
- SM6T18CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SM6T18CAY.pdf
- Description:
- TVS DIODE 15.3VWM 25.2VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:13,663
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Product details
Overview
SM6T18CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMB package, designed for ISO 7637-2 pulse protection and IEC 61000-4-2 ESD immunity in 12 V vehicle systems. It features a 18 V standoff voltage (VRM), 25.2 V clamping voltage (VCL) at 1 A IPP, 600 W peak pulse power (10/1000 µs), and AEC-Q101 qualification for under-hood reliability.
For engineers reviewing the SM6T18CAY datasheet, SM6T18CAY pinout, SM6T18CAY application, or SM6T18CAY equivalent, this device is selected for high-reliability automotive power line surge protection where low leakage (≤1 µA at 85 °C), stable clamping under junction temperature up to 150 °C, and bidirectional polarity handling are required.
Technical Context
This bidirectional TVS diode operates symmetrically across both polarities, enabling robust protection of differential or floating automotive signal/power lines without polarity dependency. Its planar silicon structure delivers low dynamic resistance (RD = 0.263 Ω) and stable breakdown voltage drift coefficient (αT = 8.8 × 10⁻⁴ /°C), ensuring predictable clamping performance over temperature.
It meets stringent automotive transients: ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V), while sustaining 30 kV ESD per ISO 10605 (C = 330 pF, R = 330 Ω) - all verified at Tj = 150 °C with no derating loss in peak power capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - Maximum continuous reverse operating voltage before significant conduction begins; defines minimum system operating margin. |
| Clamping Voltage (VCL) | 25.2 V at 1 A IPP (10/1000 µs) - Peak voltage seen by protected circuit during surge; ensures downstream ICs rated ≥28 V remain within safe operating area. |
| Peak Pulse Power | 600 W (10/1000 µs) - Sustains automotive load dump surges without failure; derates to 515 W at Tj = 150 °C per Figure 3. |
| Leakage Current | ≤1 µA at 85 °C - Enables low-power always-on circuits (e.g., CAN wake-up receivers) without battery drain impact. |
| Dynamic Resistance (RD) | 0.263 Ω - Low impedance limits voltage overshoot during fast transients; critical for protecting sensitive analog front-ends. |
| AEC-Q101 Qualified | Qualified for automotive under-hood use - guarantees reliability across −55 °C to +150 °C junction temperature range with zero early-life failures. |
| ESD Rating | ±30 kV contact & air discharge (ISO 10605, C = 330 pF/R = 330 Ω) - Exceeds Level 4 requirement; eliminates need for secondary ESD stages. |
Pinout & Package
The SM6T18CAY is housed in an SMB (DO-214AA) surface-mount package with two terminals: Cathode (K) and Anode (A). The bidirectional configuration means both terminals function identically - no polarity marking required for installation. Package dimensions conform to JEDEC MO-136AB: D = 3.3–3.95 mm, E = 5.1–5.6 mm, L = 0.75–1.5 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Transient current entry point (positive polarity) | Conducts surge current when voltage exceeds +VBR; forms symmetrical path with cathode for bidirectional clamping. |
| Cathode (K) | Transient current entry point (negative polarity) | Conducts surge current when voltage exceeds −VBR; enables full-cycle protection without external polarity management. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping symmetry | Identical VBR (15.3–18.9 V) and VCL (25.2 V) for both polarities - simplifies PCB layout and eliminates polarity-sensitive routing. |
| High-temperature surge capability | Maintains 515 W (10/1000 µs) peak power at Tj = 150 °C - supports engine control units and ADAS modules near heat sources. |
| Low dynamic resistance | RD = 0.263 Ω - minimizes voltage overshoot during sub-microsecond transients (e.g., ISO 7637-2 Pulse 3b). |
| AEC-Q101 qualification | Validated for automotive Grade 1 (−40 °C to +125 °C ambient) and extended operation to +150 °C junction - meets OEM long-term reliability requirements. |
| Matte tin lead finish | Complies with J-STD-002, JESD 22-B102 E3, and IPC7531 footprint - ensures solder joint integrity and whisker resistance in automated assembly. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Line |
|---|---|
|
Use Scenario: Protects 12 V supply rail of engine ECU against load dump, jump-start spikes, and alternator ripple. IC Role / Device Role / Timing Role: Primary surge clamp on main power input, placed upstream of DC-DC converters and microcontroller LDOs. Use Value: Clamps transients to ≤25.2 V, preventing latch-up or damage to 28 V-rated power management ICs while maintaining AEC-Q101 compliance. |
Use Scenario: Shields LIN physical layer transceivers from ESD events and battery disconnect transients in door modules and seat controllers. IC Role / Device Role / Timing Role: Bidirectional line protector on LIN bus (12 V nominal), co-located with transceiver IC. Use Value: Withstands ±30 kV ESD and ISO 7637-2 Pulse 3a/b without degradation, eliminating need for series resistors or RC filters that impair signal rise time. |
| Advanced Driver Assistance Systems (ADAS) Camera Power | Infotainment Head Unit USB Interface |
|
Use Scenario: Safeguards 12 V camera module power input in rear-view and surround-view systems exposed to harsh thermal cycling and vibration. IC Role / Device Role / Timing Role: First-line transient suppressor before buck converter and image sensor power domain. Use Value: Operates reliably at Tj = 150 °C under hood, with <1 µA leakage preserving low-power sleep mode current budget. |
Use Scenario: Protects USB VBUS line in head unit against hot-plug surges and ESD during user insertion of mobile devices. IC Role / Device Role / Timing Role: Secondary-level TVS on 5 V USB rail, placed after primary 12 V input protection. Use Value: Low RD (0.263 Ω) ensures minimal VBUS droop during 1 A surge, maintaining USB enumeration stability and data link integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CA | Same SMB package, but lower peak power (400 W @ 10/1000 µs) and higher VCL (29.2 V at 1 A); not AEC-Q101 qualified. | Limited to non-automotive industrial or consumer power rails; unsuitable for ISO 7637-2 Pulse 1/2a compliance. | Select only if cost sensitivity outweighs automotive qualification and clamping performance. |
| 1.5KE18CA | Through-hole DO-201 package, 1500 W rating, but larger footprint and no AEC-Q101 validation; VCL = 27.7 V at 43.3 A. | Requires board real estate and manual assembly; lacks automotive thermal cycling and vibration endurance testing. | Consider only for legacy through-hole designs where rework to SMT is impractical. |
Compared with SMAJ18CA and 1.5KE18CA, SM6T18CAY uniquely combines AEC-Q101 qualification, SMB form factor, 600 W surge capability, and 25.2 V clamping - making it the only choice for space-constrained, thermally demanding automotive power line protection requiring zero design compromise.
Availability
SM6T18CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS camera systems, and infotainment head units requiring stable component supply across automotive production lifecycles.
Supply support for SM6T18CAY 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, industrial, and power management solutions with vertical manufacturing and rigorous quality systems.
The SM6TY series targets automotive electronics protection, specifically engineered to meet ISO 7637-2, ISO 10605, and AEC-Q101 requirements for under-hood and cabin ECUs where reliability under thermal stress and electrical transients is non-negotiable.
FAQ
What is the maximum junction temperature for continuous operation?
The SM6T18CAY has a specified operating junction temperature range of −55 °C to +150 °C. At Tj = 150 °C, it maintains 515 W peak pulse power (10/1000 µs) and retains full AEC-Q101 qualification - confirmed in DS6905 Figure 3 and Table 1. This enables direct placement near high-heat sources like power MOSFETs or DC-DC inductors without derating concerns.
How does its bidirectional behavior affect PCB layout?
SM6T18CAY's symmetrical bidirectional structure eliminates polarity constraints: either terminal may connect to the protected line or ground. No orientation marking is required (see Figure 19), and the SMB footprint is identical for unidirectional and bidirectional variants - reducing inventory complexity and enabling single-footprint design reuse across multiple protection schemes.
Can it replace unidirectional TVS diodes in existing designs?
No - SM6T18CAY is strictly bidirectional and cannot substitute unidirectional types (e.g., SM6T18AY) in circuits requiring asymmetric clamping, such as DC power rails with defined ground reference. Its VBR and VCL values apply equally to both polarities, so using it on a unidirectional rail would allow unintended conduction during normal negative transients, risking system instability.
What is the significance of the "Y" suffix in the part number?
The "Y" suffix denotes STMicroelectronics' ECOPACK2-compliant packaging: matte tin plating meeting JESD 22-B102 E3, J-STD-002, and IPC7531 standards, with whisker resistance certified to JESD-201 Class 2. It also indicates tape-and-reel delivery (2500 pcs/reel) and full AEC-Q101 qualification - distinguishing it from commercial-grade variants lacking automotive validation.
SM6T18CAY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SM6TY, 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:
- 25.2V
- Current - Peak Pulse (10/1000µs):
- 24A
- Power - Peak Pulse:
- 600W
- 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:
- SMB
SM6T18CAY FAQ
1.How can I place an order for SM6T18CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM6T18CAY 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 SM6T18CAY reliable?
The price and inventory of SM6T18CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM6T18CAY is usually 5 days.
3.What payment methods are accepted for SM6T18CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM6T18CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM6T18CAY?
SM6T18CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM6T18CAY 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 SM6T18CAY?
For technical support, including SM6T18CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM6T18CAY requirements.
6.How does Aetrix verify that SM6T18CAY is sourced from the original manufacturer or authorized distributors?
All SM6T18CAY 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 SM6T18CAY meets industry standards.
7.What is the process for return or replacement of SM6T18CAY?
All SM6T18CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM6T18CAY, 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 SM6T18CAY part is unused and in its original packaging.
Return procedure for SM6T18CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM6T18CAY Tags
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