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STMicroelectronics SM4T26CAY
- Part No.:
- SM4T26CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T26CAY.pdf
- Description:
- TVS DIODE 22VWM 48.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:1,132
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Product details
Overview
SM4T26CAY 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 26 V nominal breakdown voltage (VBR = 24.4–27 V), 35.5 V maximum clamping voltage at 11.2 A (8/20 µs), 400 W peak pulse power (10/1000 µs), and operates up to 150 °C junction temperature - deployed on engine control units, body control modules, and LIN/CAN node interfaces.
For engineers reviewing the SM4T26CAY datasheet, SM4T26CAY pinout, SM4T26CAY application, or SM4T26CAY equivalent, key selection criteria include unidirectional vs. bidirectional polarity, clamping voltage under 8/20 µs surge, dynamic resistance (0.444 Ω), leakage current at 85 °C (1 µA), and SMA package thermal performance per IPC 7531 footprint.
Technical Context
The SM4T26CAY uses planar silicon technology to achieve low leakage (<1 µA at 85 °C) and high thermal stability (Tjmax = 150 °C), enabling long-term reliability in under-hood automotive environments. Its bidirectional configuration supports symmetrical surge suppression for data lines like LIN or sensor inputs where polarity reversal may occur.
Clamping behavior follows VCL = VBR(max) + RD × IPP, with RD = 0.444 Ω confirmed at 25 °C. It meets ISO 10605 ESD immunity (±30 kV air/contact) and ISO 7637-2 transients including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 24.4 V / 25.7 V / 27 V - ensures reliable turn-on before downstream IC damage during load dump or inductive kick |
| VCL @ 11.2 A (8/20 µs) | 35.5 V - limits voltage seen by protected circuit during fast transients such as ESD or ignition noise |
| IPP (8/20 µs) | 48.3 A - sustains high-current surges without failure, validated per ISO 7637-2 Pulse 3b |
| RD (Dynamic Resistance) | 0.444 Ω - determines voltage overshoot slope; lower RD improves clamping linearity under high di/dt |
| IR @ VRM (85 °C) | 1 µA - minimizes standby power loss and signal distortion in high-impedance sensor interfaces |
| Tjmax | 150 °C - enables placement near heat sources (e.g., powertrain ECUs) without derating |
| Package | SMA (DO-214AC) - JEDEC-registered, UL94 V0 resin, compatible with automated SMT assembly and IPC 7531 footprint |
Pinout & Package
SMA (DO-214AC) package: surface-mount, two-terminal device with cathode band marking; dimensions per JEDEC MS-013 (EIAJ ED-4701), 2.25–2.90 mm width (D), 4.80–5.35 mm length (E), 1.90–2.45 mm height (A1). Compatible with standard reflow profiles (peak 240–245 °C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to GND or signal return; defines conduction path during negative transients (Pulse 1, Pulse 3a) |
| Cathode | High-side connection terminal | Connected to protected line (e.g., LIN bus); conducts during positive transients (Pulse 2a, Pulse 3b) and ESD events |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive use across temperature (-55 °C to +150 °C) and lifetime vibration/humidity stress |
| Bidirectional surge suppression | Protects AC-coupled or polarity-agnostic lines (e.g., LIN, analog sensor outputs) without external polarity management |
| Low dynamic resistance (0.444 Ω) | Reduces clamping voltage rise under high di/dt, critical for fast ISO 7637-2 pulses and ESD |
| UL94 V0 resin housing | Meets flammability safety requirements for enclosed automotive compartments and battery management zones |
| Planar junction construction | Enables stable leakage current (<1 µA at 85 °C) and predictable VBR drift over temperature (αT = 9.6 × 10−4/°C) |
Applications
| Engine Control Unit (ECU) Sensor Inputs | LIN Bus Node Protection |
|---|---|
|
Use Scenario: Protecting throttle position sensor (TPS) and manifold absolute pressure (MAP) analog inputs from alternator load dump and starter motor transients. IC Role / Device Role / Timing Role: Bidirectional TVS placed between signal line and chassis ground, clamping ±150 V transients within 1 ns response time. Use Value: Prevents ADC saturation and op-amp latch-up in 3.3 V/5 V signal chains while maintaining <1 µA leakage at 125 °C ambient. |
Use Scenario: Safeguarding LIN transceiver I/O pins against ESD (±30 kV) and battery line coupling during door module actuation. IC Role / Device Role / Timing Role: Low-capacitance (≈100 pF at 1 V) bidirectional clamp directly at connector interface, before LIN PHY input. Use Value: Maintains LIN signal integrity (20.2 kbaud) with <35.5 V clamping during 8/20 µs surges, avoiding false wake-up or communication timeout. |
| Body Control Module (BCM) Power Switches | Automotive Camera Power Rail |
|
Use Scenario: Suppressing inductive kickback from window lift motor drivers and seat actuator relays connected to 12 V supply rails. IC Role / Device Role / Timing Role: Parallel-mounted TVS on switched 12 V feed, absorbing Pulse 1 (−150 V) and Pulse 3b (+150 V) per ISO 7637-2. Use Value: Limits rail collapse to ≤35.5 V, preventing brownout reset of microcontrollers and preserving CAN/LIN gateway functionality. |
Use Scenario: Protecting 5 V camera module power input from reverse-battery connection and jump-start transients in rear-view systems. IC Role / Device Role / Timing Role: Unidirectional variant not applicable; SM4T26CAY used in dual-rail configurations where shared ground allows bidirectional clamping. Use Value: Withstands 400 W (10/1000 µs) surge energy without degradation, ensuring >10-year field life in stop/start cycling conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ26CA | Higher VCL = 42.1 V @ 9.5 A (8/20 µs); RD = 0.502 Ω; same SMA package | Less effective clamping margin for 3.3 V/5 V interfaces; suitable only where protected IC withstands >40 V transient | Select when cost sensitivity outweighs clamping performance; verify system-level VCL margin with worst-case IPP |
| SMBJ26CA | Same VBR/VCL specs but SMB package (larger footprint, higher thermal mass); 600 W rating (10/1000 µs) | Requires PCB area increase (~30% larger pad); better for high-volume thermal cycling but incompatible with dense LIN node layouts | Choose only if board space permits and thermal derating beyond 150 °C is required; not drop-in compatible |
Compared with SMAJ26CA and SMBJ26CA, SM4T26CAY delivers tighter clamping (35.5 V vs. 42.1 V), lower dynamic resistance (0.444 Ω vs. 0.502 Ω), and AEC-Q101 qualification out-of-box - making it optimal for space-constrained, high-reliability automotive nodes where voltage margin and leakage are design-critical.
Availability
SM4T26CAY is available at Aetrix Electronics and suitable for engine control units, LIN bus nodes, body control modules, and automotive camera power rails requiring stable component supply across automotive production lifecycles.
Supply support for SM4T26CAY 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 AEC-Q100/Q101 validation infrastructure.
The SM4Txx series belongs to ST's automotive transient protection portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle networks - emphasizing low leakage, high Tj, and planar junction reliability.
FAQ
Is SM4T26CAY unidirectional or bidirectional?
SM4T26CAY is a bidirectional TVS diode, indicated by the "C" in its part number (per ST's ordering convention: "AY" = unidirectional, "CAY" = bidirectional). It provides symmetrical clamping for both positive and negative transients, making it suitable for AC-coupled or polarity-agnostic signal lines such as LIN bus or differential sensor outputs.
What is the maximum clamping voltage at 8/20 µs surge current?
The maximum clamping voltage (VCL) for SM4T26CAY is 35.5 V at 48.3 A peak pulse current under an 8/20 µs waveform, as specified in Table 2 of DS6927 Rev 6. This value is measured at Tamb = 25 °C and defines the upper voltage limit imposed on protected circuitry during fast transients.
Does SM4T26CAY meet AEC-Q101 requirements?
Yes, SM4T26CAY is explicitly qualified to AEC-Q101 Rev D for discrete semiconductors. The datasheet states AEC-Q101 qualification in the Features section and confirms operating junction temperature range of −55 °C to +150 °C, along with stress test compliance for humidity, temperature cycling, and mechanical shock per automotive standards.
Can SM4T26CAY replace SMAJ26CA in existing designs?
No - although both are bidirectional 26 V TVS diodes in SMA packages, SM4T26CAY has lower VCL (35.5 V vs. 42.1 V) and lower RD (0.444 Ω vs. 0.502 Ω), meaning it clamps more tightly. Substitution requires verification of protected IC's absolute maximum ratings and layout parasitics, as tighter clamping may increase peak current stress on upstream traces or fuses.
SM4T26CAY 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):
- 22V
- Voltage - Breakdown (Min):
- 24.4V
- Voltage - Clamping (Max) @ Ipp:
- 48.3V
- Current - Peak Pulse (10/1000µs):
- 48A (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)
SM4T26CAY FAQ
1.How can I place an order for SM4T26CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T26CAY 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 SM4T26CAY reliable?
The price and inventory of SM4T26CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T26CAY is usually 5 days.
3.What payment methods are accepted for SM4T26CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T26CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T26CAY?
SM4T26CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T26CAY 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 SM4T26CAY?
For technical support, including SM4T26CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T26CAY requirements.
6.How does Aetrix verify that SM4T26CAY is sourced from the original manufacturer or authorized distributors?
All SM4T26CAY 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 SM4T26CAY meets industry standards.
7.What is the process for return or replacement of SM4T26CAY?
All SM4T26CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T26CAY, 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 SM4T26CAY part is unused and in its original packaging.
Return procedure for SM4T26CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T26CAY Tags
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