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STMicroelectronics SM4T35CAY
- Part No.:
- SM4T35CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T35CAY.pdf
- Description:
- TVS DIODE 30VWM 64.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:6,882
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Product details
Overview
SM4T35CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 pulse protection in 12 V vehicle power systems. It delivers 400 W peak pulse power (10/1000 µs), clamps at 48.4 V (max) under 8.3 A surge, and operates up to 150 °C junction temperature - deployed across engine control units, body electronics, and infotainment power rails.
For engineers reviewing the SM4T35CAY datasheet, SM4T35CAY pinout, SM4T35CAY application, or SM4T35CAY equivalent, key selection criteria include bidirectional clamping capability, 35 V breakdown voltage (VBR = 33.3–36.9 V), low dynamic resistance (RD = 0.762 Ω), compliance with ISO 10605 ESD (±30 kV), and SMA package thermal performance under automotive thermal cycling.
Technical Context
This device implements planar-junction silicon avalanche technology optimized for high-reliability automotive circuits requiring low leakage (<1 µA at 85 °C) and stable VBR over temperature (αT = 9.9 × 10−4/°C). Its bidirectional architecture enables symmetrical clamping on both polarities without external polarity management.
The SMA package supports JEDEC-standard reflow (peak 240–245 °C), meets UL94 V0 flammability, and provides defined thermal impedance (Zth(j-a) ≈ 100 °C/W on FR4 with recommended copper footprint), enabling predictable surge energy dissipation in constrained PCB layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 33.3 / 35.1 / 36.9 V - ensures reliable turn-on before downstream IC damage during load dump or inductive switching events |
| VCL @ IPP = 8.3 A | 48.4 V max - defines maximum voltage seen by protected circuit during 10/1000 µs surge |
| IRM @ VRM | 0.2 µA max at 25 °C - guarantees minimal standby current draw in always-on vehicle modules |
| PPP (10/1000 µs) | 400 W - sustains repeated transients per ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a/b |
| Tj operating range | −55 to +150 °C - validated for under-hood placement including transmission control units and ADAS sensor hubs |
| ESD rating (ISO 10605) | ±30 kV contact & air discharge - exceeds automotive ESD immunity requirements for exposed connectors and switches |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline with IPC-7531-compliant footprint and 72 mg unit weight |
Pinout & Package
SMA (DO-214AC) package: molded epoxy case, cathode band marking, 2-terminal unidirectional/bidirectional configuration. Dimensions per JEDEC MS-013AA: D = 2.25–2.90 mm, E = 4.80–5.35 mm, L = 0.75–1.50 mm, weight = 72 mg.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Surge current entry (bidirectional) | Accepts positive or negative transient energy; symmetric conduction enables single-device protection of AC-coupled or floating lines |
| Cathode | Surge current return path | Completes low-impedance path to ground or rail; marked with band; must connect to lowest-impedance reference plane for effective clamping |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive use across temperature, humidity, vibration, and lifetime reliability per stress test conditions |
| Bidirectional clamping | Eliminates need for dual-diode arrangements in differential or floating signal/power lines (e.g., LIN bus, CAN stubs) |
| Low dynamic resistance (RD) | 0.762 Ω - minimizes clamping voltage rise under high-current surges, preserving margin for 3.3 V/5 V logic interfaces |
| High Tj capability | 150 °C max operating junction temperature - supports placement near heat sources like power converters or motor drivers |
| UL94 V0 resin | Self-extinguishing encapsulation - satisfies automotive cabin and under-hood flammability safety standards |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus |
|---|---|
|
Use Scenario: Protects 12 V supply input against load dump (ISO 7637-2 Pulse 1: −150 V) and alternator ripple during battery disconnect. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC-DC converter input stage. Use Value: Limits transient voltage to ≤48.4 V, preventing damage to 60 V-rated input MOSFETs and maintaining system reset integrity. |
Use Scenario: Shields LIN transceiver pins from ESD events during connector mating/unmating and cable harness coupling. IC Role / Device Role / Timing Role: Bidirectional line protector on LIN data line (single-wire bus), referenced to local ground. Use Value: Clamps ±30 kV ESD pulses within 1 ns, preserving transceiver functionality without latch-up or parametric shift. |
| Infotainment Head Unit USB Port | ADAS Camera Power Rail |
|
Use Scenario: Guards 5 V USB VBUS line against hot-plug transients and conducted noise from vehicle battery system. IC Role / Device Role / Timing Role: Secondary surge suppressor after primary front-end filter, placed adjacent to USB controller IC. Use Value: Delivers 400 W pulse handling while maintaining <0.2 µA leakage at 25 °C, avoiding USB enumeration failures. |
Use Scenario: Safeguards 12 V camera module power input from ignition-induced spikes and electrostatic discharge in rear-view camera harnesses. IC Role / Device Role / Timing Role: First-line TVS on camera power feed, mounted directly at connector entry point. Use Value: Withstands −200 V ISO 7637-2 Pulse 3a and +150 V Pulse 3b without degradation over 10-year vehicle life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ33CA | Higher VBR (33–36.7 V), lower PPP (600 W), SMB package (larger footprint, higher Zth) | Less suitable for space-constrained automotive modules; requires larger copper pour for thermal management | Prefer when board area allows and higher clamping voltage margin is acceptable |
| 1.5KE36CA | Through-hole DO-201 package, 1500 W PPP, higher VCL (58.1 V), no AEC-Q101 qualification | Not automotive-qualified; unsuitable for production vehicles due to reliability and thermal cycling limitations | Only for non-automotive prototyping where cost outweighs qualification requirements |
Compared with SMBJ33CA and 1.5KE36CA, SM4T35CAY offers tighter VBR tolerance, AEC-Q101 validation, and SMA footprint compatibility with automated SMT assembly - critical for high-volume automotive electronics where thermal robustness, size, and qualification are non-negotiable.
Availability
SM4T35CAY is available at Aetrix Electronics and suitable for engine control units, body electronics modules, infotainment systems, and ADAS camera subsystems requiring stable component supply across extended automotive product lifecycles.
Supply support for SM4T35CAY 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, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.
SM4T35CAY belongs to the SM4TY series - a family of AEC-Q101-qualified TVS diodes engineered specifically for robust transient protection in 12 V automotive electrical systems compliant with ISO 7637-2 and ISO 10605.
FAQ
Is SM4T35CAY unidirectional or bidirectional?
SM4T35CAY is a bidirectional TVS diode, indicated by the "C" in its part number. It provides symmetrical clamping for both positive and negative transients, making it suitable for protecting AC-coupled signals, floating power domains, and differential buses like LIN without polarity concerns.
What is the maximum clamping voltage at 8.3 A surge current?
The maximum clamping voltage (VCL) for SM4T35CAY at 8.3 A (10/1000 µs waveform) is 48.4 V, measured at Tamb = 25 °C. This value increases with junction temperature at a coefficient of 9.9 × 10−4/°C, reaching ~51.2 V at Tj = 125 °C.
Does SM4T35CAY meet automotive qualification standards?
Yes - SM4T35CAY is AEC-Q101 qualified and fully compliant with ISO 7637-2 (Pulse 1, 2a, 3a, 3b) and ISO 10605 (±30 kV ESD) for automotive applications. It is rated for operation from −55 °C to +150 °C junction temperature and packaged in UL94 V0-compliant epoxy.
How does the SMA package affect thermal performance?
The SMA (DO-214AC) package delivers a thermal resistance of ~100 °C/W (junction-to-ambient) on standard FR4 with recommended 1.4 × 1.4 mm pad dimensions. Its compact size enables high-density layout, but effective heat spreading via copper pour beneath both terminals is essential to sustain repeated 400 W surges without exceeding 150 °C Tj.
SM4T35CAY 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):
- 30V
- Voltage - Breakdown (Min):
- 33.3V
- Voltage - Clamping (Max) @ Ipp:
- 64.3V
- Current - Peak Pulse (10/1000µs):
- 36A (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)
SM4T35CAY FAQ
1.How can I place an order for SM4T35CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T35CAY 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 SM4T35CAY reliable?
The price and inventory of SM4T35CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T35CAY is usually 5 days.
3.What payment methods are accepted for SM4T35CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T35CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T35CAY?
SM4T35CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T35CAY 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 SM4T35CAY?
For technical support, including SM4T35CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T35CAY requirements.
6.How does Aetrix verify that SM4T35CAY is sourced from the original manufacturer or authorized distributors?
All SM4T35CAY 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 SM4T35CAY meets industry standards.
7.What is the process for return or replacement of SM4T35CAY?
All SM4T35CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T35CAY, 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 SM4T35CAY part is unused and in its original packaging.
Return procedure for SM4T35CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T35CAY Tags
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