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STMicroelectronics SM4T35AY
- Part No.:
- SM4T35AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T35AY.pdf
- Description:
- TVS DIODE 30VWM 64.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:6,692
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Product details
Overview
SM4T35AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 48.4 V (VCL) at 8.3 A (IPP) under 10/1000 µs waveform, with 400 W peak pulse power rating and 0.2 µA leakage at 25 °C. It protects CAN, LIN, and sensor interfaces in 12 V automotive systems against ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), and ISO 10605 ESD events.
For engineers reviewing the SM4T35AY datasheet, SM4T35AY pinout, SM4T35AY application, or SM4T35AY equivalent, this device is selected for robust front-end surge protection in battery-supplied ECUs where low leakage, high Tj (150 °C), and JEDEC-standard SMA footprint are mandatory design constraints.
Technical Context
The SM4T35AY operates as a unidirectional clamping diode with breakdown voltage VBR = 33.3–36.9 V (min–max at 25 °C) and dynamic resistance RD = 0.762 Ω, enabling precise voltage limiting during fast transients. Its planar silicon construction ensures stable leakage performance across −55 to +150 °C junction temperature range.
It complies with ISO 7637-2 (Pulse 1, 2a, 3a, 3b) and ISO 10605 (150 pF/330 Ω and 330 pF/330 Ω) standards, delivering 30 kV air/contact ESD immunity and surviving −150 V load dump pulses without degradation - critical for engine control, body electronics, and ADAS sensor nodes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 33.3 / 35.1 / 36.9 V - defines minimum clamping onset threshold across production lot and temperature |
| VCL @ 10/1000 µs | 48.4 V - maximum clamped voltage seen by protected IC during 10/1000 µs surge, limiting stress on downstream logic |
| IPP @ 10/1000 µs | 8.3 A - peak surge current handled without failure, supporting ≥400 W pulse power dissipation |
| IR @ VRM | 0.2 µA at 25 °C - ultra-low reverse leakage preserves battery life in always-on automotive modules |
| Tj max | +150 °C - enables placement near heat sources (e.g., power stages) without derating |
| Package | SMA (DO-214AC) - JEDEC-registered surface-mount outline with 5.35 mm × 4.60 mm footprint, compatible with standard reflow profiles |
Pinout & Package
SMA package: molded plastic case with two coplanar J-bend leads; dimensions per JEDEC DO-214AC (EIAJ ED-732AA), 5.35 mm length × 4.60 mm width × 2.45 mm height; UL94 V-0 rated epoxy resin.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked band) | Surge return path | Connected to ground or low-impedance reference; carries full transient current during clamping |
| Anode | Protected line input | Connected to signal/power line (e.g., CAN_H); reverse-biased during normal operation, avalanches during overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive underhood use including temperature cycling, humidity bias, and mechanical shock per stress test requirements |
| Low dynamic resistance (RD) | 0.762 Ω - minimizes VCL rise under high IPP, improving protection margin for 3.3 V/5 V interface ICs |
| High-temperature leakage stability | 1 µA max at 85 °C - ensures no signal integrity degradation in hot-cabin infotainment or powertrain modules |
| ISO 7637-2 Pulse 1 survivability | Withstands −150 V load dump at 50 Ω source impedance - protects against alternator disconnection events in 12 V systems |
Applications
| Engine Control Unit (ECU) Power Input | CAN FD Transceiver Protection |
|---|---|
Use Scenario: Installed across battery rail (VBAT) and chassis ground in diesel/gasoline engine control units to suppress load dump transients. IC Role / Device Role / Timing Role: Unidirectional TVS clamping device placed upstream of DC-DC converter input to limit voltage excursion during alternator field decay. Use Value: Prevents >60 V spikes from damaging 40 V-rated input MOSFETs and LDO regulators, extending system lifetime beyond 15-year vehicle service life. | Use Scenario: Mounted on CAN_H/CAN_L lines of automotive gateway modules operating at 5 Mbit/s CAN FD data rates. IC Role / Device Role / Timing Role: Low-capacitance (<100 pF) transient suppressor that maintains signal integrity while absorbing ESD and coupled noise. Use Value: Enables reliable communication during 30 kV contact discharge events without bit errors or bus lockup, meeting OEM EMC validation requirements. |
| Body Control Module (BCM) Sensor Interface | ADAS Camera Power Line |
Use Scenario: Protecting LIN bus and analog sensor inputs (e.g., ambient temperature, rain sensor) in door modules and lighting controllers. IC Role / Device Role / Timing Role: Standoff voltage (VRM = 30 V) matches 24 V HVAC actuators and 12 V interior sensors; clamps within 10 ns response time. Use Value: Eliminates false triggers and calibration drift caused by 12 V supply transients, reducing warranty claims for intermittent sensor faults. | Use Scenario: Placed on 12 V power feed to 8 MP automotive camera modules mounted behind rearview mirrors. IC Role / Device Role / Timing Role: First-line defense against ISO 7637-2 Pulse 3b (+150 V) induced by nearby solenoid switching in ADAS domain controllers. Use Value: Prevents image sensor latch-up and FPGA configuration corruption during automated parking maneuvers, ensuring ASIL-B functional safety compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ33A | VBR = 36.7–40.6 V; VCL = 53.3 V @ 7.5 A; RD = 0.884 Ω - higher clamping voltage and lower IPP | Less margin for 3.3 V logic interfaces; requires larger PCB area due to SMAJ's taller profile (2.79 mm vs. SM4T's 2.45 mm) | Select when legacy layout compatibility with SMAJ footprint is required and VCL margin >5 V is acceptable |
| 1.5SMC33A | VBR = 36.7–40.6 V; VCL = 53.3 V @ 7.5 A; 1500 W rating - higher power but larger SMC package (7.11 mm × 6.22 mm) | Not suitable for space-constrained ADAS camera modules; thermal resistance 1.5× higher than SMA, limiting high-frequency surge repetition | Choose only for non-automotive industrial applications where AEC-Q101 is not mandated and board space permits SMC |
Compared with SMAJ33A and 1.5SMC33A, SM4T35AY delivers tighter VBR tolerance (±5.3% vs. ±10.5%), lower VCL (48.4 V vs. 53.3 V), and AEC-Q101 certification - making it the optimal choice for next-generation compact, high-reliability automotive electronics.
Availability
SM4T35AY is available at Aetrix Electronics and suitable for engine control units, CAN FD gateways, body control modules, and ADAS camera power supplies requiring stable component supply across multi-year automotive production programs.
Supply support for SM4T35AY 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.
The SM4TxxAY series belongs to ST's automotive-grade transient voltage suppression portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V/24 V vehicle electrical architectures.
FAQ
What is the maximum clamping voltage of SM4T35AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 48.4 V at 8.3 A peak pulse current under the 10/1000 µs waveform, measured at Tamb = 25 °C. This value increases linearly with junction temperature at αT = 9.9 × 10−4/°C, reaching ~51.2 V at Tj = 125 °C per the datasheet's temperature coefficient formula.
Is SM4T35AY bidirectional or unidirectional?
SM4T35AY is a unidirectional TVS diode, indicated by the "AY" suffix (vs. "CAY" for bidirectional). It conducts only during negative transients on the anode relative to cathode, making it suitable for DC power line and single-polarity signal protection like CAN_H or LIN bus.
Can SM4T35AY replace SM4T33AY in existing designs?
Yes, with verification: SM4T35AY has VBR = 33.3–36.9 V versus SM4T33AY's 31.1–34.3 V, resulting in ~2 V higher standoff and clamping. This provides additional margin against false triggering but requires confirming downstream ICs tolerate the higher VCL of 48.4 V versus 45.4 V.
What is the recommended PCB footprint for SM4T35AY?
The recommended footprint matches JEDEC DO-214AC (SMA): 5.43 mm pad length × 1.40 mm pad width × 1.64 mm center-to-center spacing, with 2.63 mm solder mask opening per pad. Thermal relief via copper pour under the body improves power dissipation during repetitive surges per Figure 12 in DS6927.
SM4T35AY 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:
- 1
- Bidirectional Channels:
- -
- 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)
SM4T35AY FAQ
1.How can I place an order for SM4T35AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T35AY 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 SM4T35AY reliable?
The price and inventory of SM4T35AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T35AY is usually 5 days.
3.What payment methods are accepted for SM4T35AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T35AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T35AY?
SM4T35AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T35AY 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 SM4T35AY?
For technical support, including SM4T35AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T35AY requirements.
6.How does Aetrix verify that SM4T35AY is sourced from the original manufacturer or authorized distributors?
All SM4T35AY 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 SM4T35AY meets industry standards.
7.What is the process for return or replacement of SM4T35AY?
All SM4T35AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T35AY, 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 SM4T35AY part is unused and in its original packaging.
Return procedure for SM4T35AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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