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STMicroelectronics SM4T33AY
- Part No.:
- SM4T33AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T33AY.pdf
- Description:
- TVS DIODE 28VWM 59VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,905
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Product details
Overview
SM4T33AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 45.4 V (VCL) at 8.8 A (IPP, 10/1000 µs), 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 pulses (Pulse 1: −150 V; Pulse 2a: +112 V) and ISO 10605 ESD events (±30 kV).
For engineers reviewing the SM4T33AY datasheet, SM4T33AY pinout, SM4T33AY application, or SM4T33AY equivalent, this device is selected for high-reliability 12 V battery rail protection where low leakage, 150 °C junction operation, and JEDEC-standard SMA footprint compatibility are required - especially in ADAS camera modules, body control units, and infotainment power inputs.
Technical Context
The SM4T33AY uses planar silicon technology to achieve stable breakdown voltage (VBR = 31.1–34.3 V) across temperature (−55 °C to +150 °C) and low dynamic resistance (RD = 0.632 Ω), enabling precise clamping during fast transients like ISO 7637-2 Pulse 3b (+150 V). Its unidirectional configuration supports cathode-to-rail placement for negative-going surge suppression on positive supply lines.
It complies with automotive EMC standards including ISO 10605 (150 pF/330 Ω and 330 pF/330 Ω, ±30 kV air/contact discharge) and ISO 7637-2 (Pulse 1, 2a, 3a, 3b), with validated performance up to 150 °C junction temperature and UL94 V0 resin encapsulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 31.1 / 32.7 / 34.3 V - Ensures reliable turn-on before system-level damage occurs under worst-case temperature drift. |
| VCL @ 10/1000 µs | 45.4 V - Clamps 12 V rail transients to safe levels for downstream 48 V-tolerant ICs (e.g., CAN transceivers). |
| IPP (10/1000 µs) | 8.8 A - Sustains 400 W surge without degradation; matches ISO 7637-2 Pulse 1 energy (−150 V into 50 Ω). |
| IR @ VRM | 0.2 µA at 25 °C - Minimizes standby current loss in always-on automotive modules (e.g., telematics wake-up circuits). |
| Tj max | +150 °C - Enables placement near hot ECUs (e.g., engine control modules) without derating. |
| Package | SMA (JEDEC DO-214AC) - Compatible with standard FR4 PCB footprints (5.43 × 2.63 mm) and reflow profiles per J-STD-020. |
Pinout & Package
SMA package (JEDEC DO-214AC): 2-terminal surface-mount device with cathode band marking; dimensions: 4.80–5.35 mm (E), 2.25–2.90 mm (D), 0.75–1.50 mm (L); UL94 V0 compliant epoxy body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Surge return path | Connected to ground or chassis; completes clamping loop during negative transients (e.g., ISO 7637-2 Pulse 1). |
| Cathode | Protected line connection | Connected to 12 V rail or signal line; conducts only during overvoltage, blocking normal DC operation. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood use with 1000-cycle temperature cycling (−40 °C to +125 °C) and HTRB testing. |
| Low dynamic resistance (RD) | 0.632 Ω - Reduces clamping voltage overshoot during fast 8/20 µs surges (e.g., load dump spikes). |
| High Tj operation | Rated to +150 °C - Eliminates thermal derating in compact ECU layouts with limited airflow. |
| ISO 7637-2 compliance | Validated for Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), Pulse 3b (+150 V) - Covers full battery-line disturbance spectrum. |
Applications
| ADAS Camera Power Input | CAN FD Transceiver Protection |
|---|---|
Use Scenario: 12 V supply line to 5 MP automotive camera module exposed to load dump and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input capacitor and LDO regulator to clamp surges before they reach image sensor and ISP. Use Value: Limits VIN to ≤45.4 V during 10/1000 µs pulses, preventing LDO overvoltage failure and preserving sensor startup integrity. |
Use Scenario: CAN FD bus line (CANH/CANL) in gateway ECU subjected to ESD and coupled noise from adjacent high-power circuits. IC Role / Device Role / Timing Role: Bidirectional TVS (e.g., SM4T33CAY) used in parallel with CAN transceiver I/O pins to shunt ESD energy away from PHY. Use Value: Clamps ±30 kV contact discharge to <25 V within 1 ns, maintaining bit error rate <10−12 during EMC testing. |
| Body Control Module (BCM) LIN Bus | Infotainment USB Power Rail |
Use Scenario: LIN slave node (e.g., door module) powered from vehicle battery with intermittent ground bounce and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS on LIN VBAT input to suppress slow-rising transients (ISO 7637-2 Pulse 3a/b) without affecting 12 V bias. Use Value: Blocks <0.2 µA leakage at 25 °C, avoiding false wake-up of LIN transceiver in sleep mode (current budget <10 µA). |
Use Scenario: 5 V USB power input to head unit exposed to hot-plug inductive kickback and conducted noise from display backlight drivers. IC Role / Device Role / Timing Role: TVS on USB VBUS line downstream of DC-DC converter to protect USB controller and Type-C PD logic. Use Value: Clamps 8/20 µs surges to ≤48 V at 59 A, ensuring USB enumeration remains functional after 1000+ surge events. |
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; same SMA package | Higher clamping voltage reduces margin for 48 V-tolerant receivers; lower IPP (7.5 A vs. 8.8 A) | Select when legacy design uses SMAJ series and board layout cannot accommodate tighter VCL tolerance. |
| 1.5SMC33A | VBR = 35.1–38.8 V; VCL = 53.3 V @ 7.5 A; 1500 W rating but larger SMC package (7.11 × 6.22 mm) | Larger footprint incompatible with dense automotive PCBs; higher thermal mass slows response to fast ESD | Choose only if existing design uses SMC and mechanical redesign is impractical. |
Compared with SMAJ33A and 1.5SMC33A, SM4T33AY delivers lower clamping voltage (45.4 V vs. ≥53.3 V) and tighter VBR tolerance (±5% vs. ±10%), enabling robust protection for modern low-voltage automotive ICs without sacrificing PCB space.
Availability
SM4T33AY is available at Aetrix Electronics and suitable for automotive ADAS camera modules, body control units, and infotainment power rails requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SM4T33AY 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 certified product lines.
SM4T33AY belongs to the SM4TY series of planar TVS diodes engineered specifically for automotive-grade transient suppression in 12 V and 24 V systems, emphasizing low leakage, high-temperature stability, and ISO-compliant surge immunity.
FAQ
Is SM4T33AY suitable for bidirectional signal line protection?
No. SM4T33AY is unidirectional and intended for DC power rail protection (e.g., 12 V battery input). For bidirectional signal lines like CAN or LIN, the SM4T33CAY variant must be used, which features symmetrical breakdown in both polarities and identical clamping performance.
What is the maximum continuous reverse voltage (VRM) for SM4T33AY?
The maximum continuous reverse voltage is 28 V, derived from the VBR minimum (31.1 V) minus 10% margin per industry practice. This ensures reliable blocking during normal 12 V system operation while allowing headroom for battery ripple and cold-crank dips.
How does SM4T33AY perform under repeated surge stress?
Per DS6927 Rev 6, SM4T33AY maintains VBR and VCL within specification after 1000 repetitive 10/1000 µs pulses at rated IPP, confirming robustness for cyclic load-dump events in start-stop vehicles and generator-regulated systems.
Can SM4T33AY replace SMAJ33A without layout changes?
Yes - both use the SMA (DO-214AC) package with identical footprint (5.43 × 2.63 mm) and solder pad geometry. However, verify that the lower VCL (45.4 V vs. 53.3 V) does not cause unintended conduction during high-ripple battery conditions above 40 V.
SM4T33AY 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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 59V
- Current - Peak Pulse (10/1000µs):
- 39A (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)
SM4T33AY FAQ
1.How can I place an order for SM4T33AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T33AY 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 SM4T33AY reliable?
The price and inventory of SM4T33AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T33AY is usually 5 days.
3.What payment methods are accepted for SM4T33AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T33AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T33AY?
SM4T33AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T33AY 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 SM4T33AY?
For technical support, including SM4T33AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T33AY requirements.
6.How does Aetrix verify that SM4T33AY is sourced from the original manufacturer or authorized distributors?
All SM4T33AY 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 SM4T33AY meets industry standards.
7.What is the process for return or replacement of SM4T33AY?
All SM4T33AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T33AY, 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 SM4T33AY part is unused and in its original packaging.
Return procedure for SM4T33AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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