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STMicroelectronics SM4T33CAY
- Part No.:
- SM4T33CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T33CAY.pdf
- Description:
- TVS DIODE 28VWM 59VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:13,189
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Product details
Overview
SM4T33CAY 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 33 V nominal breakdown voltage (VBR = 31.1–34.3 V), 45.4 V maximum clamping voltage at 8.8 A (10/1000 µs), 59 A peak pulse current (8/20 µs), and AEC-Q101 qualification for under-hood reliability.
For engineers reviewing the SM4T33CAY datasheet, SM4T33CAY pinout, SM4T33CAY application, or SM4T33CAY equivalent, this device is selected for robust ESD and surge protection in CAN/LIN bus interfaces, body control modules, and infotainment power rails where low leakage (<1 µA @ 85 °C), high Tj (150 °C), and SMA footprint compatibility are critical.
Technical Context
The SM4T33CAY employs planar junction technology to achieve stable VBR temperature coefficient (αT = 9.8 × 10−4/°C) and low dynamic resistance (RD = 0.632 Ω). Its bidirectional structure enables symmetrical clamping for both positive and negative transients without polarity constraints.
It meets ISO 10605 ESD immunity (±30 kV air/contact discharge) and ISO 7637-2 automotive surge requirements including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V), with full compliance verified at Tj up to 150 °C.
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 damage during 12 V battery-line surges |
| VCL @ IPP (10/1000 µs) | 45.4 V @ 8.8 A - Limits downstream IC voltage to safe level during slow-rising load-dump events |
| VCL @ IPP (8/20 µs) | 59 V @ 39 A - Clamps fast ESD and ignition noise spikes within automotive EMC limits |
| IR @ VRM | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Prevents signal integrity degradation in high-impedance sensor inputs |
| PPP (10/1000 µs) | 400 W - Sustains repeated load-dump pulses without thermal runaway in engine control units |
| Tj max | 150 °C - Enables placement near heat sources (e.g., power relays, motor drivers) without derating |
| Package | SMA (DO-214AC) - Industry-standard surface-mount outline compatible with IPC-7531 footprints |
Pinout & Package
SMA package (DO-214AC) per JEDEC MS-013AC, with cathode band marking on one end; dual-terminal construction supports bidirectional surge conduction without polarity orientation dependency.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode (symmetrical) | Bidirectional transient path | Either terminal serves as input/output; no DC polarity requirement for surge suppression |
| Cathode band (marked end) | Manufacturing reference mark | Indicates terminal location only; functionally identical to opposite terminal in bidirectional mode |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use across −55 °C to +150 °C junction temperature range |
| Low leakage current | ≤1 µA at 85 °C ensures minimal power loss and signal distortion in always-on circuits |
| ISO 7637-2 Pulse 1/2a/3a/3b compliance | Rated for −150 V (P1), +112 V (P2a), −200 V (P3a), +150 V (P3b) - covers all major automotive surge profiles |
| UL94 V0 resin housing | Self-extinguishing encapsulation prevents flame propagation in enclosed ECUs |
| Planar junction technology | Enables tight VBR tolerance and stable RD over lifetime, critical for long-term field reliability |
Applications
| Body Control Module (BCM) | CAN Bus Interface |
|---|---|
Use Scenario: Protecting microcontroller I/O and power supply pins from battery line transients during door lock actuation or lighting load switching. IC Role / Device Role / Timing Role: Bidirectional TVS clamp placed between 12 V rail and ground, absorbing Pulse 1 (−150 V) and Pulse 3b (+150 V) energy. Use Value: Prevents latch-up or permanent damage to 3.3 V/5 V logic supplies while maintaining <1 µA standby leakage. |
Use Scenario: Shielding CANH/CANL differential pair against ESD events during connector mating/unmating in infotainment head units. IC Role / Device Role / Timing Role: Low-capacitance bidirectional TVS placed across CANH–CANL, clamping ±30 kV contact discharge per ISO 10605. Use Value: Maintains signal integrity below 100 pF capacitance and avoids bit errors during 1 Mbps CAN FD operation. |
| Powertrain Sensor Interface | Automotive Lighting Driver |
Use Scenario: Safeguarding oxygen sensor analog front-end from ignition coil coupling noise in engine control units. IC Role / Device Role / Timing Role: High-Tj TVS mounted adjacent to sensor conditioning circuitry, suppressing 8/20 µs spikes up to 59 V. Use Value: Enables continuous operation at 150 °C ambient without VBR drift exceeding ±5 %, ensuring calibration stability. |
Use Scenario: Protecting LED driver IC power inputs from alternator load dump in adaptive front-lighting systems. IC Role / Device Role / Timing Role: 400 W peak power TVS placed at 12 V input stage, handling 10/1000 µs surges up to 45.4 V clamping. Use Value: Absorbs 150 ms load-dump energy without thermal failure, eliminating need for external heatsinking. |
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 VCL (53.3 V @ 8/20 µs), lower PPP (600 W), SMB package (larger footprint) | Less suitable for space-constrained PCBs; higher clamping may stress downstream 3.3 V logic | Prefer when board layout allows SMB and higher clamping voltage is acceptable |
| 1.5KE33CA | Through-hole DO-201 package, 1500 W PPP, higher IR (5 µA @ 85 °C) | Not AEC-Q101 qualified; unsuitable for automotive production due to reliability and mounting constraints | Only for non-automotive prototyping or industrial backup designs |
Compared with SMBJ33CA and 1.5KE33CA, SM4T33CAY delivers tighter VBR tolerance, lower leakage, AEC-Q101 validation, and SMA footprint-making it the optimal choice for production automotive electronics requiring compact, high-reliability surge protection.
Availability
SM4T33CAY is available at Aetrix Electronics and suitable for body control modules, CAN bus interfaces, powertrain sensor subsystems, and automotive lighting drivers requiring stable component supply across extended temperature and surge environments.
Supply support for SM4T33CAY 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-Q100/101 certified processes.
The SM4Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle networks-prioritizing low leakage, high Tj, and planar-junction reliability.
FAQ
Is SM4T33CAY unidirectional or bidirectional?
SM4T33CAY is a bidirectional TVS diode, indicated by the "C" in its part number. It provides symmetrical clamping for both positive and negative transients without requiring polarity-specific placement on the PCB, making it ideal for differential lines like CANH/CANL or AC-coupled signals.
What is the maximum operating junction temperature?
The SM4T33CAY has a rated operating junction temperature range of −55 °C to +150 °C, validated per AEC-Q101. This allows direct placement near heat-generating components such as power MOSFETs or motor drivers in engine compartments without thermal derating.
Does SM4T33CAY meet ISO 7637-2 Pulse 1 requirements?
Yes-SM4T33CAY is explicitly rated for ISO 7637-2 Pulse 1 (−150 V, 50 Ω source impedance, 12 V battery), with clamping performance verified at 45.4 V (10/1000 µs) and 59 V (8/20 µs), ensuring protected circuits remain below 60 V during worst-case load-dump events.
How does SM4T33CAY differ from SM4T33AY?
SM4T33AY is the unidirectional version (anode-to-cathode conduction only), while SM4T33CAY is bidirectional (conduction in both directions). The "C" suffix denotes bidirectionality; both share identical VBR, VCL, and package but differ in polarity-sensitive placement and application scope-e.g., SM4T33CAY is mandatory for CAN bus protection.
SM4T33CAY 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):
- 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)
SM4T33CAY FAQ
1.How can I place an order for SM4T33CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T33CAY 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 SM4T33CAY reliable?
The price and inventory of SM4T33CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T33CAY is usually 5 days.
3.What payment methods are accepted for SM4T33CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T33CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T33CAY?
SM4T33CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T33CAY 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 SM4T33CAY?
For technical support, including SM4T33CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T33CAY requirements.
6.How does Aetrix verify that SM4T33CAY is sourced from the original manufacturer or authorized distributors?
All SM4T33CAY 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 SM4T33CAY meets industry standards.
7.What is the process for return or replacement of SM4T33CAY?
All SM4T33CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T33CAY, 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 SM4T33CAY part is unused and in its original packaging.
Return procedure for SM4T33CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T33CAY Tags
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