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STMicroelectronics SM4T30CAY
- Part No.:
- SM4T30CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T30CAY.pdf
- Description:
- TVS DIODE 26VWM 53.5VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:5,284
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Product details
Overview
SM4T30CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 and ISO 10605 surge/ESD protection in 12 V vehicle power networks. It features a 30.4 V nominal breakdown voltage (VBR), 42.1 V maximum clamping voltage (VCL) at 9.5 A (10/1000 µs), 400 W peak pulse power, and AEC-Q101 qualification for under-hood reliability.
For engineers reviewing the SM4T30CAY datasheet, SM4T30CAY pinout, SM4T30CAY application, or SM4T30CAY equivalent, this device is selected for robust bidirectional overvoltage protection in automotive body control modules, infotainment power rails, and LIN/CAN transceiver interfaces where low leakage (<1 µA @ 85 °C), high Tj (150 °C), and SMA footprint compatibility are critical.
Technical Context
The SM4T30CAY uses planar junction technology to achieve stable VBR temperature coefficient (αT = 9.7 × 10−4/°C) and low dynamic resistance (RD = 0.502 Ω), enabling precise clamping across −55 °C to +150 °C operating range. Its bidirectional structure provides symmetrical surge response for both positive and negative transients without polarity dependency.
It meets ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V) requirements for 12 V systems, and delivers 30 kV ESD immunity per ISO 10605 (150 pF/330 Ω and 330 pF/330 Ω configurations), with junction capacitance <100 pF at 0 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 28.9 / 30.4 / 31.9 V - Ensures reliable turn-on before system damage during slow-rising surges |
| VCL @ 9.5 A (10/1000 µs) | 42.1 V - Limits downstream IC voltage stress to safe levels during load-dump events |
| Peak pulse power (10/1000 µs) | 400 W - Sustains automotive-level transient energy without thermal runaway |
| IRM @ VRM = 26 V | 0.2 µA @ 25 °C / 1 µA @ 85 °C - Minimizes standby current drain in always-on vehicle circuits |
| Tj max | +150 °C - Supports placement near heat sources (e.g., engine control units) without derating |
| Package | SMA (DO-214AC) - Industry-standard surface-mount outline compliant with IPC 7531 and JEDEC MO-136 |
| AEC-Q101 qualified | Yes - Validated for automotive use including temperature cycling, humidity bias, and mechanical shock |
Pinout & Package
SMA package (DO-214AC): 2-terminal surface-mount device with cathode band marking; dimensions per JEDEC MO-136 (A2 = 0.05–0.20 mm, D = 2.25–2.90 mm, E = 4.80–5.35 mm, L = 0.75–1.50 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side terminal (bidirectional) | Connects to protected line; conducts during negative transients and reverse-biased during positive surges |
| Cathode | High-side terminal (bidirectional) | Connects to ground or reference rail; conducts during positive transients and reverse-biased during negative surges |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional surge suppression | Enables single-device protection of AC-coupled or floating signal lines (e.g., LIN bus, sensor outputs) |
| Low dynamic resistance (0.502 Ω) | Reduces clamping voltage overshoot during fast 8/20 µs transients (e.g., ISO 7637-2 Pulse 3b) |
| Planar junction construction | Delivers stable leakage and VBR over temperature-critical for long-term reliability in sealed ECUs |
| UL94 V0-compliant resin | Meets flammability requirements for interior and engine compartment mounting locations |
| ISO 10605 ESD rating | 30 kV air/contact discharge - exceeds automotive OEM requirements for touch-sensitive modules |
Applications
| Body Control Module (BCM) | Infotainment Power Rail |
|---|---|
|
Use Scenario: Protecting 12 V supply input of BCM microcontrollers and CAN transceivers against load dump and jump-start surges. IC Role / Device Role / Timing Role: Bidirectional TVS clamp placed between battery rail and local DC-DC input, absorbing energy within 100 ns. Use Value: Prevents latch-up or permanent damage to 3.3 V/5 V logic supplies during −150 V Pulse 1 events. |
Use Scenario: Safeguarding USB-C and HDMI power delivery lines in head units exposed to ESD during user interaction. IC Role / Device Role / Timing Role: Low-capacitance TVS on VBUS and CC lines, responding to 150 pF/330 Ω contact discharge in <1 ns. Use Value: Maintains signal integrity below 100 pF while suppressing 30 kV ESD without false triggering. |
| LIN Transceiver Interface | Engine Coolant Temperature Sensor |
|
Use Scenario: Shielding LIN bus pins from coupled transients induced by nearby solenoid switching in powertrain subsystems. IC Role / Device Role / Timing Role: Bidirectional TVS connected between LIN data line and chassis ground, clamping ±112 V Pulse 2a spikes. Use Value: Preserves LIN communication integrity during cranking events without adding propagation delay. |
Use Scenario: Protecting analog output of NTC-based coolant sensors mounted near exhaust manifolds. IC Role / Device Role / Timing Role: High-Tj TVS on sensor signal line, operating continuously at 150 °C ambient with <1 µA leakage. Use Value: Eliminates measurement drift caused by thermally accelerated leakage current in harsh under-hood environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ30CA | Higher VCL (48.4 V @ 8.3 A), lower PPP (600 W), SMB package (larger footprint) | Less suitable for space-constrained PCBs; higher clamping increases risk to 3.3 V logic interfaces | Prefer SM4T30CAY when board area is limited and clamping voltage margin is tight |
| 1.5KE30CA | Through-hole DO-201 package, higher VCL (49.9 V), slower response due to parasitic inductance | Not AEC-Q101 qualified; unsuitable for automotive production; requires manual assembly | SM4T30CAY is required for automated SMT lines and OEM compliance documentation |
Compared with SMBJ30CA and 1.5KE30CA, SM4T30CAY offers superior thermal performance (150 °C Tj), tighter VCL tolerance (42.1 V vs. ≥48 V), and AEC-Q101 validation-making it the only choice for safety-critical automotive SMT designs requiring zero rework risk.
Availability
SM4T30CAY is available at Aetrix Electronics and suitable for automotive body electronics, infotainment power management, and sensor interface protection requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM4T30CAY 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 validation expertise.
The SM4Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V/24 V vehicle networks-prioritizing low leakage, high Tj, and planar junction stability.
FAQ
What is the difference between SM4T30AY and SM4T30CAY?
SM4T30AY is unidirectional (anode-to-cathode conduction only), while SM4T30CAY is bidirectional-capable of clamping both positive and negative transients symmetrically. The 'C' suffix denotes bidirectional functionality, essential for AC-coupled or floating signal lines like LIN or sensor outputs where polarity reversal occurs.
Can SM4T30CAY be used in 24 V commercial vehicle systems?
No-SM4T30CAY is rated for 12 V automotive systems (VRM = 26 V). For 24 V applications, ST recommends SM4T47CAY (VRM = 40 V) or SM4T56CAY (VRM = 48 V), which maintain adequate standoff margin above nominal battery voltage and meet ISO 7637-2 Pulse 1 (−200 V) requirements for heavy-duty vehicles.
Does SM4T30CAY require a heatsink for 400 W pulse handling?
No external heatsink is needed-the 400 W rating applies to single 10/1000 µs pulses with Tj initial = 25 °C. Thermal impedance (Zth(j-a)) is 40 °C/W on standard FR4 with 1.4 mm² copper per pad; sustained repetitive surges require layout optimization but not added thermal mass.
How does the 9.7 × 10−4/°C temperature coefficient affect VBR in real operation?
At 125 °C junction temperature, VBR increases by ~9.7% over its 25 °C value (30.4 V → ~33.4 V), ensuring turn-on remains safely above normal operating voltage even under extreme under-hood conditions-preventing false triggering during hot cranking or prolonged idling.
SM4T30CAY 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):
- 26V
- Voltage - Breakdown (Min):
- 28.9V
- Voltage - Clamping (Max) @ Ipp:
- 53.5V
- Current - Peak Pulse (10/1000µs):
- 43A (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)
SM4T30CAY FAQ
1.How can I place an order for SM4T30CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T30CAY 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 SM4T30CAY reliable?
The price and inventory of SM4T30CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T30CAY is usually 5 days.
3.What payment methods are accepted for SM4T30CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T30CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T30CAY?
SM4T30CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T30CAY 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 SM4T30CAY?
For technical support, including SM4T30CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T30CAY requirements.
6.How does Aetrix verify that SM4T30CAY is sourced from the original manufacturer or authorized distributors?
All SM4T30CAY 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 SM4T30CAY meets industry standards.
7.What is the process for return or replacement of SM4T30CAY?
All SM4T30CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T30CAY, 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 SM4T30CAY part is unused and in its original packaging.
Return procedure for SM4T30CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T30CAY Tags
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