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STMicroelectronics SM4T30AY
- Part No.:
- SM4T30AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T30AY.pdf
- Description:
- TVS DIODE 26VWM 53.5VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:4,983
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Product details
Overview
SM4T30AY from STMicroelectronics is a unidirectional automotive-grade transient voltage suppression diode designed to protect 12 V and 24 V automotive power lines against ISO 7637-2 pulses (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −200 V; Pulse 3b: +150 V) and ISO 10605 ESD events (±30 kV air/contact). 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 operates up to 150 °C junction temperature.
For engineers reviewing the SM4T30AY datasheet, SM4T30AY pinout, SM4T30AY application, or SM4T30AY equivalent, this device is selected for robust front-end protection in automotive body control modules, infotainment power supplies, and ADAS sensor interfaces where low leakage (<0.2 µA @ 25 °C), AEC-Q101 qualification, and SMA footprint compatibility are critical.
Technical Context
The SM4T30AY employs planar silicon junction technology optimized for high-temperature reliability and minimal reverse leakage across −55 °C to +150 °C operating range. Its dynamic resistance (RD = 0.502 Ω) and clamping behavior are characterized under both 10/1000 µs (IEC 61000-4-5) and 8/20 µs (IEC 61000-4-5 fast surge) waveforms.
It complies with ISO 7637-2 for automotive transients and ISO 10605 for ESD immunity, supporting system-level compliance without external filtering. The unidirectional configuration enables DC-biased line protection with forward conduction capability during negative transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 28.9 / 30.4 / 31.9 V - ensures reliable turn-on above normal 24 V rail with margin against ripple and tolerance |
| VCL @ 9.5 A (10/1000 µs) | 42.1 V - limits downstream IC stress during load dump surges in 24 V systems |
| PPP (10/1000 µs) | 400 W - sustains ISO 7637-2 Pulse 1 and Pulse 3b without degradation |
| IR @ VRM = 26 V | 0.2 µA @ 25 °C - prevents battery drain in always-on automotive circuits |
| Tj max | +150 °C - supports placement near hot engine-control units or power converters |
| Dynamic Resistance RD | 0.502 Ω - determines VCL rise slope under high-current transients (ΔV = I × RD) |
| ESD Rating | ±30 kV (ISO 10605, 150 pF/330 Ω) - exceeds automotive touch-point immunity requirements |
Pinout & Package
SM4T30AY is housed in an industry-standard SMA (DO-214AC) package per JEDEC MS-013, with cathode band marking and UL94 V0-compliant epoxy resin. The package measures 4.80–5.35 mm (E) × 2.25–2.90 mm (D) × 0.75–1.50 mm (L), compatible with IPC-7531 footprint guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Ground reference terminal for unidirectional clamping | Connected to chassis or system ground; conducts surge current to earth during negative transients |
| Cathode | Protected line input terminal | Connected to 24 V supply rail; blocks reverse leakage until VBR exceeded, then clamps positive overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood environments including thermal cycling, humidity, and mechanical shock |
| Low Tj-dependent leakage | 0.2 µA @ 25 °C and 1 µA @ 85 °C - preserves sleep-mode current budget in always-on ECUs |
| Planar junction construction | Enables stable VBR and RD over lifetime, minimizing parameter drift in high-temperature operation |
| SMA footprint compatibility | Matches IPC-7531 standard - allows drop-in replacement and automated assembly on existing PCBs |
| UL94 V0 resin encapsulation | Meets flammability safety requirements for enclosed automotive electronics compartments |
Applications
| Body Control Module (BCM) | Infotainment Power Supply |
|---|---|
Use Scenario: Protects 24 V input of BCM microcontroller power rails against load dump and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery feed and LDO input to clamp surges before regulation. Use Value: Limits VCL to 42.1 V at 9.5 A, preventing LDO overvoltage failure and ensuring MCU reset integrity during ISO 7637-2 Pulse 1. | Use Scenario: Shields USB-C PD controller and audio codec power inputs from ESD events during user interface interaction. IC Role / Device Role / Timing Role: Front-end ESD suppressor on 5 V/12 V auxiliary rails, rated for ±30 kV contact discharge. Use Value: Sub-µA leakage avoids standby current increase; 0.502 Ω RD ensures fast clamping response within <1 ns to preserve signal integrity. |
| ADAS Camera Module | Electric Power Steering (EPS) |
Use Scenario: Guards MIPI CSI-2 power and I/O lines in rear-view camera against cable-induced transients during vehicle motion. IC Role / Device Role / Timing Role: Localized TVS on FPC connector side, co-located with ferrite beads for combined ESD/surge filtering. Use Value: 150 °C Tj max enables mounting directly on camera PCB near heat-generating image sensor without derating. | Use Scenario: Protects motor driver gate-drive supply and CAN transceiver VCC from battery reversal and alternator ripple spikes. IC Role / Device Role / Timing Role: Bidirectional-capable unidirectional TVS used in dual-rail configuration for isolated 12 V logic and 24 V motor power domains. Use Value: 400 W 10/1000 µs rating withstands repeated Pulse 3a (−200 V) events during EPS calibration cycles without parametric shift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ30A | Higher VCL (48.4 V @ 8.3 A), lower PPP (400 W same, but lower IPP capability), non-AEC-Q101 | Not qualified for automotive underhood use; suitable only for industrial/commercial 24 V systems | Select when AEC-Q101 is not required and cost is prioritized over long-term reliability in hot environments |
| 1.5SMC33A | Higher VBR (33.2–36.8 V), higher VCL (53.3 V), larger SMC package (7.11 × 6.22 mm) | Requires PCB redesign due to footprint mismatch; clamps at higher voltage, risking downstream IC stress | Choose only if board space allows SMC and system can tolerate 53.3 V clamping during 24 V load dump |
Compared with SMAJ30A and 1.5SMC33A, SM4T30AY delivers tighter VBR tolerance (±5%), lower clamping voltage (42.1 V vs. ≥48.4 V), and guaranteed AEC-Q101 qualification-making it the sole choice for production automotive ECUs requiring zero field returns under thermal and surge stress.
Availability
SM4T30AY is available at Aetrix Electronics and suitable for automotive body control modules, infotainment power supplies, ADAS camera interfaces, and electric power steering systems requiring stable component supply across extended temperature and surge conditions.
Supply support for SM4T30AY 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 specializing in automotive, industrial, and power management solutions, with broad analog, power, and protection device portfolios.
The SM4TxxAY series belongs to ST's automotive-qualified TVS diode product line, engineered specifically for ISO 7637-2 and ISO 10605 compliance in harsh-temperature vehicle subsystems.
FAQ
What is the maximum clamping voltage of SM4T30AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 42.1 V at 9.5 A for a 10/1000 µs waveform, measured at Tamb = 25 °C. This value increases with junction temperature per the αT coefficient (9.7 × 10−4/°C), reaching ~45.2 V at Tj = 125 °C using the published thermal correction formula.
Is SM4T30AY bidirectional or unidirectional?
SM4T30AY is a unidirectional TVS diode, intended for DC-biased lines such as 24 V battery feeds. Its cathode connects to the protected line and anode to ground. The "CAY" suffix (e.g., SM4T30CAY) denotes the bidirectional variant; SM4T30AY is strictly unidirectional.
Does SM4T30AY meet AEC-Q101 requirements?
Yes-SM4T30AY is fully AEC-Q101 qualified, having passed stress tests including high-temperature operating life (HTOL), temperature cycling, and ESD robustness per the AEC-Q101-001 standard. Qualification data is documented in ST's official AEC-Q101 report for the SM4TY series.
Can SM4T30AY be used in 12 V automotive systems?
Yes-it is rated for 24 V nominal systems but functions safely in 12 V applications. With VBR = 28.9–31.9 V, it provides ample margin above 13.5 V battery voltage while still clamping below 45 V during ISO 7637-2 Pulse 2a (+112 V) and Pulse 3b (+150 V) events.
SM4T30AY 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):
- 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)
SM4T30AY FAQ
1.How can I place an order for SM4T30AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T30AY 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 SM4T30AY reliable?
The price and inventory of SM4T30AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T30AY is usually 5 days.
3.What payment methods are accepted for SM4T30AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T30AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T30AY?
SM4T30AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T30AY 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 SM4T30AY?
For technical support, including SM4T30AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T30AY requirements.
6.How does Aetrix verify that SM4T30AY is sourced from the original manufacturer or authorized distributors?
All SM4T30AY 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 SM4T30AY meets industry standards.
7.What is the process for return or replacement of SM4T30AY?
All SM4T30AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T30AY, 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 SM4T30AY part is unused and in its original packaging.
Return procedure for SM4T30AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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