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STMicroelectronics SM30T42AY
- Part No.:
- SM30T42AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM30T42AY.pdf
- Description:
- TVS DIODE 36VWM 58.1VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:3,752
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Product details
Overview
SM30T42AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMC package, designed to clamp transient overvoltages up to 58.1 V (10/1000 µs) while delivering 3000 W peak pulse power and withstanding ±30 kV ESD per ISO 10605 (150 pF/330 Ω). It features 0.2 µA max leakage at 25 °C, 42.1 V nominal breakdown voltage, and operates up to 175 °C junction temperature - deployed in 12 V automotive power line protection against ISO 7637-2 pulses and load dump events.
For engineers reviewing the SM30T42AY datasheet, SM30T42AY pinout, SM30T42AY application, or SM30T42AY equivalent, this device is selected for high-reliability 12 V battery rail surge suppression where low leakage, high Tj capability, and validated ISO 10605/7637-2 compliance are mandatory design requirements.
Technical Context
The SM30T42AY uses planar silicon avalanche technology to achieve precise breakdown voltage control (40–44.2 V range), low dynamic resistance (63.2 mΩ), and stable clamping performance across temperature (αT = 10×10−4/°C). Its unidirectional configuration enables asymmetric protection of positive-going transients on DC supply lines without reverse conduction path.
It meets stringent automotive transient immunity standards: ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), Pulse 3b (+150 V), and exceeds IEC 61000-4-4 Level 4 (4 kV) and ISO 10605 Level 4 (±30 kV air/contact discharge). Thermal design leverages JEDEC-registered SMC footprint with verified Rth(j-a) dependence on copper area.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Breakdown Voltage (VBR) | 42.1 V min / 44.2 V max at 1 mA - defines precise clamping onset threshold for 12 V system overvoltage detection. |
| Clamping Voltage (VCL) | 58.1 V max at 48.4 A (10/1000 µs) - ensures downstream ICs see ≤58.1 V during worst-case surge, preserving 40 V-rated components. |
| Peak Pulse Power (PPP) | 3000 W at Tj = 25 °C - sustains 10/1000 µs surges without thermal runaway in automotive ambient conditions. |
| Leakage Current (IR) | 0.2 µA max at VRM = 36 V and 25 °C - minimizes standby power loss in always-on vehicle modules. |
| Junction Temperature (Tj) | −55 °C to +175 °C operating range - supports under-hood placement near engines and ECUs without derating. |
| ESD Withstand | ±30 kV contact & air discharge (ISO 10605, 150 pF/330 Ω) - exceeds automotive OEM ESD immunity requirements for exposed connectors. |
| Dynamic Resistance (RD) | 63.2 mΩ - determines VCL rise slope (ΔV = RD × IPP) and enables accurate clamping prediction under varying surge currents. |
Pinout & Package
SM30T42AY is housed in a JEDEC-registered SMC (DO-214AB) surface-mount package with matte tin-plated leads, optimized for high-current surge handling and automated assembly. The package measures 5.55–6.25 mm × 7.75–8.15 mm × 2.45 mm max height and supports IPC-7531-compliant footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Low-side reference terminal | Connected to ground or low-potential node; establishes unidirectional conduction path for positive transients only. |
| Cathode (K) | High-side surge input terminal | Connected to protected line (e.g., battery rail); avalanche breakdown occurs between K and A when VK-A > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability including temperature cycling, humidity bias, and mechanical shock testing. |
| Low leakage current | 0.2 µA max at 36 V and 25 °C - reduces quiescent current drain in always-on systems like body controllers and telematics. |
| High junction temperature rating | 175 °C continuous operation - enables placement in high-ambient zones (e.g., engine bay, power distribution units) without thermal derating. |
| ISO 7637-2 compliance | Validated response to Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) - covers all major automotive supply-line transients. |
| JEDEC SMC package | Standardized outline with 0.25 g mass and tape-and-reel delivery (2500 pcs/reel) - ensures compatibility with high-speed SMT lines and reflow profiles. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) Battery Rail |
|---|---|
|
Use Scenario: Protects microcontroller power supply from load dump spikes and alternator-induced surges in gasoline/diesel engine compartments. IC Role / Device Role / Timing Role: Unidirectional TVS placed between 12 V battery feed and LDO input, clamping transients within 1 ns response time. Use Value: Prevents latch-up or permanent damage to 5 V/3.3 V regulators and MCU cores during ISO 7637-2 Pulse 5b (load dump) events up to 87 V. |
Use Scenario: Shields BCM power inputs from jump-start surges, relay coil flyback, and ESD coupling through door harnesses. IC Role / Device Role / Timing Role: Primary overvoltage clamp on main 12 V input, positioned upstream of DC-DC converters and CAN transceivers. Use Value: Maintains system uptime by limiting voltage to ≤58.1 V during ±30 kV ESD events and −220 V ISO Pulse 3a, avoiding brownout resets. |
| Infotainment Head Unit Power Supply | ADAS Camera Module Power Line |
|
Use Scenario: Secures infotainment SoC power rails against ignition noise, alternator ripple, and hot-swap transients during vehicle startup/shutdown. IC Role / Device Role / Timing Role: First-stage transient suppressor before buck converter, absorbing energy before it reaches sensitive analog/digital circuitry. Use Value: Enables clean 5 V/1.8 V domain generation by suppressing ≥3000 W surges without forward voltage drop degradation over lifetime. |
Use Scenario: Protects 12 V input of rear-view or surround-view camera modules mounted externally, exposed to ESD and cable discharge. IC Role / Device Role / Timing Role: Low-leakage TVS integrated into compact camera PCB layout, minimizing parasitic capacitance (<100 pF) to avoid signal integrity impact. Use Value: Guarantees uninterrupted video streaming by surviving repeated ±30 kV air/contact discharges without parameter shift or failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ43A | 43 V VBR, 49.9 V VCL @ 43.3 A, 400 W PPP, SMA package | Lower power rating and smaller package limit use to low-energy nodes (e.g., sensor interfaces), not main battery rail. | Select when space-constrained layouts require SMA footprint and surge energy is <500 W. |
| Vishay SMA6J43A | 43 V VBR, 69.4 V VCL @ 43.2 A, 600 W PPP, SMA package | Higher clamping voltage and lower power rating reduce margin for 12 V systems facing ISO 7637-2 Pulse 1/3a. | Prefer for cost-sensitive non-critical subsystems where 69.4 V clamping is acceptable and peak current <45 A. |
Compared with SMAJ43A and SMA6J43A, SM30T42AY delivers 5× higher peak power (3000 W vs. ≤600 W), 12.5% lower clamping voltage (58.1 V vs. ≥69.4 V), and AEC-Q101 validation - making it the only suitable choice for primary 12 V rail protection in safety-critical automotive ECUs and ADAS modules.
Availability
SM30T42AY is available at Aetrix Electronics and suitable for engine control units, body control modules, infotainment head units, and ADAS camera modules requiring stable component supply across automotive production lifecycles.
Supply support for SM30T42AY 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 SM30Txx series belongs to ST's automotive-grade transient voltage suppression portfolio, engineered specifically for robust, long-life protection of 12 V and 24 V vehicle electrical systems against ISO 7637-2, ISO 10605, and IEC 61000-4-4 threats.
FAQ
What is the maximum clamping voltage of SM30T42AY under a 10/1000 µs surge?
The maximum clamping voltage is 58.1 V at 48.4 A for a 10/1000 µs waveform, measured at Tj = 25 °C. This value increases with junction temperature per αT = 10×10−4/°C, reaching ~61.2 V at 125 °C using the formula VCL(Tj) = VCL(25°C) × [1 + αT × (Tj − 25)].
Is SM30T42AY suitable for 24 V commercial vehicle applications?
No - SM30T42AY is rated for 42.1 V breakdown and 58.1 V clamping, optimized for 12 V nominal automotive systems. For 24 V applications, ST recommends SM30T82AY (82 V VBR, 113 V VCL) or SM30T100AY (100 V VBR, 137 V VCL), which provide appropriate voltage margins above 24 V rail transients.
Does SM30T42AY have bidirectional variants?
Yes - the bidirectional counterpart is SM30T42CAY, which provides symmetrical clamping for AC-coupled or floating signal lines. It shares identical VBR, VCL, and surge ratings but conducts in both directions, making it unsuitable for DC power rail protection where unidirectional blocking is required.
What is the recommended PCB footprint for SM30T42AY?
The JEDEC-registered SMC footprint requires pad dimensions of 5.11 mm × 1.54 mm per terminal, 8.19 mm center-to-center spacing, and 3.14 mm overall width. Copper area under each lead should be ≥2 cm² to maintain Rth(j-a) ≤ 40 °C/W and sustain full 3000 W pulse capability per datasheet Figure 12.
SM30T42AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AB, SMC
- Series:
- SM30TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 36V
- Voltage - Breakdown (Min):
- 40V
- Voltage - Clamping (Max) @ Ipp:
- 58.1V
- Current - Peak Pulse (10/1000µs):
- 48.4A
- Power - Peak Pulse:
- 3000W (3kW)
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMC
SM30T42AY FAQ
1.How can I place an order for SM30T42AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM30T42AY 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 SM30T42AY reliable?
The price and inventory of SM30T42AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T42AY is usually 5 days.
3.What payment methods are accepted for SM30T42AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T42AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM30T42AY?
SM30T42AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM30T42AY 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 SM30T42AY?
For technical support, including SM30T42AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T42AY requirements.
6.How does Aetrix verify that SM30T42AY is sourced from the original manufacturer or authorized distributors?
All SM30T42AY 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 SM30T42AY meets industry standards.
7.What is the process for return or replacement of SM30T42AY?
All SM30T42AY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T42AY, 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 SM30T42AY part is unused and in its original packaging.
Return procedure for SM30T42AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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