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STMicroelectronics SM4T56AY
- Part No.:
- SM4T56AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T56AY.pdf
- Description:
- TVS DIODE 48VWM 100VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:6,618
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Product details
Overview
SM4T56AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMA package, designed to clamp transient surges up to 77.4 V (VCL) at 5.2 A (IPP) under 10/1000 µs waveform while dissipating 400 W peak pulse power. It features 56.1 V nominal breakdown voltage (VBR), 0.2 µA leakage at 25 °C, and operates up to 150 °C junction temperature - deployed in 12 V automotive power line protection against ISO 7637-2 Pulse 1 (−150 V) and ISO 10605 ESD events.
For engineers reviewing the SM4T56AY datasheet, SM4T56AY pinout, SM4T56AY application, or SM4T56AY equivalent, this device is selected for robust overvoltage immunity in engine control units, body electronics, and infotainment power rails where low leakage, high Tj stability, and JEDEC-standard SMA footprint compatibility are critical.
Technical Context
The SM4T56AY uses planar silicon junction technology to achieve stable VBR temperature coefficient (αT = 10−4/°C) and low dynamic resistance (RD = 1.79 Ω), enabling precise clamping across −55 °C to +150 °C operating range. Its unidirectional polarity supports DC-biased lines like battery feeds and sensor supplies.
It meets stringent automotive surge standards: ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V), with validated 30 kV ESD immunity per ISO 10605 (both 150 pF/330 Ω and 330 pF/330 Ω configurations).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 53.3 / 56.1 / 58.9 V - ensures reliable turn-on before downstream IC damage in 12 V systems |
| VCL @ 10/1000 µs | 77.4 V - maximum clamped voltage seen by protected circuit during 400 W surge |
| IPP @ 10/1000 µs | 5.2 A - peak current handled without degradation under standard automotive surge test |
| RD | 1.79 Ω - low dynamic resistance minimizes voltage overshoot during fast transients |
| IR @ VRM | 0.2 µA at 25 °C - ultra-low leakage preserves battery drain budget in always-on modules |
| Tj max | +150 °C - enables placement near hot components (e.g., power converters, ECUs) without derating |
| Package | SMA (JEDEC DO-214AC) - surface-mount footprint compatible with IPC-7531 layout standards |
Pinout & Package
SMA package: single-sided, two-terminal surface-mount device with cathode band marking; dimensions per JEDEC DO-214AC (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 | Reference node for unidirectional clamping | Connected to ground or low-side return path; defines polarity of surge conduction |
| Cathode | Surge input terminal | Connected to protected line (e.g., battery rail); conducts transient energy to ground when VAK > VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood and cabin environments including thermal cycling, humidity, and mechanical shock |
| ISO 7637-2 compliance | Withstands defined load-dump and switching transients (Pulse 1, 2a, 3a, 3b) without parametric shift |
| UL94 V0 resin housing | Self-extinguishing encapsulation prevents flame propagation in enclosed vehicle compartments |
| Low αT (10−4/°C) | Stable VBR across temperature - avoids false triggering or insufficient clamping at extremes |
| Planar junction construction | Enables consistent RD and low leakage vs. conventional diffused junctions, supporting long-term reliability |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) CAN Bus Supply |
|---|---|
Use Scenario: Protects 12 V supply rail feeding microcontroller, fuel injector drivers, and sensors from alternator load dump and inductive kickback. IC Role / Device Role / Timing Role: Unidirectional shunt clamping device placed upstream of DC-DC converter input. Use Value: Limits transient voltage to ≤77.4 V, preventing latch-up or gate oxide rupture in 3.3 V/5 V logic supplies derived from same rail. |
Use Scenario: Shields 5 V or 3.3 V CAN transceiver VCC supply from coupled noise on shared BCM power domain. IC Role / Device Role / Timing Role: Secondary-level TVS on local regulator output, complementing primary battery-line protection. Use Value: Maintains <0.2 µA leakage at 25 °C to avoid quiescent current violation in sleep-mode BCM designs. |
| Infotainment Head Unit Power Rail | ADAS Camera Module Power Interface |
Use Scenario: Guards main 12 V input to display processor and audio amplifier against jump-start surges and ESD from USB/HDMI connectors. IC Role / Device Role / Timing Role: First-line transient suppressor before fuse and reverse-polarity protection MOSFET. Use Value: Delivers 400 W peak power handling (10/1000 µs) without thermal runaway, verified at Tj = 150 °C. |
Use Scenario: Secures 5 V camera sensor supply against ESD from lens actuator flex cables and board-level coupling. IC Role / Device Role / Timing Role: Localized TVS adjacent to image sensor IC, minimizing trace inductance for sub-ns response. Use Value: Achieves 30 kV air/contact ESD immunity per ISO 10605, preserving pixel integrity and avoiding reset faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ58A | Higher VBR (54.2–61.2 V), lower PPP (400 W), same SMA package but non-AEC-Q101 qualified | Lacks automotive qualification; suitable only for industrial/commercial 12 V systems | Select if AEC-Q101 is not required and cost sensitivity outweighs qualification needs |
| SMBJ58A | Same VBR range, higher PPP (600 W), larger SMB package (DO-214AA), AEC-Q101 qualified | Requires PCB area increase (~30% larger footprint); better for higher-energy transients | Choose when system-level surge testing exceeds 400 W or thermal margin is constrained |
Compared with SMAJ58A and SMBJ58A, SM4T56AY uniquely balances AEC-Q101 compliance, SMA footprint constraints, and precise 56.1 V VBR targeting 12 V automotive rails - making it optimal for space-constrained ECU and ADAS modules requiring certified reliability.
Availability
SM4T56AY 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 SM4T56AY 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 broad IP portfolio.
The SM4TxxAY series belongs to ST's automotive-grade transient voltage suppression product line, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle electrical architectures.
FAQ
What is the maximum clamping voltage of SM4T56AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) is 77.4 V at 5.2 A peak pulse current (IPP) for a 10/1000 µs waveform, measured at Tamb = 25 °C. This value increases linearly with junction temperature using αT = 10−4/°C, reaching ~81.2 V at Tj = 125 °C per datasheet calculation method.
Is SM4T56AY bidirectional or unidirectional?
SM4T56AY is unidirectional: it conducts surge current only when cathode-to-anode voltage exceeds VBR, making it suitable for DC-biased lines like battery feeds and regulated supplies. The "AY" suffix denotes unidirectional configuration; "CAY" indicates bidirectional variant.
Does SM4T56AY meet AEC-Q101 requirements for solder reflow?
Yes - SM4T56AY is qualified per AEC-Q101 and supports ST's recommended lead-free reflow profile: peak temperature 240–245 °C for 60–90 seconds, ramp rates ≤3 °C/s, and cooling rate ≥−6 °C/s, compliant with IPC/JEDEC J-STD-020.
How does SM4T56AY differ from SM4T56CAY?
SM4T56AY is unidirectional with cathode-marked polarity; SM4T56CAY is bidirectional, symmetrically clamping both positive and negative transients. Their VBR, VCL, and IPP values are identical, but CAY requires no polarity-aware layout and suits AC-coupled or floating signal lines.
SM4T56AY 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):
- 48V
- Voltage - Breakdown (Min):
- 53.3V
- Voltage - Clamping (Max) @ Ipp:
- 100V
- Current - Peak Pulse (10/1000µs):
- 23A (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)
SM4T56AY FAQ
1.How can I place an order for SM4T56AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T56AY 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 SM4T56AY reliable?
The price and inventory of SM4T56AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T56AY is usually 5 days.
3.What payment methods are accepted for SM4T56AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T56AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T56AY?
SM4T56AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T56AY 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 SM4T56AY?
For technical support, including SM4T56AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T56AY requirements.
6.How does Aetrix verify that SM4T56AY is sourced from the original manufacturer or authorized distributors?
All SM4T56AY 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 SM4T56AY meets industry standards.
7.What is the process for return or replacement of SM4T56AY?
All SM4T56AY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T56AY, 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 SM4T56AY part is unused and in its original packaging.
Return procedure for SM4T56AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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