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STMicroelectronics SM4T56CAY
- Part No.:
- SM4T56CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T56CAY.pdf
- Description:
- TVS DIODE 48VWM 100VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:14,883
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Product details
Overview
SM4T56CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppressor (TVS) diode designed for ISO 7637-2 pulse protection in 12 V vehicle power systems. It delivers 400 W peak pulse power (10/1000 µs), clamps at 77.4 V (max) under 5.2 A surge, and operates up to 150 °C junction temperature - deployed across engine control units, body electronics, and infotainment power rails.
For engineers reviewing the SM4T56CAY datasheet, SM4T56CAY pinout, SM4T56CAY application, or SM4T56CAY equivalent, key selection criteria include bidirectional clamping behavior, 56 V nominal breakdown voltage, low dynamic resistance (1.79 Ω), AEC-Q101 qualification, and SMA package compatibility with IPC 7531 footprints.
Technical Context
This TVS uses planar silicon technology to achieve low leakage (≤1 µA at 85 °C) and stable VBR drift (αT = 10−4/°C), enabling long-term reliability in high-temperature automotive environments. Its bidirectional structure provides symmetrical clamping for both positive and negative transients without polarity dependency.
It meets ISO 10605 ESD immunity (±30 kV air/contact) and full ISO 7637-2 surge compliance - including Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−200 V), and Pulse 3b (+150 V) - with clamping voltage defined per IEC 61000-4-5 test waveforms.
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 battery systems |
| VCL @ 5.2 A (10/1000 µs) | 77.4 V - maximum clamped voltage during standard automotive surge events |
| RD (dynamic resistance) | 1.79 Ω - determines voltage overshoot under fast-rising transients; lower value improves clamping precision |
| IPP (8/20 µs) | 100 A - peak current handling capability for high-energy lightning-induced surges |
| IR (leakage @ 85 °C) | 1 µA - minimal standby power loss and signal integrity impact in always-on circuits |
| Tjmax | 150 °C - supports placement near heat-generating components like power MOSFETs or DC-DC converters |
| AEC-Q101 qualified | Validated for automotive underhood use per stress testing including temperature cycling, HTRB, and HTGB |
Pinout & Package
SM4T56CAY is housed in an industry-standard SMA (DO-214AC) surface-mount package per JEDEC MS-013, with dual cathode-anode terminals on a single planar die. The package features UL94 V-0 rated epoxy resin and complies with IPC 7531 footprint recommendations.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Surge current entry (negative transients) | Connects to protected line; conducts during reverse-polarity surges in bidirectional operation |
| Cathode | Surge current entry (positive transients) | Connects to protected line; conducts during positive-voltage surges in bidirectional operation |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating lines without polarity constraints |
| Low dynamic resistance (1.79 Ω) | Reduces clamping voltage rise under high di/dt, improving protection margin for 5 V/3.3 V logic |
| AEC-Q101 qualification | Confirms suitability for automotive safety-critical modules including ADAS sensors and gateway ECUs |
| 150 °C operating junction temperature | Supports mounting in high-ambient zones such as under-hood power distribution units |
| UL94 V-0 resin encapsulation | Meets flammability requirements for passenger compartment and battery management system assemblies |
Applications
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|---|---|
|
Use Scenario: Protecting LIN bus transceivers and sensor supply rails from load dump and alternator ripple. IC Role / Device Role / Timing Role: Bidirectional TVS placed between 12 V rail and ground, clamping transients before they reach LDOs and microcontrollers. Use Value: Prevents latch-up or permanent damage to 3.3 V MCU I/O during ISO 7637-2 Pulse 2a (+112 V) events. |
Use Scenario: Safeguarding door module power inputs against ESD and battery reversal during service. IC Role / Device Role / Timing Role: Primary surge clamp on fused 12 V input, positioned upstream of power switches and CAN transceivers. Use Value: Maintains <1 µA leakage at 85 °C to avoid draining standby current in sleep-mode vehicle states. |
| Infotainment Head Unit | ADAS Camera Power Input |
|
Use Scenario: Shielding USB-C and HDMI power lines from hot-plug transients and ESD in center console interfaces. IC Role / Device Role / Timing Role: Secondary-level TVS after primary fuse, targeting fast 8/20 µs surges from cable coupling. Use Value: Clamps to ≤77.4 V within 1 ns, preserving voltage tolerance margins of USB PD controllers. |
Use Scenario: Protecting 12 V camera power feed from ignition noise and jump-start spikes in rear-view systems. IC Role / Device Role / Timing Role: First-line defense on camera module PCB, mounted adjacent to connector entry point. Use Value: Withstands −200 V ISO 7637-2 Pulse 3a without degradation, ensuring functional safety compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ58A | Unidirectional; 58 V VBR; 400 W rating; higher IR (5 µA @ 85 °C) | Requires external polarity management; unsuitable for AC-coupled or floating lines | Select only when circuit polarity is fixed and leakage budget allows ≥5× increase |
| TPSMD58CA | Bidirectional; 58 V VBR; 600 W rating; larger SMC package; higher thermal mass | Occupies more PCB area; better for sustained surge duty but less space-efficient | Prefer when board layout permits SMC footprint and higher energy absorption is required |
Compared with SMAJ58A and TPSMD58CA, SM4T56CAY offers tighter VBR tolerance (±5%), lower leakage, and optimized SMA footprint for dense automotive PCBs - making it preferred for space-constrained, always-on modules requiring precise clamping and AEC-Q101 traceability.
Availability
SM4T56CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, infotainment head units, and ADAS camera power inputs requiring stable component supply across automotive production lifecycles.
Supply support for SM4T56CAY 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 capabilities.
SM4T56CAY belongs to the SM4TY series - a family of AEC-Q101-qualified TVS diodes engineered specifically for robust ISO 7637-2 and ISO 10605 protection in 12 V automotive electrical architectures.
FAQ
What does the 'CAY' suffix indicate in SM4T56CAY?
The 'C' denotes bidirectional configuration, 'A' indicates automotive grade, and 'Y' specifies the SMA (DO-214AC) package. This distinguishes it from unidirectional 'AY' variants and confirms AEC-Q101 qualification and UL94 V-0 resin compliance per STMicroelectronics' ordering nomenclature.
How does SM4T56CAY handle ISO 7637-2 Pulse 1 (−150 V)?
SM4T56CAY clamps Pulse 1 transients at ≤77.4 V (measured at 5.2 A, 10/1000 µs) due to its bidirectional structure and low dynamic resistance (1.79 Ω). Its 400 W rating ensures no thermal failure during this standardized −150 V load-dump event on 12 V systems.
Can SM4T56CAY replace SM4T56AY in a design?
No - SM4T56AY is unidirectional and only protects against positive transients; substituting it with bidirectional SM4T56CAY alters circuit behavior. Reverse-biased conduction may cause unintended current paths in polarized circuits, risking latch-up or regulator instability unless layout and grounding are revalidated.
What is the recommended PCB footprint for SM4T56CAY?
STMicroelectronics specifies a 5.43 mm × 1.40 mm pad layout matching IPC 7531 for SMA packages, with 1.64 mm pad spacing and 2.63 mm pad length. Thermal relief vias under each terminal are advised to maintain Rth(j-a) ≤ 120 °C/W for continuous 150 °C operation.
SM4T56CAY 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):
- 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)
SM4T56CAY FAQ
1.How can I place an order for SM4T56CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T56CAY 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 SM4T56CAY reliable?
The price and inventory of SM4T56CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T56CAY is usually 5 days.
3.What payment methods are accepted for SM4T56CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T56CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T56CAY?
SM4T56CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T56CAY 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 SM4T56CAY?
For technical support, including SM4T56CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T56CAY requirements.
6.How does Aetrix verify that SM4T56CAY is sourced from the original manufacturer or authorized distributors?
All SM4T56CAY 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 SM4T56CAY meets industry standards.
7.What is the process for return or replacement of SM4T56CAY?
All SM4T56CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T56CAY, 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 SM4T56CAY part is unused and in its original packaging.
Return procedure for SM4T56CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T56CAY Tags
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