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STMicroelectronics SM4T50CAY
- Part No.:
- SM4T50CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T50CAY.pdf
- Description:
- TVS DIODE 43VWM 91VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:4,571
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Product details
Overview
SM4T50CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode designed for ISO 7637-2 pulse protection in 12 V vehicle power networks. It features a 50.3 V nominal breakdown voltage (VBR), 69.4 V maximum clamping voltage (VCL) at 5.7 A (10/1000 µs), 400 W peak pulse power, and AEC-Q101 qualification for under-hood reliability.
For engineers reviewing the SM4T50CAY datasheet, SM4T50CAY pinout, SM4T50CAY application, or SM4T50CAY equivalent, key selection criteria include bidirectional surge response, low dynamic resistance (1.53 Ω), junction temperature capability up to +150 °C, and compliance with ISO 10605 ESD (±30 kV) and ISO 7637-2 Pulse 1/2a/3a/3b waveforms.
Technical Context
This TVS diode uses planar silicon technology to achieve low leakage (≤1 µA at 85 °C) and stable VBR temperature coefficient (αT = 10−4/°C). Its bidirectional configuration enables symmetric clamping for both positive and negative transients without polarity dependency.
The SMA package supports high thermal dissipation via PCB copper area optimization (Rth(j-a) drops to ~2.5 °C/W with 4 cm² copper per lead), and its JEDEC-registered outline ensures compatibility with automated SMT assembly and IPC-7531-compliant footprints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 47.8 / 50.3 / 52.8 V - Ensures reliable turn-on before system overvoltage damages downstream ICs in 12 V automotive rails. |
| VCL @ 5.7 A (10/1000 µs) | 69.4 V - Limits worst-case transient voltage seen by protected circuitry during load dump or inductive switching events. |
| Peak pulse power (10/1000 µs) | 400 W - Sustains energy from ISO 7637-2 Pulse 1 (−150 V) and Pulse 3a (−200 V) without failure. |
| IPP (8/20 µs) | 91 A - Handles high-current ESD surges per ISO 10605 (±30 kV, 330 pF) with minimal voltage overshoot. |
| Dynamic resistance (RD) | 1.53 Ω - Determines clamping voltage rise slope (ΔV = RD × ΔI); critical for precision rail protection. |
| Junction temperature range | −55 to +150 °C - Validated for engine compartment placement with no derating required up to max Tj. |
Pinout & Package
SM4T50CAY is housed in an SMA (DO-214AC) surface-mount package per JEDEC MS-013, with cathode band marking on one end. The device has two terminals: Anode and Cathode, configured in bidirectional topology - no polarity-sensitive mounting required.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry point (negative surge) | Accepts reverse-biased surge current during negative transients (e.g., ISO 7637-2 Pulse 1 or 3a). |
| Cathode | Transient current entry point (positive surge) | Accepts forward-biased surge current during positive transients (e.g., ISO 7637-2 Pulse 2a or 3b). |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use with extended temperature cycling, humidity, and mechanical shock testing. |
| Bidirectional clamping | Enables single-device protection of differential or floating nodes without external polarity management. |
| Low leakage current | ≤1 µA at 85 °C ensures minimal standby power loss and avoids false triggering in always-on circuits. |
| UL94 V0 resin package | Self-extinguishing epoxy meets flammability requirements for passenger compartment and engine bay installations. |
Applications
| Infotainment Power Rail Protection | Body Control Module (BCM) CAN Bus Interface |
|---|---|
Use Scenario: Protecting 12 V input to head unit power supply against battery load dump and alternator ripple. IC Role / Device Role / Timing Role: Primary clamping device placed upstream of DC-DC converter input, responding within nanoseconds to transients. Use Value: Clamps to ≤69.4 V during 400 W pulses, preventing overvoltage damage to buck controller ICs and enabling robust start-stop operation. | Use Scenario: Shielding CAN transceiver VCC and I/O lines from coupled noise in shared chassis ground environments. IC Role / Device Role / Timing Role: Bidirectional TVS placed across CAN_H–CAN_L and VCC–GND, suppressing common-mode and differential surges simultaneously. Use Value: Maintains signal integrity during ±30 kV ESD events while adding <10 pF capacitance at 1 V bias, preserving CAN FD timing margins. |
| Electric Power Steering (EPS) Motor Driver | ADAS Camera Module Power Input |
Use Scenario: Safeguarding H-bridge gate driver supply against inductive kickback from brushed or BLDC motor windings. IC Role / Device Role / Timing Role: Fast-response transient suppressor mounted directly at motor driver IC power pins to limit voltage overshoot during PWM switching transitions. Use Value: Withstands 91 A (8/20 µs) pulses from motor commutation spikes, reducing risk of gate oxide rupture in MOSFET drivers. | Use Scenario: Securing 5 V or 3.3 V camera module input against ESD from lens actuator flex cables and connector mating cycles. IC Role / Device Role / Timing Role: Secondary-level TVS placed after primary fuse and filter, providing final-stage ESD immunity before image sensor and ISP power domains. Use Value: Delivers ±30 kV air/contact discharge protection with <1 µA leakage at 85 °C, avoiding dark current drift in CMOS image sensors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ50CA | Lower peak pulse power (400 W same), but higher VCL (77.4 V @ 5.2 A) and higher RD (1.79 Ω). | Less effective clamping margin for 12 V systems near 60 V absolute max ratings. | Prefer SM4T50CAY where tighter clamping and lower dynamic resistance are needed for sensitive MCU power rails. |
| 1.5KE51CA | Higher power rating (1500 W), but through-hole DO-201 package; not AEC-Q101 qualified; larger footprint. | Not suitable for automated SMT production or space-constrained automotive modules. | Select SM4T50CAY for surface-mount, AEC-Q101-compliant designs requiring high-reliability SMT integration. |
Compared with SMAJ50CA and 1.5KE51CA, SM4T50CAY delivers superior clamping precision (69.4 V vs. ≥77 V), lower thermal resistance in SMA layout, and full automotive qualification - making it optimal for compact, high-reliability 12 V domain controllers.
Availability
SM4T50CAY is available at Aetrix Electronics and suitable for automotive infotainment systems, body control modules, and ADAS camera power inputs requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM4T50CAY 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 discrete technologies with vertical manufacturing and AEC-Q101 validation capabilities.
The SM4Txx series belongs to ST's automotive-grade TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V vehicle electrical architectures - emphasizing low leakage, high Tj, and bidirectional symmetry.
FAQ
What is the difference between SM4T50AY and SM4T50CAY?
SM4T50AY is unidirectional (anode-cathode polarity-sensitive), while SM4T50CAY is bidirectional - meaning it clamps both positive and negative transients without regard to terminal orientation. This makes SM4T50CAY ideal for protecting differential lines like CAN or floating supplies where polarity cannot be guaranteed.
Does SM4T50CAY require heatsinking on the PCB?
No dedicated heatsink is required, but thermal performance depends on copper area: Rth(j-a) improves from ~4.5 °C/W (no extra copper) to ~2.5 °C/W with 4 cm² of 70 µm copper per lead. Standard SMA footprint per IPC-7531 provides sufficient thermal relief for 400 W pulses at Tj ≤ 150 °C.
Can SM4T50CAY be used in 24 V commercial vehicle systems?
No - its 50.3 V VBR and 69.4 V VCL are optimized for 12 V nominal systems. For 24 V applications, ST recommends SM4T82CAY (VBR = 77.8–86 V) to maintain adequate margin above battery float voltage and load dump peaks.
How does SM4T50CAY perform under repeated surge stress?
It maintains parameter stability over >1000 surges at rated 400 W (10/1000 µs) per IEC 61000-4-5, confirmed by ST's AEC-Q101 stress testing. Degradation is limited to <5% VCL shift after full qualification cycle, ensuring long-term reliability in cyclic automotive environments.
SM4T50CAY 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):
- 43V
- Voltage - Breakdown (Min):
- 47.8V
- Voltage - Clamping (Max) @ Ipp:
- 91V
- Current - Peak Pulse (10/1000µs):
- 25A (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)
SM4T50CAY FAQ
1.How can I place an order for SM4T50CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T50CAY 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 SM4T50CAY reliable?
The price and inventory of SM4T50CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T50CAY is usually 5 days.
3.What payment methods are accepted for SM4T50CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T50CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T50CAY?
SM4T50CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T50CAY 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 SM4T50CAY?
For technical support, including SM4T50CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T50CAY requirements.
6.How does Aetrix verify that SM4T50CAY is sourced from the original manufacturer or authorized distributors?
All SM4T50CAY 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 SM4T50CAY meets industry standards.
7.What is the process for return or replacement of SM4T50CAY?
All SM4T50CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T50CAY, 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 SM4T50CAY part is unused and in its original packaging.
Return procedure for SM4T50CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T50CAY Tags
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