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STMicroelectronics SM4T39CAY
- Part No.:
- SM4T39CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SM4T39CAY.pdf
- Description:
- TVS DIODE 33VWM 69.7VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:10,896
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Product details
Overview
SM4T39CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMA package, designed for ISO 7637-2 pulse protection (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −200 V; Pulse 3b: +150 V) and ISO 10605 ESD immunity (±30 kV air/contact). It features 39 V breakdown voltage (VBR = 36.7–40.5 V at IBR = 1 mA), 53.3 V clamping voltage (VCL) at 7.5 A (10/1000 µs), and 400 W peak pulse power rating. Used in 12 V automotive power line protection for ECUs and body control modules.
For engineers reviewing the SM4T39CAY datasheet, SM4T39CAY pinout, SM4T39CAY application, or SM4T39CAY equivalent, key selection criteria include bidirectional surge capability, low leakage (≤1 µA at 85 °C), AEC-Q101 qualification, junction temperature range (−55 to +150 °C), and SMA footprint compatibility with IPC 7531.
Technical Context
The SM4T39CAY implements a planar silicon junction structure optimized for high-reliability automotive environments, enabling stable operation up to Tj = 150 °C with minimal thermal drift (αT = 10 × 10−4/°C). Its bidirectional configuration provides symmetrical clamping for both positive and negative transients without polarity dependency.
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), while delivering 30 kV ESD robustness per ISO 10605 under both 150 pF/330 Ω and 330 pF/330 Ω test conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 36.7 V / 38.6 V / 40.5 V at IBR = 1 mA - defines precise reverse breakdown threshold for reliable overvoltage triggering |
| VCL @ IPP | 53.3 V at 7.5 A (10/1000 µs) - maximum clamped voltage seen by protected circuit during worst-case surge |
| PPP | 400 W (10/1000 µs) - peak power dissipation capability under standardized long-duration surge waveform |
| IR @ VRM | 0.2 µA at 25 °C, 1 µA at 85 °C - ultra-low leakage ensures minimal standby current draw in always-on vehicle systems |
| Tj operating range | −55 °C to +150 °C - supports under-hood deployment in extreme thermal environments without derating |
| Stand-off voltage VRM | 33 V - maximum continuous reverse working voltage before leakage exceeds specification |
| AEC-Q101 qualified | Qualified per AEC-Q101 Rev D - validated for automotive reliability including HTOL, TCT, and ESD stress testing |
Pinout & Package
SM4T39CAY is housed in an industry-standard SMA (DO-214AC) surface-mount package per JEDEC MS-013, with two terminals: Cathode and Anode. The bidirectional design means both terminals are functionally symmetric-no polarity marking required for mounting orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Surge return path (bidirectional) | Provides low-impedance path for negative transients; electrically identical to cathode in bidirectional TVS |
| Cathode | Surge return path (bidirectional) | Provides low-impedance path for positive transients; electrically identical to anode in bidirectional TVS |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional surge protection | Enables single-device protection of AC-coupled or floating automotive signals without polarity concerns |
| Planar junction technology | Delivers stable VBR and low leakage across full temperature range (−55 to +150 °C) |
| UL94 V0-compliant resin | Ensures flame-retardant encapsulation meeting automotive safety and regulatory requirements |
| ISO 7637-2 & ISO 10605 compliance | Validated against full suite of automotive electrical disturbance tests including Pulse 1, 2a, 3a, 3b, and ±30 kV ESD |
| SMA footprint (IPC 7531) | Enables drop-in PCB replacement with legacy SMA TVS devices and supports automated assembly |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) CAN Bus Lines |
|---|---|
|
Use Scenario: Protecting 12 V supply rail of engine control units against load dump and alternator-induced surges. IC Role / Device Role / Timing Role: Bidirectional TVS clamps both positive and negative transients on main power input before they reach downstream regulators and microcontrollers. Use Value: Prevents latch-up or permanent damage to MCU and analog front-end ICs during ISO 7637-2 Pulse 1 (−150 V) and Pulse 2a (+112 V). |
Use Scenario: Shielding differential CAN H/L lines in body control modules from ESD events and coupled transients. IC Role / Device Role / Timing Role: Placed across CAN bus pair to clamp common-mode surges while preserving signal integrity due to low dynamic resistance (RD = 0.884 Ω). Use Value: Maintains CAN FD communication integrity under ±30 kV contact discharge (ISO 10605) without data corruption or node reset. |
| Infotainment System USB Interface | ADAS Camera Power Line |
|
Use Scenario: Safeguarding USB 2.0 VBUS and data lines in automotive infotainment head units against hot-plug surges and ESD. IC Role / Device Role / Timing Role: Dual-channel placement (one device per line) suppresses fast-rising ESD pulses (IEC 61000-4-2) before reaching USB transceivers. Use Value: Achieves system-level ESD immunity without adding series impedance that degrades 480 Mbps signaling performance. |
Use Scenario: Protecting 12 V power feed to forward-facing ADAS cameras mounted behind windshield. IC Role / Device Role / Timing Role: Primary surge limiter on camera module input, absorbing ISO 7637-2 Pulse 3a (−200 V) and Pulse 3b (+150 V) induced by nearby switching loads. Use Value: Ensures uninterrupted video streaming during repeated surge events, avoiding image dropout or sensor reset in autonomous driving scenarios. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional automotive TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ39CA | Same VBR (36.7–40.5 V), but SMB package (larger footprint); 600 W PPP (10/1000 µs) | Higher surge margin but requires PCB redesign; not suitable for space-constrained modules | Select when higher peak power handling is prioritized over board area and weight |
| 1.5KE39CA | Through-hole DO-201 package; 1500 W PPP; higher VCL (67 V at 22.4 A) | Not AEC-Q101 qualified; unsuitable for production automotive use; limited thermal cycling endurance | Acceptable only for non-automotive prototyping or industrial backup designs |
Compared with SMBJ39CA and 1.5KE39CA, SM4T39CAY offers optimal balance of AEC-Q101 compliance, SMA footprint compatibility, and precise clamping (53.3 V) for modern compact automotive electronics-making it preferred for ECU, BCM, and ADAS modules where reliability, size, and thermal stability are jointly critical.
Availability
SM4T39CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, infotainment systems, and ADAS camera power supplies requiring stable component supply across automotive production lifecycles.
Supply support for SM4T39CAY 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 broad IP portfolio and vertical manufacturing capabilities.
The SM4Txx series belongs to ST's automotive-qualified TVS portfolio, engineered specifically for robust transient suppression in 12 V and 24 V vehicle electrical architectures per ISO 7637-2 and ISO 10605.
FAQ
Is SM4T39CAY unidirectional or bidirectional?
SM4T39CAY is a bidirectional TVS diode, indicated by the "C" in its part number. It provides symmetrical clamping for both positive- and negative-polarity transients without requiring polarity-specific placement on PCB, making it ideal for protecting differential buses like CAN or AC-coupled signals.
What is the maximum clamping voltage at 7.5 A (10/1000 µs)?
The maximum clamping voltage (VCL) for SM4T39CAY is 53.3 V at 7.5 A under the 10/1000 µs waveform. This value is measured at Tamb = 25 °C and defines the upper voltage limit imposed on protected circuitry during standardized surge events.
Does SM4T39CAY meet AEC-Q101 requirements?
Yes, SM4T39CAY is fully AEC-Q101 qualified per Rev D, having passed stress tests including high-temperature operating life (HTOL), temperature cycling (TCT), and human-body-model ESD (HBM ≥ 8 kV), confirming suitability for automotive under-hood and cabin applications.
Can SM4T39CAY replace SM4T39AY in a design?
No-SM4T39AY is unidirectional (anode-cathode asymmetric), while SM4T39CAY is bidirectional. Substitution requires verifying circuit topology: unidirectional devices require correct polarity orientation and cannot protect against reverse-polarity surges, unlike the bidirectional CAY version.
SM4T39CAY 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):
- 33V
- Voltage - Breakdown (Min):
- 36.7V
- Voltage - Clamping (Max) @ Ipp:
- 69.7V
- Current - Peak Pulse (10/1000µs):
- 33A (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)
SM4T39CAY FAQ
1.How can I place an order for SM4T39CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM4T39CAY 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 SM4T39CAY reliable?
The price and inventory of SM4T39CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM4T39CAY is usually 5 days.
3.What payment methods are accepted for SM4T39CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM4T39CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM4T39CAY?
SM4T39CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM4T39CAY 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 SM4T39CAY?
For technical support, including SM4T39CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM4T39CAY requirements.
6.How does Aetrix verify that SM4T39CAY is sourced from the original manufacturer or authorized distributors?
All SM4T39CAY 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 SM4T39CAY meets industry standards.
7.What is the process for return or replacement of SM4T39CAY?
All SM4T39CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM4T39CAY, 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 SM4T39CAY part is unused and in its original packaging.
Return procedure for SM4T39CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM4T39CAY Tags
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