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STMicroelectronics SM6T68AY
- Part No.:
- SM6T68AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SM6T68AY.pdf
- Description:
- TVS DIODE 58.1VWM 92VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:2,477
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Product details
Overview
SM6T68AY from STMicroelectronics is an AEC-Q101-qualified unidirectional transient voltage suppression (TVS) diode in SMB package, designed for automotive circuit protection against ISO 7637-2 pulses (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −220 V; Pulse 3b: +150 V) and ESD per ISO 10605 (±30 kV air/contact discharge). It features a 68 V standoff voltage (VRM), 92 V clamping voltage at 6.5 A (10/1000 µs), 600 W peak pulse power, and operates up to 150 °C junction temperature.
For engineers reviewing the SM6T68AY datasheet, SM6T68AY pinout, SM6T68AY application, or SM6T68AY equivalent, this device is selected for high-reliability 12 V/24 V automotive power line protection where low leakage (<0.2 µA at 25 °C), stable clamping under thermal stress, and compliance with IEC 61000-4-4 Level 4 (4 kV) are critical design requirements.
Technical Context
The SM6T68AY uses planar silicon junction technology to achieve low dynamic resistance (1.503 Ω) and stable breakdown voltage drift coefficient (αT = 10.4 × 10⁻⁴ /°C), enabling predictable clamping performance across −55 °C to +150 °C operating range. Its unidirectional polarity supports DC-biased lines such as battery feeds and ECU power rails.
It meets ISO 7637-2 surge immunity without external series impedance for Pulse 1, 2a, and 3b, and delivers 121 A peak pulse current (8/20 µs) with 33 Ω dynamic resistance - optimized for fast energy diversion before downstream IC damage occurs in CAN, LIN, or sensor supply paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 68 V - Maximum continuous reverse operating voltage before significant leakage; defines minimum system operating margin above nominal 12 V/24 V rail. |
| Breakdown Voltage (VBR) | 58.1–71.4 V @ IBR = 1 mA - Tight tolerance ensures consistent turn-on threshold across production lots and temperature. |
| Clamping Voltage (VCL) | 92 V @ IPP = 6.5 A (10/1000 µs) - Limits transient voltage seen by protected ICs; enables safe operation of 75 V-rated regulators or microcontrollers. |
| Peak Pulse Power (PPP) | 600 W @ 10/1000 µs - Sustains high-energy transients typical of load dump or inductive switching in automotive environments. |
| Leakage Current (IRM) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Minimizes standby power loss and avoids false triggering in low-current sensor circuits. |
| Junction Temperature Range | −55 °C to +150 °C - Supports under-hood placement near engines or power modules without derating. |
| Dynamic Resistance (RD) | 1.503 Ω - Low impedance during clamping reduces voltage overshoot and improves energy absorption linearity. |
Pinout & Package
SM6T68AY is housed in an SMB (DO-214AA) surface-mount package with two terminals: Cathode (marked end) and Anode. The package complies with JEDEC registered outline, IPC7531 footprint, and features matte tin-plated leads rated for 260 °C soldering (10 s).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked end) | Transient current sink | Connected to protected line; conducts surge current to ground when voltage exceeds VRM; polarity must match DC bias direction. |
| Anode | Reference node | Typically tied to system ground or low-impedance return path; forms the reverse-biased junction that triggers clamping. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability including temperature cycling, humidity testing, and mechanical shock - required for engine control, ADAS, and body electronics. |
| Low dynamic resistance (1.503 Ω) | Reduces clamping voltage rise under high-current surges, improving protection margin for 5 V/3.3 V logic supplies downstream. |
| High-temperature operation (Tj max = 150 °C) | Enables direct placement on high-power PCB traces near motors or DC-DC converters without thermal derating penalties. |
| ESD robustness (±30 kV contact/air) | Exceeds ISO 10605 Level 4 - eliminates need for secondary ESD protection on exposed connectors or sensors. |
| Planar junction construction | Delivers stable leakage and breakdown characteristics over lifetime, critical for long-service-life automotive modules (>15 years). |
Applications
| Engine Control Unit (ECU) Power Input | Automotive CAN Transceiver Protection |
|---|---|
|
Use Scenario: Protects 12 V input rail of engine control units against load dump (ISO 7637-2 Pulse 5a) and alternator-induced transients. IC Role / Device Role / Timing Role: Primary clamping device placed directly at connector entry point before DC-DC converter input. Use Value: Clamps 92 V at 6.5 A (10/1000 µs), limiting stress on 75 V-rated input capacitors and preventing regulator latch-up. |
Use Scenario: Shields high-speed CAN FD transceivers (e.g., TJA1044) from ESD events on bus lines during vehicle assembly or service. IC Role / Device Role / Timing Role: Unidirectional TVS on CAN_H and CAN_L lines referenced to ground, with fast response (<1 ns) to ±30 kV discharges. Use Value: Maintains <0.2 µA leakage at 25 °C, avoiding signal distortion or common-mode offset in differential bus operation. |
| Body Control Module (BCM) Sensor Supply | Automotive Lighting Driver Input |
|
Use Scenario: Guards 5 V/12 V sensor supply rails (e.g., for ambient temperature or rain sensors) against battery reversal and jump-start spikes. IC Role / Device Role / Timing Role: Standoff-rated TVS on regulated output of LDOs feeding analog front-ends. Use Value: 68 V VRM provides 5× margin over 12 V nominal rail, ensuring no conduction during normal operation while responding to −150 V ISO Pulse 1. |
Use Scenario: Protects LED driver IC inputs (e.g., STLED316) from transients induced by PWM dimming or relay switching in headlamp modules. IC Role / Device Role / Timing Role: Front-end surge suppressor on HV input stage prior to buck controller. Use Value: 600 W peak power rating handles repetitive 8/20 µs surges from inductive ballast switching without degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ68A | Same 68 V VRM, but lower PPP = 400 W (10/1000 µs); higher VCL = 110 V @ 5.5 A; SMB package. | Limited to non-load-dump scenarios; insufficient for ISO 7637-2 Pulse 5a (load dump) in 12 V systems. | Select only if thermal budget restricts PCB copper area and peak surge energy is ≤400 W. |
| 1.5SMC68A | Higher PPP = 1500 W (10/1000 µs), but larger SMC package (7.11 × 6.22 mm); VCL = 112 V @ 13.3 A. | Requires more board space; better suited for heavy-duty commercial vehicle applications with higher surge exposure. | Choose when system-level testing confirms >1 kW surge capability is needed and SMB footprint is not constrained. |
Compared with SMAJ68A and 1.5SMC68A, SM6T68AY uniquely balances AEC-Q101 compliance, SMB footprint, 600 W capability, and 92 V clamping - making it optimal for space-constrained automotive ECUs requiring certified, production-ready surge immunity.
Availability
SM6T68AY is available at Aetrix Electronics and suitable for automotive engine control units, CAN bus interfaces, body control modules, and LED lighting drivers requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM6T68AY 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 rigorous quality certification.
The SM6TY series is part of ST's automotive-grade Transil™ TVS portfolio, engineered specifically for ISO 7637-2 and ISO 10605 compliance in harsh-temperature vehicle subsystems - prioritizing reliability over cost in safety-critical power and data lines.
FAQ
What is the maximum clamping voltage of SM6T68AY under a 10/1000 µs surge?
The maximum clamping voltage (VCL) of SM6T68AY is 92 V at 6.5 A for a 10/1000 µs waveform, measured at Tamb = 25 °C. This value increases with junction temperature at a rate defined by αT = 10.4 × 10⁻⁴ /°C, reaching approximately 98 V at Tj = 125 °C per datasheet calculation.
Is SM6T68AY suitable for protecting a 24 V automotive system?
Yes - its 68 V standoff voltage provides 2.8× margin above nominal 24 V systems, and it is explicitly validated for ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V), all of which exceed worst-case transients in 24 V commercial vehicle applications.
How does SM6T68AY differ from bidirectional SM6T68CAY?
SM6T68AY is unidirectional and intended for DC-biased lines (e.g., power rails), conducting only in reverse breakdown. SM6T68CAY is bidirectional, symmetrically clamping both polarities - used for AC-coupled or floating signals like antenna lines or differential buses where polarity reversal may occur.
Does SM6T68AY require a heatsink for 600 W surge dissipation?
No - the 600 W rating is for a single 10/1000 µs pulse with junction-to-ambient thermal impedance of ~35 °C/W on recommended FR4 footprint (2.18 cm² copper per lead). Continuous power handling is limited to ~1.5 W; heatsinking is unnecessary for transient-only duty cycles typical in automotive surge protection.
SM6T68AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SM6TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 58.1V
- Voltage - Breakdown (Min):
- 64.6V
- Voltage - Clamping (Max) @ Ipp:
- 92V
- Current - Peak Pulse (10/1000µs):
- 6.5A
- Power - Peak Pulse:
- 600W
- 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:
- SMB
SM6T68AY FAQ
1.How can I place an order for SM6T68AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM6T68AY 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 SM6T68AY reliable?
The price and inventory of SM6T68AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM6T68AY is usually 5 days.
3.What payment methods are accepted for SM6T68AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM6T68AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM6T68AY?
SM6T68AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM6T68AY 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 SM6T68AY?
For technical support, including SM6T68AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM6T68AY requirements.
6.How does Aetrix verify that SM6T68AY is sourced from the original manufacturer or authorized distributors?
All SM6T68AY 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 SM6T68AY meets industry standards.
7.What is the process for return or replacement of SM6T68AY?
All SM6T68AY units undergo pre-shipment inspection (PSI). If there is an issue with SM6T68AY, 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 SM6T68AY part is unused and in its original packaging.
Return procedure for SM6T68AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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