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STMicroelectronics SM50T28AY
- Part No.:
- SM50T28AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM50T28AY.pdf
- Description:
- AUTOMOTIVE 5000 W, 24 V TVS IN S
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
SM50T28AY from STMicroelectronics is an AEC-Q101-qualified unidirectional automotive TVS diode in SMC package, designed to clamp transient surges up to 5000 W (10/1000 µs) and 72.9 A peak pulse current while maintaining 38.9 V clamping voltage at 25 °C. It features 24 V stand-off voltage (VRM), 0.2 µA leakage at 25 °C, and operates up to 175 °C junction temperature-enabling robust protection of 24 V battery rail circuits against ISO 7637-2 pulses and ISO 10605 ESD events.
For engineers reviewing the SM50T28AY datasheet, SM50T28AY pinout, SM50T28AY application, or SM50T28AY equivalent, key selection criteria include clamping voltage stability across temperature, low dynamic resistance (27.0 mΩ), compliance with automotive surge standards (ISO 7637-2 Pulse 1/2a/3a/3b), and compatibility with high-reliability e-breaker and power distribution modules.
Technical Context
This unidirectional TVS diode uses planar silicon technology to achieve low leakage and high thermal robustness. Its breakdown voltage is specified at 26.7–29.5 V (min–max at 1 mA), with a temperature coefficient αT of 10⁻⁴/°C enabling predictable VBR drift over –55 °C to +175 °C operation.
The device delivers 5000 W peak pulse power under 10/1000 µs waveform and sustains 760 W at 175 °C junction temperature. Clamping behavior is defined by VCL = VBRmax + RD × IPPappli, where RD = 27.0 mΩ ensures tight voltage control during fast transients like ISO 7637-2 Pulse 3b (VS = +150 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Stand-off Voltage (VRM) | 24 V - Maximum continuous reverse operating voltage before significant conduction begins. |
| Breakdown Voltage (VBR) | 26.7–29.5 V at 1 mA - Ensures reliable triggering above system nominal voltage without false clamping. |
| Clamping Voltage (VCL) | 38.9 V at 129 A (10/1000 µs) - Limits downstream IC voltage stress during load dump or inductive switching events. |
| Peak Pulse Power (PPP) | 5000 W (10/1000 µs), 72.9 kW (8/20 µs) - Handles severe automotive transients including ISO 7637-2 Pulse 5b load dump surges. |
| Leakage Current (IRM) | 0.2 µA at VRM and 25 °C - Minimizes standby power loss in always-on vehicle networks (e.g., CAN wake-up lines). |
| Junction Temperature Range | –55 °C to +175 °C - Supports under-hood placement near engine control units and battery management systems. |
| Dynamic Resistance (RD) | 27.0 mΩ - Low impedance enables rapid voltage clamping and reduces energy dissipation in protected circuitry. |
Pinout & Package
SM50T28AY is housed in a JEDEC-registered SMC (DO-214AB) surface-mount package with matte tin-plated leads. The package measures 5.55–6.25 mm (D) × 7.75–8.15 mm (E) × 1.90–2.45 mm (A1) and supports IPC7531-compliant footprint layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-voltage return path; defines unidirectional conduction direction. |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., 24 V battery rail); conducts transient current to ground during overvoltage. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive-grade reliability across temperature cycling, humidity, and mechanical shock per JESD22 standards. |
| ISO 7637-2 compliance | Withstands Pulse 1 (–150 V), Pulse 2a (+112 V), Pulse 3a (–220 V), and Pulse 3b (+150 V) on 24 V systems without degradation. |
| IEC 61000-4-2 ESD immunity | 30 kV contact and air discharge tolerance exceeds Level 4, eliminating need for external ESD filters on sensor interfaces. |
| Planar silicon construction | Enables stable 0.2 µA leakage at 25 °C and <100 nA at 125 °C, critical for low-power always-on ECUs. |
| MSL Level 1 rating | Unlimited floor life at ≤30 °C/85% RH, simplifying manufacturing logistics and eliminating bake requirements. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Protection |
|---|---|
|
Use Scenario: Protects 24 V supply input of diesel engine ECUs exposed to load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamps transients faster than fuse response time, preserving MCU and driver IC integrity. Use Value: Withstands ISO 7637-2 Pulse 5b (87 V, 400 ms) and maintains VCL ≤ 38.9 V at 129 A, preventing brownout or latch-up in safety-critical firmware. |
Use Scenario: Shields LIN transceiver pins from ESD and coupled noise in door module wiring harnesses. IC Role / Device Role / Timing Role: Acts as front-end surge suppressor ahead of LIN PHY, absorbing 30 kV contact discharge per ISO 10605. Use Value: 0.2 µA leakage avoids signal distortion on 12 V LIN bus; 27.0 mΩ RD ensures clamping within 1 ns of ESD onset. |
| Electric Power Steering (EPS) Motor Driver | e-Breaker Load Switch Protection |
|
Use Scenario: Guards half-bridge gate drivers against inductive kickback from 24 V EPS motor windings. IC Role / Device Role / Timing Role: Placed across motor phase outputs to clamp flyback voltage spikes during PWM switching. Use Value: 5000 W peak power rating handles repetitive 10/1000 µs transients; 175 °C Tj max supports compact heatsink-less PCB layout. |
Use Scenario: Integrated into solid-state e-breaker modules to protect MOSFETs during short-circuit interruption. IC Role / Device Role / Timing Role: Fast-clamping element that diverts fault current away from power switches during overcurrent events. Use Value: Matches ISO 16750-2 Test B (load dump) requirements; 38.9 V VCL prevents gate oxide rupture in 40 V-rated SiC drivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ24A | Lower PPP (400 W), higher VCL (43.5 V), SMC package, non-AEC-Q101 rated | Limited to non-automotive industrial use; insufficient for ISO 7637-2 Pulse 1 (–150 V) compliance | Select only for cost-sensitive 24 V consumer electronics with no automotive qualification requirement. |
| TPSMD24 | Same PPP (5000 W), but higher leakage (1 µA), lower Tj max (150 °C), and no ISO 7637-2 validation data | Not validated for automotive surge standards; requires additional system-level testing for e-breaker use | Acceptable for commercial-grade 24 V power supplies where AEC-Q101 and ISO compliance are not mandated. |
Compared with SMAJ24A and TPSMD24, SM50T28AY uniquely combines AEC-Q101 qualification, 175 °C operation, 0.2 µA leakage, and full ISO 7637-2 Pulse 1/2a/3a/3b validation-making it the only drop-in solution for production automotive e-breaker and ECU power rail designs requiring zero derating.
Availability
SM50T28AY is available at Aetrix Electronics and suitable for engine control units, body control modules, electric power steering systems, and e-breaker modules requiring stable component supply across automotive production lifecycles.
Supply support for SM50T28AY 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, delivering automotive, industrial, and power management solutions since 1987.
SM50T28AY belongs to the SM50TY series of planar TVS diodes engineered specifically for AEC-Q101-compliant automotive surge protection-targeting high-reliability 12 V and 24 V battery rail applications where long-term stability under thermal stress is mandatory.
FAQ
What is the maximum clamping voltage of SM50T28AY under ISO 7637-2 Pulse 3b conditions?
Under ISO 7637-2 Pulse 3b (VS = +150 V, 12 V battery system), SM50T28AY clamps to 38.9 V at 129 A (10/1000 µs). This value is measured at 25 °C and scales with junction temperature using αT = 10⁻⁴/°C; at 150 °C, VCL rises to approximately 42.1 V.
Can SM50T28AY replace bidirectional TVS diodes in LIN bus protection?
No-SM50T28AY is unidirectional and only protects against positive transients on the cathode side. For LIN bus (which experiences both positive and negative ESD events), a bidirectional variant like SM50T28CAY must be used to ensure symmetrical clamping across signal polarity swings.
How does SM50T28AY's dynamic resistance affect its performance in fast-rising transients?
With RD = 27.0 mΩ, SM50T28AY limits voltage overshoot during sub-microsecond events like IEC 61000-4-2 ESD (8/20 µs). This low impedance ensures VCL remains within 38.9 V even at 72.9 A peak current, reducing stress on downstream 3.3 V or 5 V logic interfaces.
Is SM50T28AY compatible with lead-free reflow profiles per J-STD-020?
Yes-SM50T28AY is qualified for MSL Level 1 and supports ST's recommended reflow profile: peak temperature 240–245 °C for 60 seconds (max 90 s), ramp rates ≤3 °C/s, and cooling rate ≥2 °C/s. Its matte tin plating ensures reliable solder joint formation without whisker growth.
SM50T28AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AB, SMC
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 24V (Max)
- Voltage - Breakdown (Min):
- 26.7V
- Voltage - Clamping (Max) @ Ipp:
- 38.9V
- Current - Peak Pulse (10/1000µs):
- 129A
- Power - Peak Pulse:
- 5000W (5kW)
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMC
SM50T28AY FAQ
1.How can I place an order for SM50T28AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM50T28AY 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 SM50T28AY reliable?
The price and inventory of SM50T28AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM50T28AY is usually 5 days.
3.What payment methods are accepted for SM50T28AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM50T28AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM50T28AY?
SM50T28AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM50T28AY 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 SM50T28AY?
For technical support, including SM50T28AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM50T28AY requirements.
6.How does Aetrix verify that SM50T28AY is sourced from the original manufacturer or authorized distributors?
All SM50T28AY 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 SM50T28AY meets industry standards.
7.What is the process for return or replacement of SM50T28AY?
All SM50T28AY units undergo pre-shipment inspection (PSI). If there is an issue with SM50T28AY, 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 SM50T28AY part is unused and in its original packaging.
Return procedure for SM50T28AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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