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STMicroelectronics SM30T21AY
- Part No.:
- SM30T21AY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM30T21AY.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:7,542
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Product details
Overview
SM30T21AY from STMicroelectronics is a unidirectional 3000 W automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection in 12 V/24 V vehicle systems. It features a 21.1 V nominal breakdown voltage (VBR), 29.2 V clamping voltage (VCL) at 103 A (10/1000 µs), 0.2 µA leakage at 25 °C, and AEC-Q101 qualification for under-hood applications.
For engineers reviewing the SM30T21AY datasheet, SM30T21AY pinout, SM30T21AY application, or SM30T21AY equivalent, this device serves as a high-reliability surge protector for power line and signal line interfaces in automotive ECUs, body control modules, and infotainment power supplies where junction temperature up to +175 °C and low dynamic resistance (21.4 mΩ) are critical.
Technical Context
The SM30T21AY employs planar silicon avalanche technology optimized for fast response (<1 ps) to ESD and surge transients per ISO 10605 (±30 kV air/contact discharge) and ISO 7637-2 (Pulse 1: −150 V; Pulse 2a: +112 V; Pulse 3a: −220 V; Pulse 3b: +150 V). Its unidirectional configuration enables robust reverse-biased clamping on DC power rails without forward conduction during normal operation.
Thermal performance is validated across −55 °C to +175 °C operating junction range, with JEDEC-registered SMC package enabling 260 °C soldering and IPC-7531-compliant footprint. Dynamic resistance of 21.4 mΩ ensures minimal voltage overshoot under 103 A surge current, while low leakage (0.2 µA at VRM = 18 V) preserves battery drain integrity in always-on circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 20.0 / 21.1 / 22.2 V - Ensures reliable triggering above system nominal voltage while avoiding false clamping during load dump transients. |
| VCL @ 10/1000 µs | 29.2 V at 103 A - Limits downstream IC voltage stress to safe levels during ISO 7637-2 Pulse 1 and Pulse 3a events. |
| IPP (10/1000 µs) | 103 A - Supports 3000 W peak pulse power dissipation at Tj = 25 °C for sustained surge immunity. |
| IR @ VRM | 0.2 µA at 18 V - Minimizes standby current draw in battery-connected modules, extending sleep-mode lifetime. |
| Tj max | +175 °C - Enables direct mounting near high-temperature engine control units without derating. |
| Dynamic RD | 21.4 mΩ - Reduces clamping voltage rise under high-current surges, improving protection margin for 5 V/3.3 V logic rails. |
| ESD rating | ±30 kV (IEC 61000-4-2, C = 150 pF/R = 330 Ω) - Exceeds automotive OEM requirements for touch-sensitive and sensor interfaces. |
Pinout & Package
The SM30T21AY is housed in a JEDEC-registered SMC (DO-214AB) surface-mount package with matte tin-plated leads and IPC-7531-compliant footprint. Dimensions: 5.55–6.25 mm (L) × 7.75–8.15 mm (W) × 2.45 mm (H), weight 0.25 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (marked side) | Surge current sink | Connected to protected line (e.g., battery rail); conducts avalanche current during overvoltage events. |
| Anode | Reference/ground return | Connected to chassis or system ground; completes clamping path with minimal inductance for fast transient response. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use including thermal cycling, humidity, and mechanical shock per JESD22 standards. |
| Low leakage current | 0.2 µA at 25 °C ensures <1 µA total standby drain in multi-diode protection networks for always-on ECUs. |
| High Tj capability | +175 °C maximum junction temperature allows placement adjacent to power MOSFETs or DC-DC converters without thermal derating. |
| ISO 7637-2 compliance | Withstands Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) without degradation in 12 V/24 V systems. |
| Planar silicon construction | Delivers consistent VBR tolerance (±5%) and stable dynamic resistance across production lots and temperature extremes. |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Line |
|---|---|
Use Scenario: Protects 12 V supply input of gasoline/diesel engine ECUs against alternator load dump and ISO 7637-2 Pulse 5b transients. IC Role / Device Role / Timing Role: Unidirectional TVS diode clamps reverse-polarity and high-energy surges before they reach the main DC-DC converter and microcontroller power rails. Use Value: Maintains VCL ≤ 29.2 V during 103 A surges, preventing latch-up or permanent damage to 3.3 V/5 V logic ICs downstream. | Use Scenario: Shields LIN physical layer transceivers from ESD and coupled noise on vehicle body wiring harnesses. IC Role / Device Role / Timing Role: Low-capacitance (≈100 pF) unidirectional clamp placed between LIN bus and ground, suppressing ±30 kV contact discharges without distorting 19.2 kbps signaling. Use Value: Leakage <0.2 µA avoids bias current errors in LIN master/slave termination resistors, preserving bus voltage stability. |
| Infotainment System USB Power Port | ADAS Camera Power Supply |
Use Scenario: Guards 5 V USB charging port in head unit against hot-swap transients and cable-induced surges in 24 V commercial vehicles. IC Role / Device Role / Timing Role: Fast-response TVS placed upstream of USB power switch IC, limiting VCL to 29.2 V during 10/1000 µs surges to protect internal LDOs and USB PHYs. Use Value: 21.4 mΩ dynamic resistance minimizes voltage overshoot during 103 A events, ensuring USB enumeration remains functional post-surge. | Use Scenario: Secures 12 V power input of rear-view or surround-view cameras exposed to harsh under-vehicle environments. IC Role / Device Role / Timing Role: High-Tj (175 °C) TVS mounted directly on camera PCB near connector, clamping ISO 7637-2 Pulse 3a (−220 V) without thermal runaway. Use Value: Stable 21.1 V VBR tolerance prevents premature conduction during cold-cranking dips, ensuring continuous image capture during engine start. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20A | Lower peak power (400 W), higher VCL (32.4 V at 12.3 A), SMC package but not AEC-Q101 qualified. | Restricted to non-automotive industrial or consumer power rails; unsuitable for ISO 7637-2 Pulse 1 or automotive ECU use. | Select only for cost-sensitive non-automotive designs where 3000 W surge immunity is unnecessary. |
| TPSMA6.8A-Q1 | AEC-Q101 qualified, same SMC package, but lower VBR (6.8 V) and VCL (11.2 V); rated for 400 W (10/1000 µs). | Designed for 5 V/3.3 V logic rail protection, not 12 V/24 V power line clamping; insufficient energy handling for load dump. | Use only for low-voltage signal line protection; cannot replace SM30T21AY in battery-supplied power domains. |
Compared with SMAJ20A and TPSMA6.8A-Q1, the SM30T21AY uniquely delivers AEC-Q101 validation, 3000 W surge capacity, and 21.1 V VBR in a single SMC device-enabling direct replacement of legacy TVS arrays in automotive power distribution units while reducing BOM count and PCB area.
Availability
SM30T21AY is available at Aetrix Electronics and suitable for automotive engine control units, body control modules, infotainment power supplies, and ADAS camera systems requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for SM30T21AY 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 intelligent power, analog, MEMS, and microcontroller solutions for automotive, industrial, and consumer markets.
The SM30TxxAY series belongs to ST's automotive-grade TVS portfolio, engineered specifically to meet stringent ISO 7637-2, ISO 10605, and AEC-Q101 requirements for power line surge protection in modern vehicle electronic architectures.
FAQ
What is the maximum clamping voltage of SM30T21AY under a 10/1000 µs surge?
The SM30T21AY exhibits a maximum clamping voltage (VCL) of 29.2 V when subjected to a 103 A, 10/1000 µs surge waveform at Tj = 25 °C. This value is measured per IEC 61000-4-5 and confirmed in Table 2 of DS8599 Rev 13. At elevated junction temperatures, VCL increases linearly with αT = 9.2 × 10−4/°C, reaching ~31.5 V at Tj = 150 °C.
Is SM30T21AY suitable for bidirectional signal line protection?
No-SM30T21AY is a unidirectional TVS diode intended for DC power rail protection (e.g., battery inputs), where clamping occurs only during reverse overvoltage events. For bidirectional signal lines like CAN or LIN, ST offers the complementary SM30T21CAY variant, which provides symmetrical clamping in both polarities and is marked "3BAJY" per Table 6.
How does the dynamic resistance (RD) affect circuit protection performance?
The SM30T21AY has a measured dynamic resistance of 21.4 mΩ, meaning its clamping voltage rises by ~2.2 V per 100 A of surge current beyond the initial VCL point. This low RD minimizes overshoot during fast-rising transients (e.g., ISO 7637-2 Pulse 3b), preserving margin for downstream 28 V-rated components and reducing stress on decoupling capacitors.
Can SM30T21AY be used in 24 V commercial vehicle systems?
Yes-its 21.1 V VBR and 29.2 V VCL provide adequate margin above 24 V nominal systems, and it fully complies with ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), and Pulse 3b (+150 V) test profiles. The +175 °C Tj rating supports under-hood deployment in heavy-duty trucks and buses where ambient temperatures exceed 105 °C.
SM30T21AY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AB, SMC
- Series:
- SM30TY, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 102.7A
- Power - Peak Pulse:
- 3000W (3kW)
- 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
SM30T21AY FAQ
1.How can I place an order for SM30T21AY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM30T21AY 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 SM30T21AY reliable?
The price and inventory of SM30T21AY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T21AY is usually 5 days.
3.What payment methods are accepted for SM30T21AY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T21AY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM30T21AY?
SM30T21AY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM30T21AY 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 SM30T21AY?
For technical support, including SM30T21AY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T21AY requirements.
6.How does Aetrix verify that SM30T21AY is sourced from the original manufacturer or authorized distributors?
All SM30T21AY 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 SM30T21AY meets industry standards.
7.What is the process for return or replacement of SM30T21AY?
All SM30T21AY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T21AY, 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 SM30T21AY part is unused and in its original packaging.
Return procedure for SM30T21AY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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