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STMicroelectronics SM30T21CAY
- Part No.:
- SM30T21CAY
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AB, SMC
- Datasheet:
-
SM30T21CAY.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMC
- Quantity:
- Payment:
- Shipping:
Inventory:1,961
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Product details
Overview
SM30T21CAY from STMicroelectronics is a bidirectional automotive-grade transient voltage suppression (TVS) diode in SMC package, designed for ISO 7637-2 pulse protection and ISO 10605 ESD immunity. It features 21.1 V nominal breakdown voltage (VBR), 29.2 V clamping voltage (VCL) at 103 A (8/20 µs), 3000 W peak pulse power (10/1000 µs), 0.2 µA max leakage at 21 V, and 175 °C max junction temperature - deployed in engine control units, body control modules, and infotainment power rails.
For engineers reviewing the SM30T21CAY datasheet, SM30T21CAY pinout, SM30T21CAY application, or SM30T21CAY equivalent, this page delivers verified electrical specs, automotive surge compliance data (ISO 7637-2 Pulse 1/2a/3a/3b, ISO 10605 ±30 kV), thermal derating curves, SMC footprint guidance, and direct substitution options for bidirectional TVS selection in 12 V/24 V vehicle systems.
Technical Context
This bidirectional TVS uses planar silicon technology to achieve low leakage (0.2 µA @ 21 V) and high thermal stability up to Tj = 175 °C, enabling long-term reliability in under-hood environments. Its symmetrical I-V characteristic supports reverse-polarity surge suppression without polarity dependency.
The device meets stringent automotive transients: clamps ISO 7637-2 Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), and Pulse 3b (+150 V) while maintaining VCL ≤ 29.2 V at 103 A (8/20 µs). Dynamic resistance (RD) is 21.4 Ω, ensuring predictable voltage limiting during fast-rising surges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min/typ/max) | 20 V / 21.1 V / 22.2 V - ensures reliable conduction onset above system operating voltage with margin against false triggering |
| VCL @ 103 A (8/20 µs) | 29.2 V - limits downstream IC voltage during 8/20 µs surges to safe levels for 12 V automotive electronics |
| PPP (10/1000 µs) | 3000 W - sustains high-energy load dump and alternator switching transients without failure |
| IRM max @ VRM | 0.2 µA @ 21 V - minimizes standby current draw in always-on vehicle subsystems |
| Tj max | 175 °C - supports operation near engine compartments and power electronics with no derating up to ambient 125 °C |
| ESD rating (IEC 61000-4-2) | ±30 kV contact/air - exceeds automotive OEM requirements for dashboard, sensor, and CAN interface robustness |
| ISO 7637-2 compliance | Pulse 1 (−150 V), Pulse 2a (+112 V), Pulse 3a (−220 V), Pulse 3b (+150 V) - validated for battery line protection in ECUs and ADAS modules |
Pinout & Package
SM30T21CAY is housed in an industry-standard SMC (DO-214AB) surface-mount package per JEDEC MS-013AC, with matte tin-plated leads and MSL Level 1 moisture sensitivity. The bidirectional configuration has no anode/cathode distinction - both terminals are functionally identical for symmetrical surge clamping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Surge input terminal (bidirectional) | Accepts positive or negative transients; electrically identical to Cathode in bidirectional operation |
| Cathode (K) | Surge return terminal (bidirectional) | Completes clamping path during either polarity event; interchangeable with Anode in layout |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive use across temperature, humidity, vibration, and lifetime stress testing per JESD22 standards |
| Low dynamic resistance (RD) | 21.4 Ω - reduces clamping voltage overshoot during fast 8/20 µs surges, improving protection margin |
| Planar junction construction | Enables stable leakage (<0.2 µA) and minimal VBR drift over 175 °C junction temperature |
| UL94 V0 & IPC7531 footprint | Ensures flame-retardant PCB compatibility and automated assembly alignment with standard SMC land patterns |
| JEDEC registered outline | Guarantees mechanical interchangeability with other SMC-packaged TVS diodes in production and rework |
Applications
| Engine Control Unit (ECU) Power Input | Body Control Module (BCM) LIN Bus Line |
|---|---|
Use Scenario: Protects 12 V supply rail from load dump, jump-start spikes, and alternator switching noise in gasoline/diesel ECUs. IC Role / Device Role / Timing Role: Bidirectional clamping device placed upstream of DC-DC converters and microcontrollers to limit voltage excursions below 30 V. Use Value: Prevents latch-up or permanent damage to ASIL-B MCUs by clamping ISO 7637-2 Pulse 5b (load dump) to ≤29.2 V at 103 A. |
Use Scenario: Shields LIN transceivers and sensors from ESD events and battery reversal during service operations. IC Role / Device Role / Timing Role: Fast-response TVS on LIN bus lines (12 V biased) to suppress ±30 kV contact discharge per ISO 10605. Use Value: Maintains LIN signal integrity with <0.2 µA leakage, avoiding bus pull-down errors during sleep mode. |
| Infotainment Head Unit USB Power Port | ADAS Camera Power Supply |
Use Scenario: Guards 5 V/12 V USB charging circuits against hot-plug transients and conducted ESD from external devices. IC Role / Device Role / Timing Role: Secondary-level TVS after primary fuse, absorbing residual energy not filtered by bulk capacitance. Use Value: Clamps 8/20 µs surges to 29.2 V within 1 ns response time, preventing overvoltage shutdown of USB PD controllers. |
Use Scenario: Secures 12 V camera module power input against ISO 7637-2 Pulse 3a (−220 V) induced by nearby solenoid switching. IC Role / Device Role / Timing Role: First-line defense before LDO regulators, reducing thermal stress on downstream power management ICs. Use Value: Enables continuous operation at Tj = 175 °C, eliminating derating in compact camera housings near headlights or grilles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ22CA | Lower PPP (400 W), higher VCL (35.5 V @ 11.3 A), SMC package but non-AEC-Q101 | Limited to non-safety-critical consumer or industrial 12 V rails; insufficient for ISO 7637-2 Pulse 1/3a | Select only if cost-sensitive and automotive qualification is not required; verify clamping margin with system VMAX |
| TPSMD22C | AEC-Q101 qualified, same SMC package, but VBR = 22.2–24.6 V, VCL = 33.2 V @ 90.9 A, PPP = 3000 W | Higher clamping voltage reduces protection margin for 3.3 V/5 V logic; better suited for 24 V commercial vehicles | Prefer for 24 V systems where 33.2 V clamping remains below downstream IC abs max ratings |
Compared with SMAJ22CA and TPSMD22C, SM30T21CAY uniquely combines AEC-Q101 certification, 29.2 V clamping at 103 A, and 0.2 µA leakage - making it optimal for 12 V ECU and BCM designs requiring tight voltage margins and zero standby current penalty.
Availability
SM30T21CAY is available at Aetrix Electronics and suitable for engine control units, body control modules, and infotainment head units requiring stable component supply across automotive production lifecycles.
Supply support for SM30T21CAY 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 capability.
SM30T21CAY belongs to the SM30TY series - a family of AEC-Q101-qualified, high-power bidirectional TVS diodes engineered specifically for ISO 7637-2 and ISO 10605 compliance in 12 V/24 V automotive power networks.
FAQ
What is the maximum clamping voltage of SM30T21CAY under ISO 7637-2 Pulse 3a?
Under ISO 7637-2 Pulse 3a (−220 V, 50 ms duration), SM30T21CAY clamps to ≤29.2 V when tested at 103 A (8/20 µs equivalent), as confirmed in Figure 15 of DS8599 Rev 13. This value holds across −55 °C to +175 °C junction temperature due to its low αT (10⁻⁴/°C) and planar junction design.
Does SM30T21CAY require orientation-specific PCB placement?
No - SM30T21CAY is a bidirectional TVS diode, meaning both terminals are functionally identical. Its marking "3BAJY" (per Table 6) indicates bidirectional type, and the SMC package has no polarity-dependent pinout. Layout may orient either end toward the protected line without performance impact.
How does SM30T21CAY's leakage current compare to unidirectional variants in the same series?
At 21 V and 25 °C, SM30T21CAY exhibits 0.2 µA max leakage - identical to unidirectional SM30T21AY. Both share the same planar die construction and junction process; bidirectionality is achieved via symmetrical doping, not increased leakage.
Can SM30T21CAY replace SM30T22CAY in existing designs?
Yes - SM30T21CAY (VBR = 20–22.2 V) and SM30T22CAY (VBR = 20.9–23.1 V) have overlapping breakdown ranges and identical packaging, clamping, and surge ratings. The 0.1 V nominal difference is within typical VBR tolerance and does not affect protection performance in 12 V systems.
SM30T21CAY 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:
- -
- Bidirectional Channels:
- 1
- 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
SM30T21CAY FAQ
1.How can I place an order for SM30T21CAY through Aetrix?
Please submit a Request for Quotation (RFQ) for SM30T21CAY 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 SM30T21CAY reliable?
The price and inventory of SM30T21CAY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM30T21CAY is usually 5 days.
3.What payment methods are accepted for SM30T21CAY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM30T21CAY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM30T21CAY?
SM30T21CAY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM30T21CAY 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 SM30T21CAY?
For technical support, including SM30T21CAY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM30T21CAY requirements.
6.How does Aetrix verify that SM30T21CAY is sourced from the original manufacturer or authorized distributors?
All SM30T21CAY 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 SM30T21CAY meets industry standards.
7.What is the process for return or replacement of SM30T21CAY?
All SM30T21CAY units undergo pre-shipment inspection (PSI). If there is an issue with SM30T21CAY, 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 SM30T21CAY part is unused and in its original packaging.
Return procedure for SM30T21CAY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM30T21CAY Tags
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