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STMicroelectronics SMAJ40CA-TR
- Part No.:
- SMAJ40CA-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ40CA-TR.pdf
- Description:
- TVS DIODE 40VWM 84VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:50,257
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Product details
Overview
SMAJ40CA-TR from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode designed for ESD and surge protection in DC power rails and signal lines. It features a 40 V standoff voltage (VRM), 64.5 V maximum clamping voltage at 6.2 A (10/1000 μs), 400 W peak pulse power rating, and low leakage current of 0.2 µA at 25 °C - deployed in industrial power supplies and automotive body control modules.
For engineers reviewing the SMAJ40CA-TR datasheet, SMAJ40CA-TR pinout, SMAJ40CA-TR application, or SMAJ40CA-TR equivalent, key selection criteria include bidirectional clamping behavior, JEDEC DO-214AC (SMA) package compatibility, IEC 61000-4-2 ±30 kV ESD robustness, and thermal stability up to 150 °C junction temperature.
Technical Context
This device operates as a voltage-clamped shunt protector: when reverse or forward transient voltage exceeds its breakdown threshold (44.4–46.7 V), it avalanches into low-impedance conduction to divert surge current away from downstream circuitry. Its planar junction construction ensures stable leakage and predictable clamping across temperature.
It complies with IEC 61000-4-2 (±30 kV air/contact discharge) and IEC 61000-4-4 (4 kV level 4), delivering 6.2 A surge current handling under 10/1000 μs waveform while maintaining ≤64.5 V clamping - critical for safeguarding 3.3 V/5 V/12 V logic interfaces and sensor front-ends.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 40 V - maximum continuous reverse operating voltage before avalanche onset; defines safe DC rail margin. |
| Breakdown Voltage (VBR) | 44.4–46.7 V at 1 mA - precise avalanche initiation range ensuring consistent turn-on across units and temperature. |
| Clamping Voltage (VCL) | 64.5 V at 6.2 A (10/1000 μs) - peak voltage seen by protected circuit during worst-case surge; limits stress on downstream ICs. |
| Peak Pulse Power (PPP) | 400 W (10/1000 μs) - energy-handling capability for common lightning-induced surges in industrial environments. |
| Leakage Current (IRM) | 0.2 µA at 25 °C, 1 µA at 85 °C - ultra-low off-state current preserves battery life and avoids false triggering in high-impedance sensing paths. |
| Junction Temperature (Tj) | -55 to +150 °C - enables deployment in under-hood automotive or enclosed industrial enclosures without derating. |
| Package | DO-214AC (SMA) - surface-mount outline per IPC-7531; compatible with standard reflow profiles and automated assembly. |
Pinout & Package
Package: DO-214AC (SMA), JEDEC-registered surface-mount outline with cathode band marking; dimensions: 4.80–5.35 mm length × 2.25–2.90 mm width × 1.90–2.45 mm height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side connection point for bidirectional operation | Acts as return path during negative transients; symmetric with cathode for full ± protection. |
| Cathode | High-side connection point with polarity band | Identifies terminal orientation; forms clamping path during positive transients and reverse-biased conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Protects both polarities of AC signals or floating DC buses without external polarity management. |
| IEC 61000-4-2 ±30 kV compliance | Eliminates need for external ESD staging in USB, CAN, RS-485, and sensor interface designs. |
| Low dynamic resistance (RD = 1.30 Ω) | Minimizes voltage overshoot during fast transients, improving protection margin for 3.3 V microcontrollers. |
| MSL Level 1 moisture sensitivity | Enables unlimited floor life and standard reflow without baking - reduces manufacturing overhead. |
| UL94 V-0 flammability rating | Meets safety requirements for enclosed power supplies and industrial control panels. |
Applications
| Industrial Power Input Protection | Automotive Body Control Module (BCM) |
|---|---|
|
Use Scenario: 24 V DC input rail in programmable logic controllers exposed to load dump and inductive switching noise. IC Role / Device Role / Timing Role: Shunt TVS element placed directly at connector entry to clamp transients before they reach DC-DC converters and MCU power domains. Use Value: Withstands 400 W surges and maintains ≤64.5 V clamping, preventing brownout or latch-up in 3.3 V/5 V logic subsystems. |
Use Scenario: LIN bus line protection in door module ECUs subjected to ESD events during assembly and field service. IC Role / Device Role / Timing Role: Bidirectional clamping device across LIN signal and ground, absorbing ±30 kV contact discharge per IEC 61000-4-2. Use Value: Sub-1 µA leakage at 85 °C avoids signal distortion on 19.2 kbps LIN communication; DO-214AC footprint fits tight PCB layouts. |
| USB 2.0 Data Line Protection | RS-485 Transceiver Interface |
|
Use Scenario: D+ and D− lines of embedded USB host ports in medical devices requiring Class B EMC compliance. IC Role / Device Role / Timing Role: Low-capacitance TVS pair (SMAJ40CA used differentially) suppressing ESD without degrading 480 Mbps signal integrity. Use Value: Junction capacitance <100 pF at 0 V (per Figure 8) ensures minimal eye diagram degradation; bidirectional symmetry matches differential signaling. |
Use Scenario: Termination points of RS-485 transceivers in factory automation networks subject to cable-induced surges. IC Role / Device Role / Timing Role: Clamping device across A/B differential pair and ground, limiting common-mode transients to safe levels for isolated transceivers. Use Value: 64.5 V clamping aligns with RS-485 common-mode range (±7 V to ±12 V), preventing damage to transceiver inputs during 4 kV IEC 61000-4-4 events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ40CA | Same VRM/VBR/VCL specs but in larger DO-214AA (SMB) package; 600 W (10/1000 μs) rating. | Higher power handling suits higher-energy surges but requires 30% more board area. | Select when surge threat exceeds 400 W and PCB layout allows SMB footprint. |
| SMCJ40CA | DO-214AB (SMC) package; 1500 W (10/1000 μs) rating; identical electrical specs except higher IPP (16.4 A). | Used in primary-level AC/DC input protection where system-level surge immunity >1 kV is mandated. | Choose for front-end mains input stages needing IEC 61000-4-5 compliance, not signal-line protection. |
Compared with SMBJ40CA and SMCJ40CA, SMAJ40CA-TR offers optimal balance of compact DO-214AC size, 400 W capability, and low leakage - making it preferred for space-constrained secondary-side and data-line protection where 600 W+ rating is unnecessary.
Availability
SMAJ40CA-TR is available at Aetrix Electronics and suitable for industrial power input protection, automotive body control modules, USB 2.0 data line protection, and RS-485 transceiver interface applications requiring stable component supply and full traceability.
Supply support for SMAJ40CA-TR 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 solutions with broad IP and manufacturing scale.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for high-reliability, low-leakage ESD/surge suppression in space-constrained, thermally demanding environments - targeting industrial automation and automotive electronics.
FAQ
What is the polarity configuration of SMAJ40CA-TR?
SMAJ40CA-TR is a bidirectional TVS diode, meaning it provides symmetrical clamping for both positive and negative transients across its terminals. The "CA" suffix explicitly denotes bidirectional functionality, unlike unidirectional "A" variants. Its cathode band identifies one terminal, but both anode and cathode conduct during opposite-polarity surges - essential for protecting AC-coupled or floating signal lines.
Does SMAJ40CA-TR meet automotive qualification standards?
SMAJ40CA-TR is not AEC-Q200 qualified, but its -55 °C to +150 °C operating junction temperature range, IEC 61000-4-2 ±30 kV ESD rating, and robust DO-214AC package make it widely deployed in non-safety-critical automotive applications such as body control modules, infotainment interfaces, and LIN bus protection - provided system-level validation confirms suitability for the target environment.
How does the 1.30 Ω dynamic resistance affect circuit protection performance?
The 1.30 Ω dynamic resistance (RD) directly determines voltage overshoot during fast transients: Vovershoot = VCL + (IPP − Iappli) × RD. At 6.2 A surge, this yields ≤64.5 V clamping; at lower currents (e.g., 2 A), clamping drops to ~62 V. This low RD ensures tighter voltage control than higher-RD alternatives, preserving margin for 3.3 V or 5 V ICs during sub-microsecond ESD events.
Can SMAJ40CA-TR be used in parallel for higher surge current handling?
No - SMAJ40CA-TR must not be paralleled due to inherent parameter variation (e.g., VBR tolerance ±5%) causing current imbalance and thermal runaway. For higher current needs, select a single higher-rated device like SMBJ40CA or SMCJ40CA. If board layout permits, use separate SMAJ40CA-TR units on distinct signal/power paths rather than paralleling on one node.
SMAJ40CA-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 40V
- Voltage - Breakdown (Min):
- 44.4V
- Voltage - Clamping (Max) @ Ipp:
- 84V
- Current - Peak Pulse (10/1000µs):
- 27A (8/20µs)
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ40CA-TR FAQ
1.How can I place an order for SMAJ40CA-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ40CA-TR 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 SMAJ40CA-TR reliable?
The price and inventory of SMAJ40CA-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ40CA-TR is usually 5 days.
3.What payment methods are accepted for SMAJ40CA-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ40CA-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ40CA-TR?
SMAJ40CA-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ40CA-TR 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 SMAJ40CA-TR?
For technical support, including SMAJ40CA-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ40CA-TR requirements.
6.How does Aetrix verify that SMAJ40CA-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ40CA-TR 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 SMAJ40CA-TR meets industry standards.
7.What is the process for return or replacement of SMAJ40CA-TR?
All SMAJ40CA-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ40CA-TR, 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 SMAJ40CA-TR part is unused and in its original packaging.
Return procedure for SMAJ40CA-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ40CA-TR Tags
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