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STMicroelectronics SMAJ28CA-TR
- Part No.:
- SMAJ28CA-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CA-TR.pdf
- Description:
- TVS DIODE 28VWM 59VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:3,671
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Product details
Overview
SMAJ28CA-TR from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode designed for ESD and surge protection in low-voltage DC power rails and signal lines. It features a 28 V standoff voltage (VRM), 45.4 V maximum clamping voltage at 8.8 A (10/1000 µs), 400 W peak pulse power rating, and operates up to +150 °C junction temperature-commonly deployed in industrial I/O interfaces and automotive body electronics.
For engineers reviewing the SMAJ28CA-TR datasheet, SMAJ28CA-TR pinout, SMAJ28CA-TR application, or SMAJ28CA-TR equivalent, key selection criteria include bidirectional clamping behavior, low leakage (<1 µA at 85 °C), JEDEC DO-214AC (SMA) package compatibility, and IEC 61000-4-2/4-4 compliance for system-level EMC robustness.
Technical Context
This device uses planar silicon junction technology to achieve stable breakdown characteristics and low dynamic resistance (0.632 Ω at 8/20 µs), enabling fast response to transients while maintaining low leakage across temperature. Its bidirectional configuration supports symmetric surge suppression on AC-coupled or floating signal paths without polarity constraints.
The SMAJ28CA-TR complies with IEC 61000-4-2 level 4 (±30 kV air/contact discharge) and IEC 61000-4-4 level 4 (4 kV), with clamping performance validated under both 10/1000 µs (400 W) and 8/20 µs (2.3 kW) waveforms-making it suitable for front-end protection where energy absorption and voltage limiting must coexist.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 28 V - Maximum continuous reverse operating voltage before conduction begins. |
| Breakdown Voltage (VBR) | 31.1–32.7 V at 1 mA - Ensures reliable triggering margin above normal rail voltage. |
| Clamping Voltage (VCL) | 45.4 V at 8.8 A (10/1000 µs) - Limits transient voltage seen by downstream ICs to safe levels. |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - Sustains moderate-energy surges typical of industrial I/O coupling. |
| Leakage Current (IRM) | 0.2 µA at 25 °C, 1 µA at 85 °C - Minimizes standby power loss and avoids false triggering in high-impedance circuits. |
| Junction Temperature Range | −55 to +150 °C - Supports operation in under-hood automotive or sealed industrial enclosures. |
| Package | DO-214AC (SMA) - Standardized surface-mount footprint per IPC-7531, compatible with automated assembly. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with two coplanar cathode-anode terminals; dimensions per JEDEC MS-013 (EIAJ ED-732AA), 2.25–2.90 mm width, 4.80–5.35 mm length, 1.90–2.45 mm height; recommended PCB footprint per Figure 14 (DS1251 Rev 15).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Current entry terminal in forward bias; common reference for bidirectional clamping | Connected to protected line; forms symmetrical junction with cathode for equal clamping in both polarities. |
| Cathode (K) | Current exit terminal in forward bias; defines polarity reference | Also connected to protected line; dual-terminal symmetry enables AC or floating rail protection without orientation dependency. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional ESD protection | ±30 kV contact/air discharge per IEC 61000-4-2 level 4-eliminates need for separate polarity-specific devices on differential or AC signals. |
| Low dynamic resistance | 0.632 Ω at 8/20 µs-reduces clamping overshoot during fast-rising transients like lightning-induced surges. |
| High-temperature reliability | Rated to +150 °C junction temperature-enables use in engine control units and power supply front ends without derating. |
| JEDEC-compliant solderability | MSL level 1, matte tin-plated leads, J-STD-002/JESD22-B102 E3 qualified-ensures robust reflow yield and long-term interconnect integrity. |
| Planar junction construction | Enables <1 µA leakage at 85 °C-critical for battery-powered sensors and high-impedance analog monitoring circuits. |
Applications
| Industrial PLC I/O Modules | Automotive Body Control Units |
|---|---|
Use Scenario: Protection of 24 V CAN/LIN bus stubs and digital input channels against load dump and ESD events. IC Role / Device Role / Timing Role: Bidirectional TVS clamp placed directly at connector interface to shunt surge current before reaching MCU GPIO or transceiver. Use Value: Clamps 4 kV IEC 61000-4-4 surges to ≤45.4 V, preserving signal integrity and preventing latch-up in 3.3 V/5 V logic interfaces. | Use Scenario: Surge suppression on 12 V power inputs to door module microcontrollers and LED drivers. IC Role / Device Role / Timing Role: Primary overvoltage clamp on fused VBAT rail, coordinated with upstream fuse and downstream LDO. Use Value: Withstands 150 °C ambient under hood conditions while maintaining <1 µA leakage-reducing quiescent current drain in always-on modules. |
| Medical Patient Monitoring Ports | Smart Building Sensor Nodes |
Use Scenario: ESD protection on isolated RS-485/USB-C data ports handling patient-connected peripherals. IC Role / Device Role / Timing Role: Secondary protection stage after isolation barrier, absorbing residual transients that cross galvanic separation. Use Value: ±30 kV IEC 61000-4-2 immunity ensures no data corruption or reset during clinical staff handling with static-prone gowns. | Use Scenario: Transient suppression on 24 V PoE-powered Zigbee/Z-Wave sensor nodes exposed to HVAC-induced switching noise. IC Role / Device Role / Timing Role: Front-end clamp on DC input before buck converter, reducing stress on input capacitors and MOSFETs. Use Value: 400 W 10/1000 µs rating handles repetitive inductive kickback from relay coils without degradation over 10+ year field life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ28CA-TR | Higher 600 W peak power (10/1000 µs); larger SMB package (DO-214AA) | Better suited for higher-energy surges but requires more PCB area and thermal relief | Select when system-level testing shows >400 W surge exposure or when board layout allows larger footprint. |
| SMCJ28CA-TR | 1500 W peak power (10/1000 µs); SMC package (DO-214AB), higher VCL (48.4 V) | Used in primary power rail protection where clamping voltage margin permits higher VCL | Choose for main 24 V input protection where lower clamping voltage is less critical than energy handling. |
Compared with SMBJ28CA-TR and SMCJ28CA-TR, the SMAJ28CA-TR offers optimal balance of compact size, low leakage, and sufficient surge capability for secondary-side and signal-line protection-making it preferred where space, thermal constraints, and precision clamping are prioritized over raw energy absorption.
Availability
SMAJ28CA-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and medical patient monitoring ports requiring stable component supply and long-term lifecycle support.
Supply support for SMAJ28CA-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 power management, analog, MEMS, and microcontroller technologies for industrial, automotive, and consumer markets.
The SMAJ series belongs to ST's transient protection portfolio, engineered specifically for cost-effective, high-reliability ESD and surge suppression in space-constrained, thermally demanding applications-emphasizing low leakage, tight parameter distribution, and JEDEC-standard packaging.
FAQ
What is the difference between SMAJ28A-TR and SMAJ28CA-TR?
The "A" suffix denotes unidirectional TVS behavior (clamps only in reverse bias), while "CA" indicates bidirectional operation (symmetric clamping for both polarities). SMAJ28CA-TR is used on AC-coupled lines, differential buses, or floating rails where polarity is undefined or alternates-whereas SMAJ28A-TR suits DC power rails with defined ground reference.
Does SMAJ28CA-TR require external heat sinking?
No external heat sink is required under normal operation. Its DO-214AC package achieves ~140 °C/W junction-to-ambient thermal resistance on standard FR4 with 1 cm² copper per lead (per DS1251 Fig. 12). Derating is only needed for sustained repetitive surges exceeding 1 Hz or ambient temperatures above 105 °C.
Can SMAJ28CA-TR be used in parallel for higher surge current handling?
Parallel connection is not recommended due to mismatch in dynamic resistance and VBR tolerance (±5%), which causes uneven current sharing and potential thermal runaway. For higher current capability, select a single higher-rated device like SMBJ28CA-TR or SMCJ28CA-TR instead.
Is SMAJ28CA-TR compliant with RoHS and REACH?
Yes-SMAJ28CA-TR is manufactured in ST's ECOPACK2-compliant facilities and meets RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. Full material declarations and compliance certificates are available via ST's quality portal using order code SMAJ28CA-TR.
SMAJ28CA-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):
- 28V
- Voltage - Breakdown (Min):
- 31.1V
- Voltage - Clamping (Max) @ Ipp:
- 59V
- Current - Peak Pulse (10/1000µs):
- 39A (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)
SMAJ28CA-TR FAQ
1.How can I place an order for SMAJ28CA-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CA-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 SMAJ28CA-TR reliable?
The price and inventory of SMAJ28CA-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28CA-TR is usually 5 days.
3.What payment methods are accepted for SMAJ28CA-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CA-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CA-TR?
SMAJ28CA-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CA-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 SMAJ28CA-TR?
For technical support, including SMAJ28CA-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CA-TR requirements.
6.How does Aetrix verify that SMAJ28CA-TR is sourced from the original manufacturer or authorized distributors?
All SMAJ28CA-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 SMAJ28CA-TR meets industry standards.
7.What is the process for return or replacement of SMAJ28CA-TR?
All SMAJ28CA-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CA-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 SMAJ28CA-TR part is unused and in its original packaging.
Return procedure for SMAJ28CA-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ28CA-TR Tags
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Toshiba Semiconductor and Storage
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