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Taiwan Semiconductor Corporation SMAJ28CH
- Part No.:
- SMAJ28CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CH.pdf
- Description:
- TVS DIODE 28VWM 50VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:4,569
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Product details
Overview
SMAJ28CH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 28V working stand-off voltage (VWM), 31.1–38.0V breakdown voltage (VBR), and 50.0V clamping voltage (VC) at 8.0A peak pulse current. It meets AEC-Q101 qualification and ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.
For engineers reviewing the SMAJ28CH datasheet, SMAJ28CH pinout, SMAJ28CH application, or SMAJ28CH equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, lighting drivers, and automotive body electronics where fast response (<1.0ps), low leakage (<1µA), and high surge immunity are critical.
Technical Context
The SMAJ28CH employs a glass-passivated silicon junction optimized for unidirectional transient suppression. Its clamping behavior is defined by a 10/1000μs waveform with 400W peak pulse power rating at TA = 25°C, derating linearly above that temperature per Fig.2. The device operates across –55°C to +150°C junction range and exhibits <3.5V forward voltage at 25A surge.
Designed for bidirectional-capable families but configured as unidirectional (no "CH" suffix implies cathode-marked polarity), SMAJ28CH features moisture sensitivity level 1 (J-STD-020), RoHS compliance, and halogen-free molding compound meeting IEC 61249-2-21. It supports automated placement and passes JESD 201 Class 2 whisker testing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before conduction begins |
| VBR @ IT=1mA | 31.1–38.0 V - Breakdown threshold range ensuring reliable turn-on during transients |
| VC @ IPPM=8.0A | 50.0 V - Clamped voltage limiting downstream circuit stress during 10/1000μs surge |
| PPPM | 400 W - Peak pulse power handling capability under standard 10/1000μs waveform |
| IR @ VWM | <1 µA - Ultra-low leakage preserving efficiency in high-impedance bias networks |
| TJ Range | –55°C to +150°C - Enables deployment in under-hood automotive and industrial environments |
| Response Time | <1.0 ps - Sub-picosecond junction response ensures protection before IC damage occurs |
Pinout & Package
DO-214AC (SMA) surface-mount package with matte tin-plated leads, polarity indicated by cathode band. Weight ≈ 0.060 g. Molding compound rated UL 94V-0.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., GND or return path) in unidirectional configuration |
| Cathode | Reverse-biased terminal | Marked end; connected to protected line (e.g., 28V rail) - conducts when Vin exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD stress |
| Glass passivated junction | Enhances long-term stability and reduces parameter drift under thermal/humidity stress |
| ISO 7637-2 compliance | Withstands standardized automotive load dump and switching transient waveforms without failure |
| Fast response time <1.0 ps | Protects sensitive logic and power management ICs before transient energy couples into system |
| Moisture sensitivity level 1 | Enables standard SMT reflow without baking or special handling requirements |
Applications
| Automotive Body Control Module (BCM) | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting LIN bus interface and microcontroller I/O lines against load dump and inductive kickback in door modules and lighting controllers. IC Role / Device Role / Timing Role: Unidirectional TVS clamp on 12V supply rail and signal lines, absorbing up to 400W surges while maintaining sub-1µA leakage. Use Value: Prevents latch-up or permanent damage to 3.3V/5V logic ICs during ISO 7637-2 Pulse 2b (inductive switch-off) events. | Use Scenario: Safeguarding primary-side MOSFET gate drivers and controller ICs in isolated 48V-to-12V buck converters used in factory automation. IC Role / Device Role / Timing Role: Standoff-rated TVS placed across input capacitor to clamp line transients before they reach PWM controller and gate driver stages. Use Value: Limits clamped voltage to 50.0V, keeping stress below 60V absolute maximum ratings of common 65V-rated controllers and drivers. |
| LED Streetlight Driver | Medical Power Adapter Input |
Use Scenario: Suppressing lightning-induced surges on AC/DC front-end rectified output feeding constant-current LED strings. IC Role / Device Role / Timing Role: Secondary-side unidirectional TVS on 28V DC bus, triggered only during overvoltage events exceeding 31.1V. Use Value: Maintains system uptime by preventing catastrophic failure of LED driver ICs during 1kV/0.5kA surge tests per IEC 61000-4-5. | Use Scenario: Providing secondary-side overvoltage protection on isolated 28V auxiliary rails powering monitoring sensors and communication interfaces. IC Role / Device Role / Timing Role: Low-leakage (≤1µA) TVS ensuring minimal standby current draw while delivering 400W surge capacity. Use Value: Meets essential safety margin requirements for medical-grade adapters without compromising no-load efficiency or thermal performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A | Lower VBR range (31.1–34.4V); tighter tolerance; same VC = 45.4V at 8.8A | Better suited for precision-clamp designs requiring lower turn-on uncertainty | Select SMAJ28A when tighter VBR distribution improves margin control in regulated 28V systems |
| SMBJ28C | Same VWM/VBR/VC, but SMB package (DO-214AA); 600W PPPM; higher IFSM = 100A | Higher surge rating and larger footprint - preferred for high-reliability industrial mains input stages | Choose SMBJ28C where PCB layout allows larger package and 600W surge headroom is required |
Compared with SMAJ28A and SMBJ28C, SMAJ28CH offers balanced 400W surge capability in compact DO-214AC, AEC-Q101 qualification for automotive use, and optimal leakage/clamping trade-off for space-constrained 28V rail protection.
Availability
SMAJ28CH is available at Aetrix Electronics and suitable for automotive body electronics, industrial DC/DC converter inputs, LED lighting drivers, and medical power adapter designs requiring stable component supply and full traceability.
Supply support for SMAJ28CH 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
Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, MOSFETs, and power management devices.
The SMAJ series was developed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing AEC-Q101 compliance, ISO 7637-2 immunity, and robust packaging for automated SMT assembly.
FAQ
What is the clamping voltage of SMAJ28CH and how is it measured?
The SMAJ28CH has a maximum clamping voltage (VC) of 50.0 V at 8.0 A peak pulse current (IPPM), tested using the standardized 10/1000 μs double-exponential waveform per Fig.5. This value represents the upper limit of voltage seen by downstream circuitry during a transient event, ensuring protected components remain within safe operating limits. The SMAJ28CH achieves this clamping performance while maintaining low leakage and fast response.
Is SMAJ28CH suitable for automotive applications?
Yes, SMAJ28CH is AEC-Q101 qualified and explicitly designed for automotive use. It meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements for transient immunity on vehicle power networks. Its –55°C to +150°C operating junction temperature range, moisture sensitivity level 1, and glass-passivated junction support under-hood and body-control module deployments. SMAJ28CH delivers proven reliability in automotive-grade power rail protection.
What does the "CH" suffix indicate in SMAJ28CH?
The "CH" suffix in SMAJ28CH denotes a unidirectional TVS diode with cathode-band polarity marking and compliance with AEC-Q101. It distinguishes the part from bidirectional variants (e.g., SMAJ28C) and confirms its intended use in DC circuits where reverse conduction must be blocked. The "H" indicates high-temperature reliability grade, and "C" specifies the unidirectional configuration - all confirmed in Taiwan Semiconductor's ordering code table and electrical specifications.
How does SMAJ28CH compare to SMAJ28AH in terms of breakdown voltage?
SMAJ28CH has a VBR range of 31.1–38.0 V at IT = 1 mA, whereas SMAJ28AH specifies 31.1–34.4 V - a tighter 3.3 V span versus 6.9 V. This means SMAJ28AH provides more predictable turn-on behavior in precision-clamp applications, while SMAJ28CH offers broader tolerance for cost-sensitive or less critical surge paths. Both share identical VWM = 28 V, VC = 50.0 V, and 400W PPPM, making SMAJ28CH ideal where wider VBR margin is acceptable.
Can SMAJ28CH be used in bidirectional configurations?
No, SMAJ28CH is strictly unidirectional and must not be used in bidirectional applications. Its cathode-band marking and electrical characteristics apply only in one polarity. For bidirectional operation, Taiwan Semiconductor specifies parts with "C" or "CAH" suffixes (e.g., SMAJ28C). Using SMAJ28CH in reverse-biased AC or differential-signal paths risks failure due to lack of symmetrical breakdown. Always verify polarity alignment in schematic and layout for SMAJ28CH.
SMAJ28CH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- 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:
- 50V
- Current - Peak Pulse (10/1000µs):
- 8A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ28CH FAQ
1.How can I place an order for SMAJ28CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CH 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 SMAJ28CH reliable?
The price and inventory of SMAJ28CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28CH is usually 5 days.
3.What payment methods are accepted for SMAJ28CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CH?
SMAJ28CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CH 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 SMAJ28CH?
For technical support, including SMAJ28CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CH requirements.
6.How does Aetrix verify that SMAJ28CH is sourced from the original manufacturer or authorized distributors?
All SMAJ28CH 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 SMAJ28CH meets industry standards.
7.What is the process for return or replacement of SMAJ28CH?
All SMAJ28CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CH, 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 SMAJ28CH part is unused and in its original packaging.
Return procedure for SMAJ28CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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