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Taiwan Semiconductor Corporation SMAJ28C
- Part No.:
- SMAJ28C
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28C.pdf
- Description:
- 400W, 34.6V, 10%, BIDIRECTIONAL,
- Quantity:
- Payment:
- Shipping:
Inventory:5,680
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Product details
Overview
SMAJ28C 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) at 1mA test current, and 50.0V maximum clamping voltage (VC) at 8.0A peak impulse current. It protects DC/DC converters and SMPS inputs against ISO 7637-2 Pulse 1/2a/2b/3a/3b transients.
For engineers reviewing the SMAJ28C datasheet, SMAJ28C pinout, SMAJ28C application, or SMAJ28C equivalent, key selection criteria include clamping performance under 10/1000μs surge, junction temperature derating above 25°C, unidirectional polarity marking, and compliance with J-STD-020 Level 1 moisture sensitivity for automated reflow assembly.
Technical Context
The SMAJ28C uses a glass-passivated silicon junction optimized for fast transient response (<1.0ps from 0V to VBR min) and low leakage (<1μA at VWM). Its single-die DO-214AC construction supports bidirectional variants only when suffixed with "CA" - the "C" suffix here denotes unidirectional configuration with cathode band marking.
It delivers 400W peak pulse power (10/1000μs waveform) up to 78V VWM; above that, rating drops to 300W. Thermal derating begins at TA > 25°C per Fig.2, with maximum junction temperature limited to +150°C and storage range from –55°C to +150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR min/max | 31.1 V / 38.0 V at IT = 1 mA - Ensures reliable turn-on margin above VWM with production tolerance |
| VC @ IPPM | 50.0 V at 8.0 A - Clamped voltage during 10/1000μs surge defines worst-case stress on downstream ICs |
| PPPM | 400 W (10/1000μs) - Peak surge energy handling capacity for automotive load dump and inductive switching events |
| IR @ VWM | <1 μA - Negligible leakage current preserves efficiency in high-impedance bias networks |
| Package | DO-214AC (SMA) - Standardized surface-mount outline compatible with JEDEC MS-013, 0.060g weight |
| Polarity | Cathode band marked - Unambiguous orientation for PCB layout and automated placement verification |
Pinout & Package
DO-214AC (SMA) package: molded epoxy case meeting UL 94V-0, matte tin-plated leads solderable per J-STD-002, polarity indicated by cathode band on one end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Low-side reference terminal | Connected to ground or low-voltage rail; forms return path during clamping conduction |
| Cathode | High-side surge input terminal | Connected to protected line (e.g., 24V rail); clamps to anode when transient exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| Fast response time | <1.0 ps - Enables suppression of nanosecond-scale ESD and switching spikes before sensitive circuitry reacts |
| Glass passivated junction | Stable VBR over life and temperature - Reduces parameter drift in industrial environments with thermal cycling |
| ISO 7637-2 compliance | Pulse 1/2a/2b/3a/3b validated - Meets automotive OEM requirements for battery-line transient immunity without external filtering |
| J-STD-020 Level 1 MSL | No floor life limitation - Supports unlimited dry pack storage and standard reflow profiles without baking |
| RoHS & halogen-free | IEC 61249-2-21 compliant - Enables use in consumer and industrial products requiring green material declarations |
Applications
| Automotive Infotainment Power Rail | Industrial PLC I/O Module |
|---|---|
Use Scenario: Protects 24V supply input of head unit MCU and display driver ICs against load dump and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between fused 24V rail and local LDO input, clamping within 50V to prevent LDO overvoltage failure. Use Value: With 50.0V VC and 400W PPPM, SMAJ28C limits stress on TPS7A47 LDO while surviving repeated ISO 7637-2 Pulse 5a events. |
Use Scenario: Shields digital input channel (24V sink type) from field-wiring induced surges in factory automation cabinets. IC Role / Device Role / Timing Role: Front-end protection device mounted directly at terminal block, shunting surge energy to chassis ground before optocoupler input. Use Value: 31.1–38.0V VBR ensures stable operation during normal 24V ±10% variation, while <1μA IR avoids false triggering of high-impedance sensing circuits. |
| LED Streetlight Driver Input | Telecom DC Power Interface |
Use Scenario: Guards primary-side bulk capacitor and PFC controller in outdoor LED drivers exposed to lightning-induced surges on AC mains. IC Role / Device Role / Timing Role: Secondary-stage TVS on DC bus after bridge rectifier, clamping residual transients escaping MOV-based front-end protection. Use Value: 8.0A IPPM and 50.0V VC allow coordination with upstream 14mm MOVs, ensuring staged energy absorption without overstressing downstream SiC MOSFET gate drivers. |
Use Scenario: Secures -48V telecom power feed entering remote radio head (RRH) enclosure against induced surges from nearby lightning strikes. IC Role / Device Role / Timing Role: Unidirectional clamp referenced to system ground, placed immediately after feed-through connector to minimize inductance before protection. Use Value: DO-214AC footprint enables compact layout with <1.5nH parasitic inductance, preserving sub-nanosecond response critical for -48V backplane integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ28A | Lower VBR range (31.1–34.4V), tighter tolerance; same VC (45.4V) and IPPM (8.8A) | Better suited for precision 24V systems where lower clamping onset reduces margin risk | Select SMAJ28A when tighter VBR distribution improves design margin over nominal 24V rails |
| SMBJ28C | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; 600W PPPM rating | Higher power handling allows longer surge duration or higher repetition rates in harsh environments | Choose SMBJ28C if board space permits and system requires >400W surge capability or extended thermal mass |
Compared with SMAJ28A and SMBJ28C, the SMAJ28C offers optimal balance of 400W surge rating, DO-214AC footprint compatibility, and cost-effective unidirectional protection for space-constrained 24V industrial and automotive modules.
Availability
SMAJ28C is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, LED streetlight drivers, and telecom DC power interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SMAJ28C 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, serving global industrial, automotive, and consumer markets since 1979.
The SMAJ series is part of TSC's transient voltage suppressor portfolio designed specifically for robust, standardized surface-mount surge protection in automotive and industrial power systems with stringent AEC-Q200 alignment.
FAQ
What is the clamping voltage of SMAJ28C under a 10/1000μs surge?
The SMAJ28C has a maximum clamping voltage (VC) of 50.0 V when subjected to an 8.0 A peak impulse current with a 10/1000μs waveform. This value is measured per standard test conditions in the datasheet and defines the upper voltage limit imposed on protected circuitry during transient events. The SMAJ28C maintains this clamping performance consistently across its qualified temperature range.
Is SMAJ28C unidirectional or bidirectional?
SMAJ28C is a unidirectional TVS diode, indicated by the "C" suffix and cathode band marking on the DO-214AC package. It conducts only during reverse-biased overvoltage events and blocks forward current like a standard rectifier. Bidirectional variants require the "CA" suffix (e.g., SMAJ28CA) and exhibit symmetrical clamping in both polarities.
Does SMAJ28C meet automotive transient standards?
Yes, SMAJ28C meets ISO 7637-2 requirements for Pulse 1, 2a, 2b, 3a, and 3b, making it suitable for 12V and 24V automotive power line protection. Its 400W peak pulse power rating, fast response time, and specified clamping behavior under standardized waveforms align with OEM immunity test plans for body control modules and infotainment systems.
What is the maximum junction temperature for SMAJ28C?
The SMAJ28C has a maximum junction temperature (TJ MAX) of +150°C, with an operating junction temperature range from –55°C to +150°C. Derating of peak pulse power begins above TA = 25°C per the published derating curve (Fig.2), and thermal design must ensure sustained power dissipation remains within steady-state limit of 1 W at ambient.
How is polarity identified on the SMAJ28C package?
Polarity on the SMAJ28C is indicated by a visible cathode band printed on the DO-214AC (SMA) package body - the banded end corresponds to the cathode terminal. This marking is consistent with JEDEC standards and enables correct orientation during automated placement and visual inspection. The anode is the opposite, unmarked end.
SMAJ28C 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:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ28C FAQ
1.How can I place an order for SMAJ28C through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28C 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 SMAJ28C reliable?
The price and inventory of SMAJ28C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28C is usually 5 days.
3.What payment methods are accepted for SMAJ28C?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28C transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28C?
SMAJ28C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28C 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 SMAJ28C?
For technical support, including SMAJ28C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28C requirements.
6.How does Aetrix verify that SMAJ28C is sourced from the original manufacturer or authorized distributors?
All SMAJ28C 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 SMAJ28C meets industry standards.
7.What is the process for return or replacement of SMAJ28C?
All SMAJ28C units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28C, 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 SMAJ28C part is unused and in its original packaging.
Return procedure for SMAJ28C:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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