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Taiwan Semiconductor Corporation SMAJ28CA
- Part No.:
- SMAJ28CA
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ28CA.pdf
- Description:
- TVS DIODE 28VWM 45.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,224
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Product details
Overview
SMAJ28CA from Taiwan Semiconductor is a bidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for robust overvoltage protection in DC power rails. It features a 28 V working stand-off voltage (VWM), 31.1–34.4 V breakdown voltage (VBR @ 1 mA), and clamps to ≤45.4 V at 8.8 A peak impulse current under 10/1000 µs waveform - enabling reliable surge suppression in automotive and industrial power supplies.
For engineers reviewing the SMAJ28CA datasheet, SMAJ28CA pinout, SMAJ28CA application, or SMAJ28CA equivalent, key selection criteria include bidirectional clamping capability, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, 400 W peak pulse power rating (10/1000 µs), low leakage (<1 µA @ 28 V), and DO-214AC thermal and mechanical compatibility with automated SMT assembly.
Technical Context
The SMAJ28CA implements a silicon avalanche junction structure with glass passivation, delivering sub-1 ps response time from 0 V to VBR min and stable clamping across -55 °C to +150 °C operating junction temperature. Its bidirectional configuration eliminates polarity sensitivity, supporting symmetric transient suppression on AC-coupled or floating lines.
It meets ISO 7637-2 for automotive load-dump and inductive-switching transients, with 400 W peak pulse power (derated above 25 °C) and 1 W steady-state dissipation. The device exhibits <1 µA reverse leakage at rated VWM, ensuring minimal standby power loss in always-on systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 28 V - Maximum continuous reverse voltage before significant leakage; defines safe operating margin below clamping threshold. |
| VBR @ IT = 1 mA | 31.1–34.4 V - Measured breakdown range confirming consistent avalanche initiation across production lot. |
| VC @ IPPM = 8.8 A | ≤45.4 V - Clamped voltage during 10/1000 µs surge; determines maximum stress imposed on downstream circuitry. |
| PPPM | 400 W - Peak pulse power handling per 10/1000 µs waveform; enables protection against high-energy transients like ISO 7637-2 Pulse 5a. |
| IR @ VWM | <1 µA - Reverse leakage at stand-off voltage; ensures negligible quiescent current in battery-backed or low-power systems. |
| Junction Temp Range | -55 °C to +150 °C - Enables deployment in under-hood automotive, industrial motor drives, and outdoor power electronics. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with 0.060 g mass, UL 94V-0 molding, and matte tin-plated leads compliant with J-STD-002 solderability. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with two coplanar leads; cathode band marking denotes polarity for unidirectional variants only - SMAJ28CA is bidirectional and has no functional polarity marking. Leads are matte tin-plated, RoHS-compliant, and halogen-free per IEC 61249-2-21.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Bidirectional avalanche junction terminals | No functional polarity - either terminal serves as anode or cathode depending on transient polarity; enables placement without orientation check. |
| Case / Body | Non-conductive encapsulation | UL 94V-0 rated thermoset compound provides flame resistance and mechanical stability during reflow and operation. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC lines, differential buses, or floating DC rails without polarity constraints. |
| 400 W peak pulse power (10/1000 µs) | Withstands high-energy transients such as automotive load dump (ISO 7637-2 Pulse 5a) without degradation. |
| Sub-1 ps response time | Clamps before sensitive ICs experience overvoltage stress - critical for protecting CAN, LIN, and MCU I/O pins. |
| Moisture sensitivity level 1 | Zero bake requirement prior to reflow; supports standard SMT assembly without special handling. |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Validated for automotive ECU, body control module, and infotainment system power rail protection. |
Applications
| Automotive Power Rail Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting 24 V battery-fed ECUs against load dump and alternator switching transients. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC/DC controller and LDO regulators. Use Value: Limits transient voltage to ≤45.4 V, preventing damage to 36 V-rated input stages while maintaining >28 V nominal operation. |
Use Scenario: Safeguarding isolated 48 V-to-12 V DC/DC converters in factory automation equipment. IC Role / Device Role / Timing Role: Secondary-side TVS on output rail to absorb reflected surges and cross-regulation spikes. Use Value: Clamps fast-rising transients (<1 ps) before they propagate to connected PLC I/O modules or sensors. |
| LED Driver Overvoltage Suppression | Smart Meter Power Supply Input |
Use Scenario: Shielding constant-current LED drivers from line surges in streetlight and tunnel lighting systems. IC Role / Device Role / Timing Role: Parallel-connected TVS across driver input capacitor to shunt surge energy away from controller IC. Use Value: 400 W rating handles repeated lightning-induced surges; bidirectional design accommodates AC-coupled dimming signals. |
Use Scenario: Securing AC/DC adapter input stage in utility smart meters exposed to grid transients. IC Role / Device Role / Timing Role: First-line transient suppressor after bridge rectifier, before bulk capacitor and PFC stage. Use Value: ≤1 µA leakage preserves meter accuracy during low-load conditions; DO-214AC footprint fits constrained meter PCB layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ28CA (Bourns) | Same VWM (28 V), higher PPPM (600 W), larger SMB package (DO-214AA). | Requires PCB layout change; better suited for higher-energy transients where space permits. | Select when surge energy exceeds 400 W or thermal margin is constrained by ambient temperature. |
| P6SMB28CA (Littelfuse) | Identical VWM/VBR/VC specs, same DO-214AC package, but rated at 600 W PPPM. | Drop-in replacement in footprint; higher power rating allows longer surge duration tolerance. | Choose for designs requiring extended surge immunity without changing board layout or assembly process. |
Compared with SMBJ28CA and P6SMB28CA, the SMAJ28CA offers optimal balance of 400 W surge capacity, DO-214AC compactness, and cost efficiency for mid-tier automotive and industrial applications where strict 600 W headroom is not required.
Availability
SMAJ28CA is available at Aetrix Electronics and suitable for automotive power rail protection, industrial DC/DC converter inputs, and LED driver overvoltage suppression requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for SMAJ28CA 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs, with global distribution and AEC-Q101 qualified product lines.
The SMAJ series was developed specifically for surface-mount transient suppression in automotive and industrial environments, emphasizing ISO 7637-2 compliance, high reliability under thermal cycling, and compatibility with high-speed SMT assembly.
FAQ
What is the clamping voltage of SMAJ28CA at its rated peak pulse current?
The SMAJ28CA clamps to a maximum of 45.4 V when subjected to its specified peak impulse current of 8.8 A under the standard 10/1000 µs waveform. This value is measured per JEDEC test conditions and guarantees predictable overvoltage limiting for downstream components such as DC/DC controllers and microcontrollers in the protected circuit.
Is SMAJ28CA unidirectional or bidirectional, and how does that affect PCB layout?
SMAJ28CA is a bidirectional TVS diode, meaning it provides symmetrical clamping for both positive and negative transients without polarity dependence. Unlike unidirectional variants, it has no cathode band marking and can be placed in either orientation on the PCB - eliminating orientation verification during automated assembly and simplifying layout for differential or floating signal lines.
Does SMAJ28CA meet automotive transient immunity standards?
Yes, SMAJ28CA meets ISO 7637-2 requirements for Pulses 1, 2a, 2b, 3a, and 3b, making it suitable for use in automotive electronic control units, body electronics, and infotainment systems. Its 400 W peak pulse power rating and fast response time ensure robust protection against common vehicle electrical disturbances including load dump and inductive switching.
What is the maximum operating temperature for SMAJ28CA, and how does derating work above 25°C?
The SMAJ28CA has a maximum junction temperature of +150 °C and operates from -55 °C to +150 °C. Its peak pulse power rating of 400 W is specified at TA = 25 °C and must be linearly derated above that ambient temperature per the manufacturer's pulse derating curve (Fig. 2 in U2102 datasheet), reaching ~240 W at 85 °C ambient.
Can SMAJ28CA be used in place of SMAJ28A, and what is the key difference?
No - SMAJ28CA and SMAJ28A are distinct variants: SMAJ28CA is bidirectional (CA suffix), while SMAJ28A is unidirectional (A suffix). Their VBR ranges differ (SMAJ28CA: 31.1–34.4 V; SMAJ28A: 31.1–34.4 V), but SMAJ28A requires correct cathode orientation and only clamps in reverse bias. Substituting one for the other without verifying circuit topology and polarity will result in improper or failed protection.
SMAJ28CA 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:
- 45.4V
- Current - Peak Pulse (10/1000µs):
- 8.8A
- 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)
SMAJ28CA FAQ
1.How can I place an order for SMAJ28CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ28CA 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 reliable?
The price and inventory of SMAJ28CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ28CA is usually 5 days.
3.What payment methods are accepted for SMAJ28CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ28CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ28CA?
SMAJ28CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ28CA 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?
For technical support, including SMAJ28CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ28CA requirements.
6.How does Aetrix verify that SMAJ28CA is sourced from the original manufacturer or authorized distributors?
All SMAJ28CA 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 meets industry standards.
7.What is the process for return or replacement of SMAJ28CA?
All SMAJ28CA units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ28CA, 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 part is unused and in its original packaging.
Return procedure for SMAJ28CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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