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Diodes Incorporated SMAJ18A-13
- Part No.:
- SMAJ18A-13
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18A-13.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:9,363
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Product details
Overview
SMAJ18A-13 from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power rails and signal lines. It features a 18 V reverse standoff voltage (VRWM), 20.0–22.1 V breakdown voltage (VBR) at 1.0 mA, 29.2 V maximum clamping voltage (VC) at 13.7 A peak pulse current (IPP), and operates from –55 °C to +150 °C junction temperature.
For engineers reviewing the SMAJ18A-13 datasheet, SMAJ18A-13 pinout, SMAJ18A-13 application, or SMAJ18A-13 equivalent, key selection criteria include clamping performance under 8.3 ms surge, unidirectional polarity for DC-biased lines, SMA package thermal and mechanical compatibility, and RoHS-compliant lead-free plating per JEDEC standards.
Technical Context
The SMAJ18A-13 uses a glass-passivated silicon junction to achieve fast response time (<1 ps) and stable clamping during transient events such as ESD, lightning-induced surges, and inductive switching spikes. Its unidirectional configuration enables integration into polarized DC circuits without reverse leakage concerns beyond 5 µA at VRWM.
It is rated for 400 W peak pulse power (10/1000 µs waveform), supports 40 A non-repetitive forward surge current (8.3 ms half-sine), and maintains steady-state dissipation of 1.0 W at TL = 75 °C. Clamping occurs at ≤29.2 V when subjected to 13.7 A IPP, ensuring downstream ICs remain within safe operating voltage margins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400 W - sustains single high-energy transients without failure (10/1000 µs waveform) |
| Reverse Standoff Voltage (VRWM) | 18 V - maximum continuous DC voltage before significant leakage; sets operating rail margin |
| Breakdown Voltage (VBR) | 20.0–22.1 V @ 1.0 mA - precise conduction onset threshold for reliable clamping activation |
| Max Clamping Voltage (VC) | 29.2 V @ 13.7 A IPP - limits protected circuit voltage during worst-case surge |
| Junction Temp Range | –55 °C to +150 °C - supports automotive under-hood, industrial control, and outdoor power applications |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline with 5.59 mm max body length and 2.30 mm max terminal width |
Pinout & Package
SMAJ18A-13 is housed in the SMA (DO-214AC) package: molded plastic case, UL 94V-0 flammability rating, cathode band polarity indicator, and matte tin lead finish compliant with RoHS and JEDEC solderability standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point in forward bias; connected to protected line ground or low-side return | Completes clamping path during positive transients on cathode-connected rail |
| Cathode | Current exit point in forward bias; connected to protected supply rail or signal line | Defines unidirectional conduction direction and establishes VRWM reference |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated die | Ensures stable VBR tolerance and long-term reliability under thermal cycling and humidity stress |
| 400 W peak pulse rating | Provides robust protection against IEC 61000-4-5 Level 4 (4 kV) surges in industrial power inputs |
| Fast response time | Sub-nanosecond turn-on prevents voltage overshoot before clamping engages |
| Lead-free / RoHS-compliant | Meets global environmental compliance requirements without compromising solder joint integrity |
Applications
| Industrial PLC I/O Protection | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Protecting 24 V DC digital input channels from load dump and relay coil flyback. IC Role / Device Role / Timing Role: Primary shunt TVS placed between input pin and chassis ground. Use Value: Clamps transients to ≤29.2 V, keeping microcontroller GPIO within absolute maximum ratings. | Use Scenario: Safeguarding LIN bus transceiver power pins against battery voltage spikes. IC Role / Device Role / Timing Role: Unidirectional clamp on VCC rail upstream of regulator input. Use Value: Prevents regulator latch-up or internal ESD diode failure during 12 V system surges. |
| Telecom Power Feeds | Smart Meter DC Power Input |
Use Scenario: Overvoltage protection on 48 V PoE-derived DC supply lines. IC Role / Device Role / Timing Role: First-stage transient suppressor before DC-DC converter input. Use Value: Absorbs up to 400 W surge energy while maintaining <5 µA leakage at nominal 48 V derated operation. | Use Scenario: Securing 3.3 V or 5 V auxiliary supply derived from mains-connected SMPS. IC Role / Device Role / Timing Role: Secondary clamp on low-voltage rail after primary MOV/fuse stage. Use Value: Adds precision clamping layer with tight VC tolerance to protect metrology ICs and RTCs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CA-13 | Bi-directional version; symmetric clamping for AC-coupled or floating signal lines | Required where bidirectional surges occur (e.g., RS-485, CAN bus); not suitable for polarized DC rails | Select only if circuit lacks defined polarity or handles AC transients |
| SMBJ18A-13 | Same electrical specs but SMB (DO-214AA) package; 50% larger footprint and higher thermal mass | Better power handling margin in high-ambient environments; requires PCB layout change | Choose when board space allows and thermal derating above 75 °C is critical |
Compared with SMAJ18CA-13 and SMBJ18A-13, SMAJ18A-13 offers optimal balance of compact SMA footprint, unidirectional DC rail compatibility, and verified 400 W surge capability-making it preferred for space-constrained, single-polarity industrial and automotive power interfaces.
Availability
SMAJ18A-13 is available at Aetrix Electronics and suitable for industrial PLC I/O protection, automotive body control modules, and smart meter DC power inputs requiring stable component supply across extended production lifecycles.
Supply support for SMAJ18A-13 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.
The SMAJ series belongs to Diodes' transient voltage suppression portfolio, engineered specifically for high-reliability, surface-mount overvoltage protection in harsh-environment power and signal interfaces.
FAQ
What is the polarity configuration of SMAJ18A-13?
SMAJ18A-13 is a unidirectional TVS diode, with cathode marked by a band on the SMA package body. It conducts only when the cathode is at a higher potential than the anode, making it suitable for DC-biased protection where polarity is fixed and reverse leakage must be minimized below 5 µA at 18 V.
Can SMAJ18A-13 be used in AC signal lines?
No-SMAJ18A-13 is unidirectional and unsuitable for AC or bidirectional signal paths. For such applications, the bi-directional variant SMAJ18CA-13 must be used, which clamps symmetrically above and below ground and has no polarity marking.
What is the maximum allowable mounting temperature during reflow?
The SMAJ18A-13 is qualified for standard lead-free reflow per J-STD-020C, with peak temperature up to 260 °C for ≤30 seconds. Its UL 94V-0 mold compound and matte tin terminations ensure mechanical integrity and wetting performance under IPC-A-610 Class 2/3 conditions.
How does its clamping performance compare to SMAJ15A-13?
SMAJ18A-13 clamps at 29.2 V (13.7 A), while SMAJ15A-13 clamps at 24.4 V (16.4 A). The higher VRWM of SMAJ18A-13 trades lower clamping voltage for improved immunity to nuisance triggering on 18 V nominal rails, making it more appropriate for 24 V systems with tighter tolerance margins.
SMAJ18A-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20V
- Voltage - Clamping (Max) @ Ipp:
- 29.2V
- Current - Peak Pulse (10/1000µs):
- 13.7A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- Yes
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMAJ)
SMAJ18A-13 FAQ
1.How can I place an order for SMAJ18A-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18A-13 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 SMAJ18A-13 reliable?
The price and inventory of SMAJ18A-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18A-13 is usually 5 days.
3.What payment methods are accepted for SMAJ18A-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18A-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18A-13?
SMAJ18A-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18A-13 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 SMAJ18A-13?
For technical support, including SMAJ18A-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18A-13 requirements.
6.How does Aetrix verify that SMAJ18A-13 is sourced from the original manufacturer or authorized distributors?
All SMAJ18A-13 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 SMAJ18A-13 meets industry standards.
7.What is the process for return or replacement of SMAJ18A-13?
All SMAJ18A-13 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18A-13, 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 SMAJ18A-13 part is unused and in its original packaging.
Return procedure for SMAJ18A-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ18A-13 Tags
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ESD9B5.0ST5G
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