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Diodes Incorporated SMAJ18CA-13
- Part No.:
- SMAJ18CA-13
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CA-13.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:6,207
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Product details
Overview
SMAJ18CA-13 from Diodes Incorporated is a 400W bi-directional transient voltage suppressor (TVS) diode in SMA package, designed for clamping ESD and surge transients on data lines and power rails. It features a 18V reverse standoff voltage (VRWM), 20.0–22.1V breakdown voltage (VBR @ 1mA), 29.2V max clamping voltage at 13.7A peak pulse current, and operates from –55°C to +150°C - used in industrial Ethernet port protection and automotive body control module I/O interfaces.
For engineers reviewing the SMAJ18CA-13 datasheet, SMAJ18CA-13 pinout, SMAJ18CA-13 application, or SMAJ18CA-13 equivalent, key selection criteria include clamping voltage margin vs. protected IC VCC, bidirectional symmetry for AC-coupled signal lines, JEDEC-compliant 8.3ms surge rating, and RoHS-compliant matte tin termination compatibility with lead-free reflow profiles.
Technical Context
This bi-directional TVS diode uses glass-passivated junction construction to achieve fast response time (<1 ps) and stable clamping under repetitive transients. Its symmetrical I-V curve enables protection of AC signals without polarity concerns, and it complies with IEC 61000-4-2 (±30kV contact) and IEC 61000-4-4 (±4kV EFT) standards when properly laid out.
The device is rated for 400W non-repetitive peak pulse power (8.3ms half-sine), derates linearly above 25°C ambient, and maintains <5µA reverse leakage at VRWM - critical for low-power sensor interface integrity and battery-backed system standby current budgets.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400W - sustains single 8.3ms surge events per JEDEC method without degradation |
| Reverse Standoff Voltage (VRWM) | 18V - maximum continuous DC or RMS voltage before significant leakage begins |
| Breakdown Voltage (VBR) | 20.0–22.1V @ 1mA - defines onset of avalanche conduction during overvoltage |
| Max Clamping Voltage (VC) | 29.2V @ 13.7A IPP - upper limit of voltage seen by downstream circuit during worst-case surge |
| Operating Temperature | –55°C to +150°C - supports under-hood automotive and industrial control cabinet deployment |
| Package | SMA (DO-214AC) - surface-mount footprint compatible with IPC-7351B standard land pattern |
| RoHS Compliance | Lead-free matte tin finish - meets EU Directive 2011/65/EU Annex exemptions for high-temp solder |
Pinout & Package
SMA (DO-214AC) package: molded plastic case, UL 94V-0 rated, cathode band omitted (bi-directional), terminals solderable per MIL-STD-202 Method 208.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Transient conduction path | Bi-directional terminals - either end serves as input/output; no polarity dependency in AC or differential line protection |
| Case / Body | Thermal & mechanical reference | Non-electrical; provides thermal path to PCB copper and mechanical mounting stability |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated die | Enables stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure |
| 400W peak pulse rating | Clamps 13.7A surges at ≤29.2V - sufficient for Level 4 IEC 61000-4-5 (1kV/2Ω) on 24V systems |
| Bidirectional configuration | Protects AC-coupled interfaces (e.g., RS-485, CAN FD, audio lines) without external polarity management |
| Low clamping ratio (VC/VBR ≈ 1.45) | Minimizes overvoltage stress on protected ICs compared to higher-ratio alternatives |
Applications
| Industrial Ethernet Port Protection | Automotive Body Control Module I/O |
|---|---|
Use Scenario: Protecting RJ45 PHY interface against ESD and lightning-induced surges in factory automation gateways. IC Role / Device Role / Timing Role: Bidirectional TVS placed across differential pairs (e.g., TX+/TX–) to clamp common-mode transients before signal conditioning ICs. Use Value: Maintains signal integrity below 29.2V clamping while surviving ±30kV contact discharge - avoids PHY latch-up or damage. | Use Scenario: Safeguarding LIN bus pins and sensor inputs in door module ECUs exposed to load dump and jump-start transients. IC Role / Device Role / Timing Role: Parallel-connected TVS on each LIN line and analog sensor supply rail to shunt energy away from microcontroller GPIOs. Use Value: Withstands 13.7A pulses at 29.2V and operates up to +150°C - ensures functional safety compliance in engine bay-adjacent modules. |
| Smart Meter Communication Interface | POS Terminal Serial Port Protection |
Use Scenario: Shielding RS-485 communication lines between utility meters and concentrators from induced surges on long outdoor runs. IC Role / Device Role / Timing Role: Bi-directional clamping device mounted at connector entry point to absorb differential and common-mode transients. Use Value: Symmetrical clamping ensures equal protection for both polarities of RS-485 signaling - preserves data integrity during 4kV EFT bursts. | Use Scenario: Securing RS-232 and USB D+/D– lines in retail payment terminals against user-handling ESD and AC mains coupling. IC Role / Device Role / Timing Role: Low-capacitance TVS placed directly at board edge connectors to minimize stub length and preserve signal rise time. Use Value: Sub-100pF junction capacitance at 0V bias prevents signal distortion on 115.2kbps serial links - verified per Figure 2 in datasheet. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A-13 | Unidirectional; 29.2V VC same, but only clamps positive transients - requires external polarity handling for AC signals | Restricted to DC-biased lines (e.g., 5V/12V supply rails); unsuitable for RS-485 or CAN | Select only if protecting unidirectional power or logic lines where polarity is fixed and cost is prioritized |
| SMBJ18CA-13 | Same electrical specs but SMB (DO-214AA) package - 2.5mm wider body, higher thermal mass, 600W rating | Better surge endurance in space-constrained designs needing higher PPK margin; larger footprint | Choose when board layout allows SMB size and system-level surge testing exceeds 400W requirements |
Compared with SMAJ18A-13, SMAJ18CA-13 enables polarity-agnostic protection without additional diodes; versus SMBJ18CA-13, it trades 200W peak power headroom for 1.2mm smaller width - optimal for dense industrial PCBs with validated 400W surge margins.
Availability
SMAJ18CA-13 is available at Aetrix Electronics and suitable for industrial Ethernet port protection, automotive body control module I/O, smart meter communication interfaces, and POS terminal serial port protection requiring stable component supply across multi-year production cycles.
Supply support for SMAJ18CA-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 centers across Asia and manufacturing in China, Taiwan, and the U.S.
The SMAJ series belongs to Diodes' transient suppression product line, engineered specifically for robust, surface-mount surge protection in harsh environments - emphasizing tight VBR tolerance, low clamping ratio, and extended temperature operation.
FAQ
What is the maximum clamping voltage of SMAJ18CA-13 and under what test condition?
The maximum clamping voltage is 29.2V, measured at 13.7A peak pulse current (IPP) using an 8.3ms single half-sine waveform per JEDEC standards. This value represents the highest voltage imposed on protected circuitry during worst-case surge events and is guaranteed across the full operating temperature range.
Is SMAJ18CA-13 suitable for protecting high-speed data lines like USB 2.0 or HDMI?
No - its typical junction capacitance is ~100pF at 0V (per Figure 2), which exceeds the <5pF requirement for USB 2.0 full-speed signaling and would severely degrade signal integrity. It is intended for lower-speed interfaces such as RS-232, RS-485, LIN, and analog sensor lines where bandwidth is not critical.
Does SMAJ18CA-13 require a heatsink for continuous operation?
No - it is rated for 1.0W steady-state power dissipation at 75°C lead temperature (TL) and relies on PCB copper area for thermal management. No external heatsink is needed unless operating continuously near PM(AV) limit in high-ambient environments; thermal derating curves are provided in Figure 6 of the datasheet.
How does the "C" suffix in SMAJ18CA-13 affect its marking and polarity identification?
The "C" denotes bi-directional functionality, and per datasheet Note 5, bi-directional devices omit the cathode band marking. The part is marked with "IT" (see Page 2 table), and visual inspection reveals no polarity indicator - confirming symmetrical terminal behavior essential for AC-coupled line protection.
SMAJ18CA-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:
- -
- Bidirectional Channels:
- 2
- 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)
SMAJ18CA-13 FAQ
1.How can I place an order for SMAJ18CA-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CA-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 SMAJ18CA-13 reliable?
The price and inventory of SMAJ18CA-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CA-13 is usually 5 days.
3.What payment methods are accepted for SMAJ18CA-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CA-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CA-13?
SMAJ18CA-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CA-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 SMAJ18CA-13?
For technical support, including SMAJ18CA-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CA-13 requirements.
6.How does Aetrix verify that SMAJ18CA-13 is sourced from the original manufacturer or authorized distributors?
All SMAJ18CA-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 SMAJ18CA-13 meets industry standards.
7.What is the process for return or replacement of SMAJ18CA-13?
All SMAJ18CA-13 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CA-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 SMAJ18CA-13 part is unused and in its original packaging.
Return procedure for SMAJ18CA-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ18CA-13 Tags
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ESD9B5.0ST5G
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