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Vishay General Semiconductor - Diodes Division SMAJ18A-M3/5A
- Part No.:
- SMAJ18A-M3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18A-M3/5A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,564
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Product details
Overview
SMAJ18A-M3/5A from Vishay General Semiconductor is a unidirectional surface-mount Transient Voltage Suppressor (TVS) diode designed for primary overvoltage protection of sensitive ICs, MOSFETs, and signal lines in power rails and interface circuits. It features a 18 V stand-off voltage (VWM), 20.0–22.1 V breakdown voltage (VBR) at 1 mA, 29.2 V maximum clamping voltage (VC) at 13.7 A peak pulse current (IPPM), and 400 W peak pulse power rating with 10/1000 μs waveform.
For engineers reviewing the SMAJ18A-M3/5A datasheet, SMAJ18A-M3/5A pinout, SMAJ18A-M3/5A application, or SMAJ18A-M3/5A equivalent, key selection criteria include clamping performance under 13.7 A surge, thermal resistance (RθJA = 120 °C/W), unidirectional polarity marking, SMA (DO-214AC) package compatibility with automated placement, and halogen-free RoHS compliance per M3 suffix.
Technical Context
This TVS diode operates as a fast-acting shunt protector that remains high-impedance below 18 V and clamps transients above its breakdown threshold within picoseconds. Its glass-passivated junction ensures stable leakage (<1.0 μA at VWM) and repeatable avalanche behavior across temperature (-55 to +150 °C).
The device delivers 400 W peak pulse power handling on standard 0.2" × 0.2" copper pads, with derated capability (300 W) above 78 V. Its low incremental surge resistance and 0.092 %/°C VBR temperature coefficient support consistent clamping across operating conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse working voltage before significant leakage begins; defines safe operating rail margin. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed avalanche onset range; ensures reliable triggering above nominal supply. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage during 10/1000 μs surge; limits downstream stress to ≤29.2 V. |
| PPPM | 400 W - Peak transient energy absorption capacity with standard 10/1000 μs waveform. |
| ID @ VWM | ≤1.0 μA - Reverse leakage at 18 V; negligible power loss and signal integrity impact in standby. |
| RθJA | 120 °C/W - Junction-to-ambient thermal resistance on recommended PCB pad layout; informs derating above 25 °C. |
| Polarity | Unidirectional - Cathode marked by band; blocks forward conduction, clamps only reverse transients. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, MSL Level 1 (260 °C reflow peak). Dimensions: 4.50 mm × 2.79 mm × 2.29 mm (L × W × H); cathode band denotes terminal 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Transient current sink | Connected to protected line; conducts surge current to ground when V > VBR. |
| Anode | Reference return path | Typically tied to system ground or low-impedance return; completes clamping loop. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Supports robust protection against IEC 61000-4-5 Level 4 surges (4 kV/2 Ω) on 12–24 V rails. |
| 29.2 V clamping at 13.7 A | Limits voltage overshoot to safe levels for 3.3 V/5 V logic interfaces and gate drivers. |
| Glass passivated junction | Ensures long-term reliability and stable VBR drift <±5 % over lifetime and temperature. |
| MSL Level 1, 260 °C peak | Enables single-reflow assembly without moisture sensitivity concerns or baking requirements. |
| Halogen-free, RoHS-compliant (M3) | Meets environmental compliance mandates for industrial and automotive end equipment. |
Applications
| Industrial Motor Drives | Automotive Body Control Modules |
|---|---|
Use Scenario: Protection of gate driver ICs and microcontroller I/O pins against inductive kickback from relay and solenoid switching. IC Role / Device Role: Primary shunt clamp on 12 V power input and signal lines feeding MCU GPIOs. Use Value: Limits transient voltage to ≤29.2 V, preventing latch-up or oxide damage in 5 V-tolerant peripherals. |
Use Scenario: Safeguarding LIN bus transceivers and sensor supply rails from load dump and jump-start events. IC Role / Device Role: Secondary overvoltage clamp on 12 V battery-fed subsystems where primary regulation is present. Use Value: Withstands 400 W pulses without degradation, maintaining protection integrity across vehicle lifecycle. |
| Consumer Power Adapters | Telecom Interface Cards |
Use Scenario: Input-stage surge suppression on AC-DC adapter secondary-side 19 V output rails. IC Role / Device Role: Standoff-rated protector between DC output and downstream DC-DC converters. Use Value: 18 V VWM aligns with nominal 19 V output, allowing normal operation while clamping >22 V transients. |
Use Scenario: RS-485 transceiver port protection against ESD and lightning-induced surges on field wiring. IC Role / Device Role: Unidirectional clamp on VCC line and bidirectional variants on differential pairs (not this part). Use Value: Fast response time and low VC preserve signal integrity during multi-kV transients on telecom infrastructure links. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A-E3/5A | Same electrical specs; RoHS-compliant but contains brominated flame retardants (non-halogen-free). | Acceptable for commercial-grade non-automotive designs where halogen-free is not mandated. | Select SMAJ18A-M3/5A when halogen-free compliance is required per IPC-4101D or customer sustainability specs. |
| SMAJ18CA-M3/5A | Bidirectional variant; symmetric VBR (20.0–22.1 V) in both polarities; no polarity marking. | Suitable for AC-coupled or floating signal lines (e.g., USB D+/D−, Ethernet PHY) requiring dual-polarity clamping. | Choose SMAJ18CA-M3/5A only when protecting bidirectional signals; SMAJ18A-M3/5A is optimal for DC rails with defined ground reference. |
Compared with SMAJ18A-E3/5A, the M3 version adds halogen-free construction without sacrificing electrical performance; versus SMAJ18CA-M3/5A, the unidirectional SMAJ18A-M3/5A provides lower capacitance and avoids unnecessary bidirectional conduction on grounded DC lines.
Availability
SMAJ18A-M3/5A is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, and consumer power adapters requiring stable component supply with halogen-free compliance and AEC-Q101-qualified alternatives.
Supply support for SMAJ18A-M3/5A 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
Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, MOSFETs, and protection devices with emphasis on reliability, power efficiency, and automotive qualification.
The SMAJ series targets board-level transient suppression in space-constrained applications, delivering standardized 400 W surge capability in the compact SMA package for cost-sensitive, high-volume industrial and automotive systems.
FAQ
What is the clamping voltage of SMAJ18A-M3/5A at its rated peak pulse current?
The SMAJ18A-M3/5A exhibits a maximum clamping voltage (VC) of 29.2 V when subjected to its rated peak pulse current (IPPM) of 13.7 A under the standard 10/1000 μs waveform. This value is measured per JEDEC test conditions and guarantees that downstream circuitry sees no more than 29.2 V during such transient events, making SMAJ18A-M3/5A suitable for protecting 24 V systems with 5 V or 3.3 V logic interfaces.
Is SMAJ18A-M3/5A suitable for automotive applications?
SMAJ18A-M3/5A itself is commercial-grade (M3 suffix), but Vishay offers the AEC-Q101-qualified variant SMAJ18A-HM3/5A for automotive use. The SMAJ18A-M3/5A shares identical electrical characteristics and package dimensions, enabling drop-in qualification upgrades. For production automotive designs, specify the HM3 version; SMAJ18A-M3/5A remains appropriate for prototyping, industrial, or consumer applications where AEC-Q101 is not mandated.
How does the M3 suffix differ from E3 in SMAJ18A-M3/5A?
The M3 suffix indicates halogen-free, RoHS-compliant construction using bromine-free flame retardants in the molding compound, whereas E3 is RoHS-compliant but may contain regulated halogens. Both meet JESD201 Class 2 whisker resistance and J-STD-020 MSL Level 1. SMAJ18A-M3/5A satisfies stricter environmental requirements such as IPC-4101D and major OEM sustainability directives, while maintaining identical electrical performance and thermal behavior as SMAJ18A-E3/5A.
What is the thermal resistance of SMAJ18A-M3/5A, and how does it affect layout?
SMAJ18A-M3/5A has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on the minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes standard FR-4 PCB with no internal planes. To maintain safe junction temperatures under repetitive surges, designers must ensure adequate copper area and avoid excessive ambient temperature rise; doubling pad size reduces RθJA by ~15–20 %, directly improving power handling margin for SMAJ18A-M3/5A.
Can SMAJ18A-M3/5A be used in place of SMAJ18CA-M3/5A?
No - SMAJ18A-M3/5A is unidirectional and requires correct polarity orientation (cathode toward protected line), while SMAJ18CA-M3/5A is bidirectional with no polarity marking and symmetric clamping in both directions. Substituting SMAJ18A-M3/5A for SMAJ18CA-M3/5A on AC or floating differential lines risks failure to clamp positive transients. SMAJ18A-M3/5A is appropriate only for DC rails with defined ground reference; always verify signal topology before selecting SMAJ18A-M3/5A.
SMAJ18A-M3/5A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AC, SMA
- Series:
- TransZorb®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- 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)
SMAJ18A-M3/5A FAQ
1.How can I place an order for SMAJ18A-M3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18A-M3/5A 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-M3/5A reliable?
The price and inventory of SMAJ18A-M3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18A-M3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ18A-M3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18A-M3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18A-M3/5A?
SMAJ18A-M3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18A-M3/5A 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-M3/5A?
For technical support, including SMAJ18A-M3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18A-M3/5A requirements.
6.How does Aetrix verify that SMAJ18A-M3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ18A-M3/5A 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-M3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ18A-M3/5A?
All SMAJ18A-M3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18A-M3/5A, 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-M3/5A part is unused and in its original packaging.
Return procedure for SMAJ18A-M3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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