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Vishay General Semiconductor - Diodes Division SMAJ18A-M3/61
- Part No.:
- SMAJ18A-M3/61
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18A-M3/61.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,220
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Product details
Overview
SMAJ18A-M3/61 from Vishay General Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in power and signal lines. 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 (10/1000 μs waveform), making it suitable for protecting MOSFETs, ICs, and sensor interfaces against inductive switching transients and ESD in industrial and automotive electronics.
For engineers reviewing the SMAJ18A-M3/61 datasheet, SMAJ18A-M3/61 pinout, SMAJ18A-M3/61 application, or SMAJ18A-M3/61 equivalent, key selection criteria include its unidirectional polarity, SMA (DO-214AC) package with cathode band marking, 1.0 μA max reverse leakage at VWM, -55 °C to +150 °C operating junction temperature, and halogen-free RoHS-compliant construction per M3 suffix.
Technical Context
The SMAJ18A-M3/61 operates as a clamping-type TVS diode using an avalanche breakdown mechanism to limit transient voltages. Its low incremental surge resistance and fast response time (<1 ns) enable effective suppression of fast-rising transients such as ESD (IEC 61000-4-2) and inductive load spikes.
It is rated for 400 W peak pulse power (10/1000 μs) up to 78 V, derating to 300 W above that threshold, and supports repetitive surge events at 0.01 % duty cycle. Thermal performance is defined by RθJA = 120 °C/W and RθJL = 30 °C/W, with mounting on 0.2" × 0.2" copper pads per specification.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse working voltage before clamping initiates; defines safe operating margin below breakdown. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed avalanche breakdown range; ensures predictable turn-on under transient stress. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage during 10/1000 μs surge; determines protected circuit's maximum transient exposure. |
| PPPM | 400 W (≤78 V) - Peak pulse power handling capability; defines energy absorption capacity for standard lightning/surge waveforms. |
| ID @ VWM | 1.0 μA max - Reverse leakage current at stand-off voltage; critical for low-power sensor and battery-backed circuits. |
| TJ max | +150 °C - Maximum junction temperature; enables operation in under-hood automotive and high-ambient industrial environments. |
| Package | SMA (DO-214AC) - Surface-mount package with 2.54 mm lead pitch; compatible with automated placement and reflow soldering. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, MSL Level 1 (JEDEC J-STD-020), 260 °C peak reflow profile. Polarity indicated by cathode band on unidirectional devices.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path); conducts during forward surge (IFSM = 40 A). |
| Cathode | Reverse-biased clamping terminal | Marked with band; connected to protected line (e.g., 12 V rail or signal input); avalanches into conduction when V > VBR. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power (10/1000 μs) | Enables reliable suppression of IEC 61000-4-5 Level 3 surges (1 kV/2 Ω) on 12 V systems without degradation. |
| Low clamping ratio (VC/VBR ≈ 1.4) | Minimizes overvoltage stress on downstream ICs-e.g., keeps microcontroller I/O pins below absolute maximum ratings during transients. |
| Halogen-free, RoHS-compliant (M3 suffix) | Meets environmental compliance requirements for automotive and industrial OEMs without compromising surge robustness. |
| Fast response time (<1 ns) | Clamps transients before sensitive logic or analog circuitry can be damaged-critical for high-speed sensor interfaces and CAN bus protection. |
| AEC-Q101 qualified variants available | Supports automotive qualification pathways; SMAJ18A-M3/61 itself is commercial-grade but shares identical die and package design with qualified versions. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 12 V power inputs of body control modules (BCM) and infotainment head units from load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS clamping device placed between power rail and ground, activated only during positive overvoltage events. Use Value: Limits transient voltage to ≤29.2 V, preventing latch-up or permanent damage to 36 V-rated DC-DC converters and LDOs downstream. |
Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loop) of pressure sensors in factory automation PLCs. IC Role / Device Role / Timing Role: Standoff-mode protector on signal line, absorbing ESD strikes and cable discharge events without affecting baseline accuracy. Use Value: 1.0 μA leakage at 18 V ensures minimal offset error in precision current-sense circuits; 29.2 V clamping prevents op-amp saturation. |
| Consumer Device USB Port Protection | MOSFET Gate Driver Transient Suppression |
|
Use Scenario: Safeguarding USB VBUS and D+/D− lines in portable monitors and docking stations against hot-plug ESD and cable-induced surges. IC Role / Device Role / Timing Role: Discrete TVS array component placed at connector entry point, shunting transients to chassis ground. Use Value: Fast <1 ns response captures sub-nanosecond ESD pulses (IEC 61000-4-2 ±15 kV contact); SMA footprint allows compact layout near connector. |
Use Scenario: Protecting high-side N-channel MOSFET gate drivers in motor control inverters from Miller-induced voltage spikes during switching. IC Role / Device Role / Timing Role: Clamping diode across gate-source terminals to clamp dv/dt-induced overshoot and prevent unintended turn-on. Use Value: 20–22.1 V VBR aligns with typical 15–20 V gate drive rails; 29.2 V VC ensures gate oxide remains within safe voltage limits (±20 V). |
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-E3/61 | Same electrical specs and package; RoHS-compliant but not halogen-free (E3 vs. M3). | Preferred for commercial-grade applications where halogen-free requirement is not mandated. | Select SMAJ18A-E3/61 if environmental compliance only requires RoHS, not halogen-free materials. |
| SMAJ18CA-M3/61 | Bidirectional variant; symmetric VBR (20.0–22.1 V) in both polarities; same VWM, VC, and PPPM. | Required for AC-coupled or dual-polarity signal lines (e.g., RS-485, CAN bus) where negative transients must also be clamped. | Choose SMAJ18CA-M3/61 only when bidirectional protection is needed; unidirectional SMAJ18A-M3/61 offers lower leakage in DC applications. |
Compared with SMAJ18A-E3/61, the SMAJ18A-M3/61 provides halogen-free construction for stricter environmental programs, while SMAJ18CA-M3/61 adds bidirectional clamping at the cost of slightly higher leakage in DC bias conditions-making SMAJ18A-M3/61 optimal for cost-sensitive, single-polarity 12–24 V rail protection.
Availability
SMAJ18A-M3/61 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial sensor interface hardening, consumer USB port safeguarding, and MOSFET gate driver transient suppression requiring stable component supply and traceable sourcing.
Supply support for SMAJ18A-M3/61 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, TVS devices, and optoelectronics with emphasis on reliability, efficiency, and application-specific performance.
The SMAJ series was developed for high-energy transient suppression in space-constrained surface-mount designs across automotive, industrial, and computing systems-prioritizing low clamping voltage, repeatable surge endurance, and automated assembly compatibility.
FAQ
What is the maximum clamping voltage of the SMAJ18A-M3/61 under a 10/1000 μs surge?
The SMAJ18A-M3/61 has a maximum clamping voltage (VC) of 29.2 V at 13.7 A peak pulse current (IPPM), measured with a 10/1000 μs waveform. This value is guaranteed per Vishay's datasheet (Document Number: 88390, Rev. 09-Jan-2024) and defines the upper voltage limit imposed on protected circuitry during standardized surge events. The SMAJ18A-M3/61 maintains this clamping performance across its full operating temperature range.
Is the SMAJ18A-M3/61 suitable for automotive applications?
The SMAJ18A-M3/61 is a commercial-grade part, but it shares identical die, package, and electrical characteristics with AEC-Q101 qualified variants (e.g., SMAJ18A-HM3_X). Its -55 °C to +150 °C operating junction temperature range, 400 W surge rating, and halogen-free M3 construction make it technically capable for under-hood and body electronics use-though formal automotive qualification requires the HE3/HM3 suffix. The SMAJ18A-M3/61 is widely deployed in automotive subsystems where full AEC-Q101 certification is not mandated.
How does the SMAJ18A-M3/61 differ from the bidirectional SMAJ18CA-M3/61?
The SMAJ18A-M3/61 is unidirectional, with polarity marked by a cathode band and clamping action only for positive transients relative to ground. The SMAJ18CA-M3/61 is bidirectional, offering symmetric clamping for both positive and negative excursions-essential for AC signals like RS-485 or CAN. Both share identical VWM (18 V), VBR (20.0–22.1 V), VC (29.2 V), and PPPM (400 W), but the SMAJ18A-M3/61 exhibits lower reverse leakage (1.0 μA vs. 2.0 μA for CA types at VWM), making it preferable for DC bias applications.
What is the thermal resistance of the SMAJ18A-M3/61, and how does it affect PCB layout?
The SMAJ18A-M3/61 has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W and junction-to-lead resistance (RθJL) of 30 °C/W, measured on 0.2" × 0.2" copper pads per terminal. To maintain safe junction temperatures under repeated surges, PCB layout must provide adequate copper area-minimum recommended pad dimensions are specified in the Vishay outline drawing (Document 88390, page 5). Reducing RθJA via larger thermal pads directly improves surge endurance and long-term reliability of the SMAJ18A-M3/61.
Does the SMAJ18A-M3/61 require a heatsink for standard operation?
No, the SMAJ18A-M3/61 does not require an external heatsink for normal transient suppression duty cycles (e.g., 0.01 % duty cycle, 10/1000 μs pulses). Its 3.3 W steady-state power dissipation (PD) rating and RθJA = 120 °C/W are sufficient when mounted on the specified 0.2" × 0.2" copper pads. However, for high-frequency or high-duty-cycle surge events, thermal derating per Figure 2 in the datasheet must be applied-and the SMAJ18A-M3/61 should be evaluated in-system with IR thermography to confirm TJ stays below 150 °C.
SMAJ18A-M3/61 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-M3/61 FAQ
1.How can I place an order for SMAJ18A-M3/61 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18A-M3/61 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-M3/61 reliable?
The price and inventory of SMAJ18A-M3/61 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18A-M3/61 is usually 5 days.
3.What payment methods are accepted for SMAJ18A-M3/61?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18A-M3/61 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18A-M3/61?
SMAJ18A-M3/61 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18A-M3/61 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-M3/61?
For technical support, including SMAJ18A-M3/61 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18A-M3/61 requirements.
6.How does Aetrix verify that SMAJ18A-M3/61 is sourced from the original manufacturer or authorized distributors?
All SMAJ18A-M3/61 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-M3/61 meets industry standards.
7.What is the process for return or replacement of SMAJ18A-M3/61?
All SMAJ18A-M3/61 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18A-M3/61, 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-M3/61 part is unused and in its original packaging.
Return procedure for SMAJ18A-M3/61:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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