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Vishay General Semiconductor - Diodes Division SMAJ18CA-E3/61
- Part No.:
- SMAJ18CA-E3/61
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CA-E3/61.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,318
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Product details
Overview
SMAJ18CA-E3/61 from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode designed for robust overvoltage protection on signal and power lines. It features a 18 V standoff voltage (VWM), 20.0–22.1 V breakdown voltage (VBR) at 1 mA, 400 W peak pulse power (10/1000 μs), clamping voltage of 29.2 V at 13.7 A, and operates across –55 °C to +150 °C junction temperature range - deployed in automotive sensor interfaces and industrial I/O protection.
For engineers reviewing the SMAJ18CA-E3/61 datasheet, SMAJ18CA-E3/61 pinout, SMAJ18CA-E3/61 application, or SMAJ18CA-E3/61 equivalent, key selection criteria include bidirectional clamping capability, UL 497B recognition, AEC-Q101 qualification eligibility (via HE3 suffix variants), low thermal resistance (RθJA = 120 °C/W), and compatibility with automated SMT placement on DO-214AC footprints.
Technical Context
This device functions as a silicon avalanche diode optimized for fast-response transient suppression. Its bidirectional architecture enables symmetrical clamping in both polarities without external polarity management, and its glass-passivated junction ensures stable leakage (<1.0 μA at VWM) and repeatable breakdown behavior under repetitive surge conditions.
The SMAJ18CA-E3/61 delivers 400 W peak pulse power per the 10/1000 μs waveform standard (derated to 300 W above 78 V), with a typical clamping ratio (VC/VBR) of ~1.45 and low incremental surge resistance - critical for limiting let-through energy during ESD or load-switching transients in 12 V and 24 V systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before significant conduction begins; defines safe operating margin below clamping threshold. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed breakdown range ensuring reliable turn-on during transients while avoiding false triggering. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage seen by protected circuit during full-rated 400 W surge; limits downstream stress. |
| PPPM | 400 W (10/1000 μs) - Peak transient energy absorption capacity; sufficient for ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 Level 3 events. |
| IFSM | 40 A (8.3 ms half-sine) - Surge current rating for unidirectional variants; confirms ruggedness against inrush or fault currents. |
| TJ max | +150 °C - Maximum junction temperature enabling use in under-hood automotive and high-ambient industrial environments. |
| RθJA | 120 °C/W - Thermal resistance from junction to ambient on standard 0.2" × 0.2" copper pads; informs derating requirements for sustained power dissipation. |
Pinout & Package
Package: SMA (DO-214AC) - surface-mount, low-profile plastic case with matte tin-plated leads, compliant with J-STD-002 solderability and JESD 22-B102 whisker testing. Molding compound meets UL 94 V-0. No polarity marking for bidirectional types.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry (negative polarity) | One terminal of symmetrical avalanche junction; conducts during negative transients relative to cathode reference. |
| Cathode | Transient current entry (positive polarity) | Other terminal of symmetrical junction; conducts during positive transients - functionally identical to anode in bidirectional operation. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating lines (e.g., RS-485, CAN, sensor bridges) without polarity constraints. |
| 400 W peak pulse power | Meets stringent automotive and industrial surge immunity standards (ISO 7637-2, IEC 61000-4-5) with margin for system-level compliance. |
| UL 497B recognized | Validated for telecom and data line protection applications requiring Underwriters Laboratories certification (File E136766). |
| AEC-Q101 qualified option | HE3/HM3 suffix variants support automotive-grade reliability; base E3 version is commercial-grade but shares identical die and package. |
| MSL Level 1 (260 °C) | Compatible with standard lead-free reflow profiles without moisture sensitivity concerns - eliminates bake requirements pre-assembly. |
Applications
| Automotive Sensor Protection | Industrial I/O Interface |
|---|---|
|
Use Scenario: Protecting analog outputs (e.g., 0–5 V throttle position sensor signals) from load-dump and inductive switching transients in 12 V vehicle subsystems. IC Role / Device Role / Timing Role: Standoff-clamp TVS placed directly at connector entry point to shunt surges before reaching precision ADC front-end. Use Value: Limits transient voltage to ≤29.2 V, preserving signal integrity and preventing damage to 5 V-tolerant microcontroller inputs. |
Use Scenario: Safeguarding 24 V PLC digital input channels exposed to relay coil flyback and field wiring faults. IC Role / Device Role / Timing Role: Bidirectional clamp across input terminals to absorb both positive and negative polarity transients without polarity-aware layout. Use Value: Withstands 400 W surges while maintaining <1.0 μA leakage at 18 V, ensuring minimal impact on input threshold detection. |
| Telecom Line Protection | Consumer Power Adapter Input |
|
Use Scenario: Secondary-side protection on Ethernet PHY power rails (e.g., 3.3 V bias supply) against ESD and lightning-induced surges. IC Role / Device Role / Timing Role: Fast-response TVS (sub-nanosecond turn-on) placed adjacent to PHY IC to minimize trace inductance and let-through voltage. Use Value: Clamps 13.7 A surge to 29.2 V within nanoseconds, preventing latch-up or gate oxide damage in sensitive transceivers. |
Use Scenario: Input-stage surge suppression on AC-DC adapter primary-side rectifier output (e.g., 300 V DC bus) against mains transients. IC Role / Device Role / Timing Role: Not applicable - SMAJ18CA-E3/61 rated only to 188 V VWM; this application requires higher-voltage variant (e.g., SMAJ188CA). Use Value: Not applicable - SMAJ18CA-E3/61 is unsuitable for >188 V working voltages; selecting it here would violate maximum standoff rating. |
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 | Unidirectional variant with identical VWM, VBR, and VC; includes cathode band marking. | Requires explicit polarity assignment in PCB layout; suitable where circuit ground reference is fixed and transients are known-polarity. | Select SMAJ18A-E3/61 only when system topology guarantees unidirectional surge direction and space allows polarity-aware placement. |
| SMBJ18CA-E3/52 | Same electrical specs but in SMB (DO-214AA) package - 2.6 mm × 4.6 mm vs. SMA's 2.3 mm × 4.3 mm; 600 W PPPM. | Higher power handling and larger pad area; better thermal performance but occupies more board area. | Choose SMBJ18CA-E3/52 when surge duty cycle or ambient temperature demands higher power derating margin than SMAJ18CA-E3/61 provides. |
Compared with SMAJ18A-E3/61, the SMAJ18CA-E3/61 eliminates polarity dependency for floating or AC-coupled lines; versus SMBJ18CA-E3/52, it trades 200 W peak power headroom for 25 % smaller footprint and tighter layout integration in space-constrained modules.
Availability
SMAJ18CA-E3/61 is available at Aetrix Electronics and suitable for automotive sensor interfaces, industrial PLC I/O modules, telecom PHY protection, and consumer electronics ESD hardening requiring stable component supply and RoHS-compliant sourcing.
Supply support for SMAJ18CA-E3/61 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, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific performance.
The SMAJ series is engineered for high-reliability transient suppression in harsh environments - targeting automotive, industrial control, and communications infrastructure where robustness against electrical overstress is mission-critical.
FAQ
What does the "CA" suffix mean in SMAJ18CA-E3/61?
The "CA" suffix denotes a bidirectional configuration: SMAJ18CA-E3/61 provides symmetrical clamping for both positive and negative voltage transients without polarity dependence. Unlike unidirectional "A" variants (e.g., SMAJ18A-E3/61), it has no cathode marking and functions identically in either orientation - essential for protecting AC-coupled or floating signal lines such as RS-485 or bridge sensor outputs. This makes SMAJ18CA-E3/61 ideal for applications where transient polarity cannot be guaranteed.
Is SMAJ18CA-E3/61 AEC-Q101 qualified?
SMAJ18CA-E3/61 itself is the commercial-grade RoHS-compliant variant (E3 suffix). However, Vishay offers AEC-Q101 qualified versions under the HE3 and HM3 suffixes (e.g., SMAJ18CAHE3_A). These share identical electrical characteristics and DO-214AC packaging but undergo additional automotive reliability testing including temperature cycling, humidity bias, and accelerated life testing. For automotive designs requiring formal qualification, specify the HE3 variant - SMAJ18CA-E3/61 remains suitable for non-automotive industrial and consumer applications.
What is the maximum clamping voltage of SMAJ18CA-E3/61 under surge conditions?
The maximum clamping voltage (VC) of SMAJ18CA-E3/61 is 29.2 V at a peak pulse current (IPPM) of 13.7 A, measured with a 10/1000 μs waveform. This value represents the upper limit of voltage imposed on the protected circuit during a full-rated 400 W transient event. Designers must ensure downstream components (e.g., microcontroller I/O pins, op-amp inputs) have absolute maximum ratings exceeding 29.2 V to avoid damage - confirming that SMAJ18CA-E3/61 provides effective let-through voltage control for 18 V nominal systems.
Can SMAJ18CA-E3/61 be used in place of SMAJ18A-E3/61?
SMAJ18CA-E3/61 can replace SMAJ18A-E3/61 only if the application requires bidirectional protection and the PCB layout does not rely on polarity marking for assembly or diagnostics. Electrically, both share identical VWM (18 V), VBR (20.0–22.1 V), and VC (29.2 V), but SMAJ18A-E3/61 includes a cathode band and conducts only in one direction. Substituting SMAJ18CA-E3/61 in a unidirectionally biased circuit introduces no functional risk - however, it forfeits polarity-based fault detection and may complicate failure analysis. Always verify system-level surge directionality before interchange.
What is the thermal resistance and how does it affect layout for SMAJ18CA-E3/61?
SMAJ18CA-E3/61 has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes minimal copper area; increasing pad size or adding thermal vias reduces RθJA and improves power handling during repetitive surges. For designs expecting frequent transients, allocate ≥5 mm² copper per pad and use ≥2 thermal vias (0.3 mm diameter) under each pad to maintain junction temperature below 150 °C - ensuring long-term reliability of SMAJ18CA-E3/61 in thermally demanding environments.
SMAJ18CA-E3/61 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:
- -
- Bidirectional Channels:
- 1
- 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)
SMAJ18CA-E3/61 FAQ
1.How can I place an order for SMAJ18CA-E3/61 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CA-E3/61 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 SMAJ18CA-E3/61 reliable?
The price and inventory of SMAJ18CA-E3/61 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CA-E3/61 is usually 5 days.
3.What payment methods are accepted for SMAJ18CA-E3/61?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CA-E3/61 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CA-E3/61?
SMAJ18CA-E3/61 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CA-E3/61 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 SMAJ18CA-E3/61?
For technical support, including SMAJ18CA-E3/61 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CA-E3/61 requirements.
6.How does Aetrix verify that SMAJ18CA-E3/61 is sourced from the original manufacturer or authorized distributors?
All SMAJ18CA-E3/61 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 SMAJ18CA-E3/61 meets industry standards.
7.What is the process for return or replacement of SMAJ18CA-E3/61?
All SMAJ18CA-E3/61 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CA-E3/61, 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 SMAJ18CA-E3/61 part is unused and in its original packaging.
Return procedure for SMAJ18CA-E3/61:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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