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Vishay General Semiconductor - Diodes Division SMAJ18CAHE3/5A
- Part No.:
- SMAJ18CAHE3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CAHE3/5A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,021
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Product details
Overview
SMAJ18CAHE3/5A from Vishay General Semiconductor is a bidirectional surface-mount Transient Voltage Suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on signal or power 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), used to protect MOSFETs, ICs, and sensor signal lines in automotive and industrial systems.
For engineers reviewing the SMAJ18CAHE3/5A datasheet, SMAJ18CAHE3/5A pinout, SMAJ18CAHE3/5A application, or SMAJ18CAHE3/5A equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification, 150 °C max junction temperature, low incremental surge resistance, and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.
Technical Context
This TVS diode operates symmetrically in both directions due to its bidirectional construction, enabling protection of AC-coupled or differential signal paths without polarity concerns. Its glass-passivated junction ensures stable breakdown behavior and low leakage (<1.0 μA at VWM), while the low RθJA of 120 °C/W supports thermal reliability under repetitive surge conditions.
The device delivers 400 W peak pulse power up to 78 V and derates to 300 W above that threshold, with clamping performance validated per ANSI/IEEE C62.35. It meets MSL Level 1 per J-STD-020 and is qualified to AEC-Q101, confirming suitability for automotive electronics subjected to harsh thermal and mechanical stress profiles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before clamping initiates; defines safe signal line operating margin. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed breakdown range ensuring predictable turn-on during overvoltage events. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage seen by protected circuit during 10/1000 μs transient; limits stress on downstream components. |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - Peak surge energy absorption capacity under standardized waveform; determines survivability against lightning or ESD-like pulses. |
| ID @ VWM | <1.0 μA - Reverse leakage current at stand-off voltage; ensures minimal signal loading and power loss in standby. |
| TJ max | +150 °C - Maximum junction temperature rating; enables operation in under-hood automotive or high-ambient industrial environments. |
| Package | SMA (DO-214AC) - Standardized surface-mount outline with 5.0 mm × 5.0 mm thermal pad footprint; compatible with JEDEC-compliant reflow profiles. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated, MSL Level 1, 260 °C peak reflow temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal in forward bias; common node in bidirectional configuration | No marking; symmetrical conduction path - either terminal may serve as input or return depending on transient polarity. |
| Cathode | Current exit terminal in forward bias; common node in bidirectional configuration | No band or marking on bidirectional types; terminals are electrically interchangeable for transient suppression across AC or differential lines. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, humidity, and mechanical shock - required for engine control, ADAS, and infotainment modules. |
| 400 W peak pulse power (10/1000 μs) | Withstands high-energy transients induced by inductive load switching (e.g., fuel injectors, solenoids) without degradation. |
| Low clamping voltage (VC = 29.2 V) | Minimizes voltage overshoot on protected 18 V rails, preserving margin for 3.3 V/5 V logic interfaces and analog front-ends. |
| Glass passivated junction | Ensures stable VBR tolerance and low leakage over lifetime and temperature - critical for long-term field reliability in unattended systems. |
| MSL Level 1, 260 °C peak reflow | Enables single-pass lead-free reflow assembly without moisture-induced popcorn failure or bond wire damage. |
Applications
| Automotive Power Line Protection | Industrial Sensor Signal Conditioning |
|---|---|
|
Use Scenario: Protecting 12 V/24 V power distribution networks in vehicle ECUs from load dump and alternator ripple. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed between power rail and ground, responding within <1 ps to suppress >100 V spikes. Use Value: Prevents latch-up or permanent damage to microcontrollers and CAN transceivers during ISO 7637-2 Pulse 5a events. |
Use Scenario: Shielding analog output lines (e.g., 4–20 mA current loops) of pressure or temperature sensors in factory automation. IC Role / Device Role / Timing Role: Low-leakage transient shunt mounted directly at connector interface to divert ESD and cable discharge currents. Use Value: Maintains signal integrity below 1 μA leakage at 18 V, avoiding offset errors in precision measurement circuits. |
| Consumer USB Interface Protection | Telecom DSL Line Surge Suppression |
|
Use Scenario: Safeguarding USB 2.0 data lines (D+/D−) in portable chargers and docking stations against human-body-model ESD. IC Role / Device Role / Timing Role: Symmetric bidirectional clamp with matched VBR on both lines, minimizing differential skew during fast transients. Use Value: Achieves <1 ns response time and sub-30 V clamping to prevent PHY layer damage without affecting 480 Mbps signaling integrity. |
Use Scenario: Front-end protection of ADSL/VDSL line drivers exposed to lightning-induced surges on outdoor copper pairs. IC Role / Device Role / Timing Role: High-power TVS placed before transformer coupling to absorb multi-kV transients before reaching integrated line interface ICs. Use Value: Handles 400 W pulses with 29.2 V clamping, reducing stress on downstream 100 V-rated amplifiers and improving system-level surge immunity to IEC 61000-4-5 Level 4. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CA-M3/5A | Halogen-free, RoHS-compliant variant; identical electrical specs and AEC-Q101 qualification. | No functional difference; selected when halogen-free material compliance is mandated by OEM or regional environmental policy. | Choose SMAJ18CA-M3/5A if halogen-free bill-of-materials is required; otherwise SMAJ18CAHE3/5A offers same performance with standard RoHS compliance. |
| SMAJ18AHE3/5A | Unidirectional version - cathode-banded, 18 V VWM, same VC and PPPM but asymmetric conduction. | Requires correct polarity orientation; unsuitable for AC or floating differential lines where bidirectional clamping is essential. | Select SMAJ18AHE3/5A only for DC power rails with known polarity; SMAJ18CAHE3/5A is mandatory for bidirectional signal paths like RS-485 or USB. |
Compared with SMAJ18CA-M3/5A, SMAJ18CAHE3/5A provides identical surge protection performance with standard RoHS compliance; compared with SMAJ18AHE3/5A, it enables polarity-agnostic placement and protects AC-coupled interfaces - making it the only suitable choice for differential or floating signal lines.
Availability
SMAJ18CAHE3/5A is available at Aetrix Electronics and suitable for automotive ECU design, industrial sensor interface development, and telecom line card prototyping requiring stable component supply and AEC-Q101 traceability.
Supply support for SMAJ18CAHE3/5A 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, efficiency, and application-specific optimization.
The SMAJ series is engineered for robust transient suppression in demanding environments - targeting automotive, industrial, and communications systems where failure due to voltage surges must be eliminated.
FAQ
What is the clamping voltage of SMAJ18CAHE3/5A at its rated peak pulse current?
The SMAJ18CAHE3/5A has a maximum clamping voltage (VC) of 29.2 V at 13.7 A peak pulse current (IPPM), measured under the standardized 10/1000 μs waveform. This value ensures protected circuits experience limited overvoltage stress during surge events, and is confirmed in the Vishay datasheet Document Number 88390, Table on page 2. The SMAJ18CAHE3/5A maintains this clamping performance across its full operating temperature range.
Is SMAJ18CAHE3/5A suitable for automotive applications?
Yes, SMAJ18CAHE3/5A is AEC-Q101 qualified, as explicitly stated in the Vishay datasheet revision 09-Jan-2024. It undergoes rigorous testing for temperature cycling, humidity, mechanical shock, and surge endurance - meeting requirements for engine control units, body electronics, and ADAS modules. The SMAJ18CAHE3/5A also complies with MSL Level 1 and supports lead-free reflow, fulfilling automotive manufacturing standards.
How does SMAJ18CAHE3/5A differ from unidirectional SMAJ18AHE3/5A?
SMAJ18CAHE3/5A is bidirectional with no polarity marking and symmetrical clamping in both directions, while SMAJ18AHE3/5A is unidirectional with a cathode band and conducts only in reverse bias. The SMAJ18CAHE3/5A is required for AC-coupled, differential, or floating signal lines (e.g., RS-485, USB); SMAJ18AHE3/5A is limited to DC rails with fixed polarity. Their VWM, VC, and PPPM ratings are otherwise identical.
What is the thermal resistance of SMAJ18CAHE3/5A, and how does it affect layout?
The SMAJ18CAHE3/5A 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. To maintain safe operation under repetitive surges, PCB layout must replicate this pad area - undersized traces or insufficient copper will raise junction temperature beyond the +150 °C limit. The SMAJ18CAHE3/5A's RθJL of 30 °C/W further emphasizes the need for solid thermal connection to internal ground planes.
Does SMAJ18CAHE3/5A have a specified junction capacitance?
No, the Vishay datasheet Document Number 88390 does not specify junction capacitance (CJ) for SMAJ18CAHE3/5A. While Figure 4 shows typical CJ curves for the SMAJ family, values are given only for VWM = 5.0 V to 48 V variants - and SMAJ18CAHE3/5A (VWM = 18 V) falls outside the plotted range. For high-speed signal line protection where capacitance matters, designers should consult Vishay's application notes or characterize CJ empirically; the SMAJ18CAHE3/5A is primarily intended for power and lower-frequency signal protection.
SMAJ18CAHE3/5A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Package/Case:
- DO-214AC, SMA
- Series:
- TransZorb®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ18CAHE3/5A FAQ
1.How can I place an order for SMAJ18CAHE3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CAHE3/5A 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 SMAJ18CAHE3/5A reliable?
The price and inventory of SMAJ18CAHE3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CAHE3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ18CAHE3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CAHE3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CAHE3/5A?
SMAJ18CAHE3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CAHE3/5A 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 SMAJ18CAHE3/5A?
For technical support, including SMAJ18CAHE3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CAHE3/5A requirements.
6.How does Aetrix verify that SMAJ18CAHE3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ18CAHE3/5A 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 SMAJ18CAHE3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ18CAHE3/5A?
All SMAJ18CAHE3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CAHE3/5A, 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 SMAJ18CAHE3/5A part is unused and in its original packaging.
Return procedure for SMAJ18CAHE3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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