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Vishay General Semiconductor - Diodes Division SMAJ18AHE3/5A
- Part No.:
- SMAJ18AHE3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18AHE3/5A.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,204
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Product details
Overview
SMAJ18AHE3/5A from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of sensitive electronics. 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), commonly deployed on power rails and I/O lines of automotive ECUs and industrial sensor interfaces.
For engineers reviewing the SMAJ18AHE3/5A datasheet, SMAJ18AHE3/5A pinout, SMAJ18AHE3/5A application, or SMAJ18AHE3/5A equivalent, key selection criteria include its AEC-Q101 qualification, low clamping ratio (VC/VBR ≈ 1.42), 1.0 μA max reverse leakage at VWM, and compatibility with automated SMT assembly on standard PCB pad layouts per JEDEC DO-214AC footprint.
Technical Context
This unidirectional TVS diode operates as a voltage-clamped shunt protector: under normal conditions it presents high impedance (>1 MΩ), but triggers into low-impedance conduction when transient voltage exceeds VBR, diverting surge current away from downstream ICs. Its glass-passivated junction ensures stable breakdown characteristics and long-term reliability under repetitive transients.
The device is rated for 40 A non-repetitive forward surge current (IFSM, 8.3 ms half-sine), supports operating junction temperatures from –55 °C to +150 °C, and meets MSL Level 1 per J-STD-020 with peak reflow temperature up to 260 °C - confirming suitability for lead-free reflow processes without preconditioning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - maximum continuous reverse working voltage before significant leakage; defines safe operating margin below clamping threshold |
| VBR (min/max) | 20.0 V / 22.1 V at 1 mA - precise breakdown onset range ensuring predictable turn-on during transients |
| VC @ IPPM | 29.2 V at 13.7 A - clamping voltage under 10/1000 μs surge; limits stress on protected circuitry |
| PPPM | 400 W - peak pulse power handling capability; enables suppression of high-energy ESD and load-dump events |
| ID @ VWM | 1.0 μA - ultra-low reverse leakage at rated stand-off voltage, minimizing standby power loss |
| TJ max. | +150 °C - maximum junction temperature rating supporting operation in under-hood automotive and industrial environments |
| AEC-Q101 | Qualified - validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing per AEC specification |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, low-profile plastic case with matte tin-plated leads; compliant with UL 94 V-0 flammability rating and J-STD-002 solderability requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Protected line connection point | Connected to the line requiring overvoltage protection (e.g., 12 V rail); anode ties to ground or lower potential reference |
| Anode | Reference/return path | Typically connected to system ground; completes shunt path for transient current during clamping |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control, body electronics, and ADAS sensors |
| 400 W peak pulse power (10/1000 μs) | Robustly handles ISO 7637-2 Load Dump Pulse 5a (up to 120 V, 100 ms) and IEC 61000-4-5 surges |
| Low clamping ratio (VC/VBR ≈ 1.42) | Minimizes voltage overshoot during clamping, reducing risk of latch-up or damage to downstream MOSFETs or MCUs |
| MSL Level 1, 260 °C peak reflow | Enables direct placement into lead-free SMT lines without moisture sensitivity concerns or baking requirements |
| Glass passivated junction | Ensures stable VBR over time and temperature, critical for long-life deployments in harsh environments |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
|
Use Scenario: Protecting 12 V supply lines in engine control units against load dump transients up to 120 V. IC Role / Device Role / Timing Role: Unidirectional shunt TVS diode placed between battery rail and local regulator input. Use Value: Clamps transients to ≤29.2 V within nanoseconds, preventing regulator latch-up and MCU brownout. |
Use Scenario: Safeguarding analog output lines (e.g., 4–20 mA current loop) of pressure sensors in factory automation. IC Role / Device Role / Timing Role: Bidirectional-capable protection element (though SMAJ18AHE3/5A is unidirectional, used with series resistor for bidirectional effect) on signal path to PLC input. Use Value: Limits induced surge voltages to <30 V, preserving ADC front-end integrity and avoiding calibration drift. |
| Consumer Power Adapter Input Stage | Telecom DC Power Feeding Line |
|
Use Scenario: Secondary-side overvoltage clamp in USB-C PD adapter auxiliary power circuits. IC Role / Device Role / Timing Role: Standby-mode protector across 5–20 V output rails during hot-plug and fault conditions. Use Value: Sub-1 μA leakage at 18 V maintains low no-load power consumption while enabling fast (<1 ns) response to fast-rising spikes. |
Use Scenario: Surge protection on -48 V DC feeding lines for remote radio units in 5G base stations. IC Role / Device Role / Timing Role: Unidirectional TVS referenced to chassis ground on power return path. Use Value: Withstands repeated 10/1000 μs surges up to 400 W, meeting GR-1089-CORE Level 3 telecom immunity requirements. |
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 | No AEC-Q101 qualification; commercial-grade only; identical electrical specs and package | Not approved for automotive production; suitable for consumer or industrial prototypes | Select when AEC-Q101 is not required and cost optimization is prioritized |
| SMAJ18AHM3/5A | Halogen-free, RoHS-compliant variant; same AEC-Q101 qualification and electrical performance | Required where halogen-free compliance is mandated by OEM or regional environmental regulations | Choose for automotive Tier 1 supply chains enforcing IPC-1752A material declarations |
Compared with SMAJ18AHE3/5A, the E3/5A variant lacks automotive qualification but offers identical clamping and thermal behavior for non-automotive use, while HM3/5A adds halogen-free construction without sacrificing AEC-Q101 compliance - enabling design reuse across commercial and regulated automotive programs.
Availability
SMAJ18AHE3/5A is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor modules, and telecom power interface designs requiring stable component supply and full AEC-Q101 traceability.
Supply support for SMAJ18AHE3/5A 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 validation.
The SMAJ series is engineered for high-energy transient suppression in automotive, industrial, and telecom systems - delivering consistent clamping performance and AEC-Q101 assurance in compact surface-mount packages.
FAQ
What is the clamping voltage of SMAJ18AHE3/5A at its rated peak pulse current?
The SMAJ18AHE3/5A 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 test condition defined in the Vishay datasheet (Document Number: 88390), and directly determines the upper voltage limit imposed on protected circuitry during surge events. The SMAJ18AHE3/5A maintains this clamping performance across its qualified operating temperature range.
Is SMAJ18AHE3/5A suitable for automotive applications?
Yes, SMAJ18AHE3/5A is AEC-Q101 qualified, meaning it has passed rigorous stress tests including temperature cycling, high-temperature reverse bias, and ESD verification required for automotive electronics. Its operating junction temperature range (–55 °C to +150 °C), MSL Level 1 reflow rating, and stable VBR/VC characteristics make it appropriate for under-hood and cabin applications such as body control modules and ADAS sensor power rails. The SMAJ18AHE3/5A part number explicitly denotes this qualification via the "HE3" suffix.
What does the "HE3" suffix indicate in SMAJ18AHE3/5A?
The "HE3" suffix in SMAJ18AHE3/5A identifies the part as RoHS-compliant and AEC-Q101 qualified, distinguishing it from commercial-grade variants like SMAJ18A-E3/5A (no AEC-Q101) or halogen-free versions like SMAJ18AHM3/5A. Per Vishay's ordering nomenclature, "HE3" confirms both environmental compliance and automotive reliability validation. This designation is critical for traceability in automotive BOMs and ensures the SMAJ18AHE3/5A meets OEM requirements for qualification documentation and lot-level reporting.
How does SMAJ18AHE3/5A differ from bidirectional TVS diodes like SMAJ18CA?
SMAJ18AHE3/5A is unidirectional and features a cathode band for polarity-sensitive placement, whereas SMAJ18CA is bidirectional with symmetric breakdown in both directions and no polarity marking. The unidirectional SMAJ18AHE3/5A provides lower forward voltage drop (VF = 3.5 V at 25 A) and is preferred for DC power rail protection where polarity is fixed. In contrast, SMAJ18CA suits AC-coupled or floating signal lines. Both share the same VWM (18 V) and VC (29.2 V), but SMAJ18AHE3/5A cannot replace SMAJ18CA in true bidirectional configurations without circuit redesign.
What is the thermal resistance of SMAJ18AHE3/5A, and how does it affect layout design?
The SMAJ18AHE3/5A 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 JEDEC DO-214AC guidelines. These values mean that sustained power dissipation above ~300 mW can cause significant junction temperature rise - so layout must include adequate copper area and thermal vias if operating near its 3.3 W steady-state power limit. For transient-only use (e.g., ESD), thermal design is less critical, but the SMAJ18AHE3/5A's RθJL supports rapid heat transfer to PCB traces during short pulses.
SMAJ18AHE3/5A 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:
- 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ18AHE3/5A FAQ
1.How can I place an order for SMAJ18AHE3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18AHE3/5A 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 SMAJ18AHE3/5A reliable?
The price and inventory of SMAJ18AHE3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18AHE3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ18AHE3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18AHE3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18AHE3/5A?
SMAJ18AHE3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18AHE3/5A 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 SMAJ18AHE3/5A?
For technical support, including SMAJ18AHE3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18AHE3/5A requirements.
6.How does Aetrix verify that SMAJ18AHE3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ18AHE3/5A 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 SMAJ18AHE3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ18AHE3/5A?
All SMAJ18AHE3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18AHE3/5A, 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 SMAJ18AHE3/5A part is unused and in its original packaging.
Return procedure for SMAJ18AHE3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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