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Vishay General Semiconductor - Diodes Division SMAJ18CAHM3/H
- Part No.:
- SMAJ18CAHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CAHM3/H.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,343
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Product details
Overview
SMAJ18CAHM3/H 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 SMAJ18CAHM3/H datasheet, SMAJ18CAHM3/H pinout, SMAJ18CAHM3/H application, or SMAJ18CAHM3/H equivalent, this page delivers verified electrical specs, package dimensions, clamping behavior under surge, AEC-Q101 qualification status, and direct alternatives for ESD/lightning transient hardening in 12 V/24 V systems.
Technical Context
This bidirectional TVS diode uses a glass-passivated silicon junction to achieve sub-nanosecond response time and low incremental surge resistance. Its symmetrical I-V characteristics enable identical clamping in both polarities, making it suitable for AC-coupled or floating signal lines where polarity reversal is possible.
The device is rated for 400 W peak pulse power (10/1000 μs waveform) up to 78 V, derating to 300 W above that threshold. Thermal resistance is 120 °C/W (junction-to-ambient) on standard 0.2" × 0.2" copper pads, with MSL Level 1 moisture sensitivity and halogen-free, RoHS-compliant construction per suffix HM3.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before significant leakage; defines safe working margin below clamping threshold |
| VBR (min/max) | 20.0 V / 22.1 V at 1 mA - Confirmed breakdown range ensures reliable turn-on during transients without premature conduction |
| VC @ IPPM | 29.2 V at 13.7 A - Clamped voltage during 400 W surge limits stress on downstream ICs like CAN transceivers or microcontrollers |
| IPPM | 13.7 A - Peak surge current capability with 10/1000 μs waveform; validates protection against ISO 7637-2 Pulse 1/2a/5a |
| PPPM | 400 W - Peak pulse power rating confirms suitability for automotive load-dump and inductive switching events |
| TJ max. | +150 °C - High junction temperature rating supports under-hood and industrial control cabinet deployment |
| Package | SMA (DO-214AC) - Surface-mount outline with 5.28 mm length, 4.50 mm width, and 2.29 mm height; compatible with automated SMT placement |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; meets UL 94 V-0 flammability rating and J-STD-002 solderability requirements. Bidirectional configuration has no polarity marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry (negative polarity event) | Conducts during negative-going surges; forms symmetrical path with cathode for full bidirectional clamping |
| Cathode | Transient current entry (positive polarity event) | Conducts during positive-going surges; enables identical clamping voltage magnitude in both directions |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Identical VBR and VC in both polarities - eliminates need for polarity-aware layout in differential or AC signal paths |
| AEC-Q101 qualified | Validated for automotive applications including engine control modules and body electronics - supports PPAP and long-term reliability requirements |
| Halogen-free & RoHS | HM3 suffix denotes halogen-free molding compound and lead-free terminations - compliant with EU Directive 2011/65/EU and JESD201 Class 2 whisker resistance |
| Low clamping ratio | VC/VWM = 1.62 - tight ratio minimizes overvoltage exposure to protected ICs compared to higher-ratio TVS devices |
| MSL Level 1 | No floor life limitation - can be stored indefinitely at ≤30 °C/60 % RH and mounted without baking prior to reflow |
Applications
| Automotive Sensor Interface | Industrial Digital I/O Protection |
|---|---|
|
Use Scenario: Protecting LIN bus or analog sensor outputs (e.g., pressure, temperature) from load dump and ESD in vehicle ECUs. IC Role / Device Role / Timing Role: Standoff-clamp TVS placed directly at connector entry point to shunt transients before reaching ASIC or MCU input pins. Use Value: Clamps 13.7 A surges to ≤29.2 V, preserving signal integrity and preventing latch-up in 3.3 V/5 V sensor interface ICs. |
Use Scenario: Safeguarding PLC digital input channels exposed to 24 V DC field wiring subject to inductive kickback and lightning-induced surges. IC Role / Device Role / Timing Role: Primary overvoltage clamp on each channel's input node, paired with series current-limiting resistor. Use Value: Withstands repetitive 400 W pulses without degradation, enabling maintenance-free operation in factory automation environments. |
| Consumer Power Adapter Output | Telecom Line Card Surge Protection |
|
Use Scenario: Secondary-side transient suppression on 12 V/19 V DC output rails of wall adapters and laptop chargers. IC Role / Device Role / Timing Role: Fast-response shunt device absorbing residual spikes escaping primary-side filtering and regulation stages. Use Value: Sub-ns response time and 29.2 V clamping prevent overvoltage damage to connected devices during AC line disturbances. |
Use Scenario: Front-end protection for Ethernet PHY or xDSL line drivers handling unshielded twisted-pair connections. IC Role / Device Role / Timing Role: First-line defense against induced surges from nearby lightning strikes or power cross events. Use Value: Symmetrical clamping ensures equal protection for both conductors in balanced signaling, maintaining common-mode rejection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CAHE3/H | Same electrical specs and package; RoHS-compliant but not halogen-free; lacks JESD201 Class 2 whisker resistance | Suitable for commercial-grade industrial equipment where halogen-free requirement is not mandated | Select when cost sensitivity outweighs halogen-free compliance; verify board-level reliability under thermal cycling |
| SMBJ18CAHM3 | Same VWM/VBR/VC, but SMB (DO-214AA) package - 30 % larger footprint and 10 % higher RθJA (130 °C/W) | Better suited for high-power or thermally constrained layouts requiring higher surge margin or easier hand-soldering | Choose when PCB space allows larger package and higher thermal mass improves long-term surge endurance |
Compared with SMAJ18CAHM3/H, SMAJ18CAHE3/H offers identical protection performance without halogen-free assurance, while SMBJ18CAHM3 trades compactness for enhanced thermal robustness and mechanical handling - guiding selection based on compliance mandates and thermal design priorities.
Availability
SMAJ18CAHM3/H is available at Aetrix Electronics and suitable for automotive sensor protection, industrial I/O hardening, and telecom line card surge suppression requiring stable component supply and AEC-Q101 traceability.
Supply support for SMAJ18CAHM3/H 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 designs and manufactures discrete semiconductors including diodes, MOSFETs, and optoelectronics, with emphasis on reliability, efficiency, and application-specific optimization.
The SMAJ series targets board-level transient protection in automotive, industrial, and consumer systems - engineered for fast response, repeatable clamping, and compatibility with automated manufacturing processes.
FAQ
What is the clamping voltage of SMAJ18CAHM3/H at its rated peak pulse current?
The SMAJ18CAHM3/H exhibits a maximum clamping voltage (VC) of 29.2 V when subjected to its peak pulse current (IPPM) of 13.7 A under the standardized 10/1000 μs waveform. This value is measured per ANSI/IEEE C62.35 and ensures predictable overvoltage limiting for protected circuitry. The SMAJ18CAHM3/H maintains this clamping performance across its full operating temperature range.
Is SMAJ18CAHM3/H qualified for automotive applications?
Yes, SMAJ18CAHM3/H is AEC-Q101 qualified, as confirmed by Vishay's ordering code structure (HM3 suffix with "H" reel packaging) and documentation referencing AEC-Q101 compliance in the mechanical data section. This qualification covers stress testing for temperature cycling, humidity, mechanical shock, and surge endurance - validating its use in engine control units, ADAS sensors, and body electronics where SMAJ18CAHM3/H serves as primary transient protection.
How does the bidirectional configuration of SMAJ18CAHM3/H affect its circuit implementation?
The bidirectional configuration of SMAJ18CAHM3/H means it provides symmetrical clamping for both positive and negative transients without polarity marking or orientation dependency. This simplifies PCB layout on AC-coupled lines, differential buses (e.g., RS-485), or floating sensor outputs, eliminating risk of incorrect placement. Unlike unidirectional variants, SMAJ18CAHM3/H conducts equally in either direction once VBR is exceeded - critical for protecting circuits where voltage polarity reversal is possible.
What is the thermal resistance of SMAJ18CAHM3/H, and how does it impact PCB layout?
SMAJ18CAHM3/H has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on minimum recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes standard FR-4 board material and natural convection cooling. To maintain reliability under repetitive surge conditions, designers should ensure adequate copper area and avoid excessive trace length between SMAJ18CAHM3/H and ground planes - as higher RθJA increases junction temperature rise during pulse events.
Does SMAJ18CAHM3/H meet halogen-free and RoHS requirements?
Yes, SMAJ18CAHM3/H carries the HM3 suffix, explicitly denoting halogen-free molding compound and RoHS-compliant construction per EU Directive 2011/65/EU. Vishay confirms compliance in the mechanical data section, including JESD201 Class 2 whisker resistance and UL 94 V-0 flammability rating. This makes SMAJ18CAHM3/H suitable for environmentally regulated markets and applications requiring strict material declarations - such as automotive Tier 1 supply chains and medical-grade power systems.
SMAJ18CAHM3/H 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:
- Telecom
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ18CAHM3/H FAQ
1.How can I place an order for SMAJ18CAHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CAHM3/H 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 SMAJ18CAHM3/H reliable?
The price and inventory of SMAJ18CAHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CAHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ18CAHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CAHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CAHM3/H?
SMAJ18CAHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CAHM3/H 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 SMAJ18CAHM3/H?
For technical support, including SMAJ18CAHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CAHM3/H requirements.
6.How does Aetrix verify that SMAJ18CAHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ18CAHM3/H 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 SMAJ18CAHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ18CAHM3/H?
All SMAJ18CAHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CAHM3/H, 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 SMAJ18CAHM3/H part is unused and in its original packaging.
Return procedure for SMAJ18CAHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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