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Vishay General Semiconductor - Diodes Division SMAJ18CAHM3_A/H
- Part No.:
- SMAJ18CAHM3_A/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CAHM3_A/H.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,365
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Product details
Overview
SMAJ18CAHM3_A/H 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 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), and clamps to ≤29.2 V at 13.7 A peak surge current - deployed in automotive sensor interfaces and industrial I/O protection.
For engineers reviewing the SMAJ18CAHM3_A/H datasheet, SMAJ18CAHM3_A/H pinout, SMAJ18CAHM3_A/H application, or SMAJ18CAHM3_A/H equivalent, this device is selected for robust ESD and lightning surge immunity in bidirectional signal paths where low clamping voltage, fast response (<1 ns), and AEC-Q101 qualification are required.
Technical Context
The SMAJ18CAHM3_A/H operates as a bidirectional avalanche diode, symmetrically clamping both positive and negative transients above its reverse standoff voltage (VWM = 18 V). Its glass-passivated junction enables stable breakdown behavior and low leakage (<1.0 μA at VWM).
It delivers 400 W peak pulse power per 10/1000 μs waveform up to 78 V; above that threshold, rating reduces to 300 W. Thermal resistance is 120 °C/W (junction-to-ambient) on standard 0.2" × 0.2" copper pads, with maximum junction temperature of +150 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; defines safe signal swing range. |
| VBR min/max | 20.0 V / 22.1 V at 1 mA - Confirmed breakdown threshold ensures predictable turn-on during overvoltage events. |
| VC @ IPPM | 29.2 V at 13.7 A - Clamping voltage under full-rated surge; determines maximum stress imposed on protected IC. |
| PPPM | 400 W (10/1000 μs) - Surge energy handling capacity; sufficient for ISO 7637-2 Pulse 1/2a/3a and IEC 61000-4-5 Level 3. |
| ID @ VWM | ≤1.0 μA - Ultra-low reverse leakage preserves signal integrity and battery life in always-on circuits. |
| TJ max | +150 °C - Enables operation in under-hood automotive environments and high-temperature industrial enclosures. |
| Package | SMA (DO-214AC) - Standardized SMT footprint compatible with automated assembly; MSL Level 1, lead-free matte tin terminations. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, bidirectional - no polarity marking; symmetrical two-terminal construction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Transient conduction path | Both terminals function identically; conducts surge current in either direction when voltage exceeds ±VBR. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or differential signal lines without polarity concerns. |
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive-grade reliability including temperature cycling, HAST, and mechanical shock per JESD22. |
| 400 W peak pulse power | Meets stringent transient immunity requirements for CAN, LIN, and sensor supply rails in passenger vehicles. |
| Low clamping ratio (VC/VBR ≈ 1.46) | Minimizes overvoltage exposure to downstream components - critical for 3.3 V/5 V logic and analog front-ends. |
| Halogen-free & RoHS-compliant (HM3) | Complies with automotive environmental standards (e.g., ELV, IMDS) and global manufacturing restrictions. |
Applications
| Automotive Sensor Interface | Industrial PLC Analog Input |
|---|---|
Use Scenario: Protecting Hall-effect and temperature sensor outputs connected to microcontroller ADC inputs in engine control units. IC Role / Device Role / Timing Role: Bidirectional TVS placed between sensor output and MCU pin to clamp ESD and load-dump induced spikes. Use Value: Prevents latch-up or damage to 5 V-tolerant ADC inputs while maintaining <1 μA leakage across -40 °C to +125 °C ambient. |
Use Scenario: Safeguarding 4–20 mA current loop receiver circuitry against field wiring surges in factory automation cabinets. IC Role / Device Role / Timing Role: Primary transient suppressor across input terminals of op-amp-based current-to-voltage converter. Use Value: Limits voltage excursion to ≤29.2 V during 1 kV/500 A surge events, preserving precision resistor tolerance and amplifier offset stability. |
| USB Type-C CC Line Protection | Telecom DSL Line Interface |
Use Scenario: Guarding USB-C configuration channel (CC) pins against contact ESD during hot-plug events. IC Role / Device Role / Timing Role: Low-capacitance TVS placed directly at connector to shunt ±15 kV HBM ESD pulses. Use Value: Achieves sub-nanosecond response with <1.0 μA leakage at 18 V, avoiding signal distortion on 300 kHz CC signaling. |
Use Scenario: Front-end surge suppression on twisted-pair DSL line interface cards exposed to lightning-induced transients. IC Role / Device Role / Timing Role: First-stage protector before transformer coupling and line driver ICs in xDSL modems. Use Value: Handles repeated 10/1000 μs surges up to 400 W without degradation, supporting GR-1089-CORE Level 3 compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18CAHE3_A/H | Same electrical specs; RoHS-compliant but not halogen-free; lacks AEC-Q101 qualification. | Suitable for commercial/industrial use only; not approved for automotive under-hood deployment. | Select when halogen-free content or automotive qualification is not required; lower cost alternative. |
| SMBJ18CAHM3_A/H | Same VWM/VBR/VC ratings but in larger SMB (DO-214AA) package; 600 W PPPM rating. | Higher power handling supports longer surge durations; requires larger PCB area and different pad layout. | Choose when system-level testing demands >400 W margin or legacy board designs use SMB footprint. |
Compared with SMAJ18CAHM3_A/H, the HE3 variant trades halogen-free and automotive qualification for cost savings, while the SMBJ18CAHM3_A/H offers higher surge capacity at the expense of board space - making SMAJ18CAHM3_A/H optimal for space-constrained AEC-Q101-compliant designs.
Availability
SMAJ18CAHM3_A/H is available at Aetrix Electronics and suitable for automotive sensor modules, industrial PLC analog inputs, and telecom line interface designs requiring stable component supply with guaranteed long-term manufacturability.
Supply support for SMAJ18CAHM3_A/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 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 targets high-reliability transient suppression in automotive, industrial, and communications systems - engineered for rapid response, low clamping, and qualification to AEC-Q101 and industry surge standards.
FAQ
What is the clamping voltage of SMAJ18CAHM3_A/H at its rated peak pulse current?
The SMAJ18CAHM3_A/H clamps to a maximum of 29.2 V at its rated peak pulse current of 13.7 A (10/1000 μs waveform). This value is measured under standardized test conditions and defines the upper voltage limit imposed on protected circuitry during surge events - critical for ensuring compatibility with 3.3 V or 5 V logic interfaces downstream of the SMAJ18CAHM3_A/H.
Is SMAJ18CAHM3_A/H qualified for automotive applications?
Yes, SMAJ18CAHM3_A/H is AEC-Q101 qualified, as confirmed by the "HM3" suffix denoting halogen-free, RoHS-compliant, and automotive-grade construction. It undergoes rigorous stress testing including temperature cycling, highly accelerated stress testing (HAST), and mechanical shock per JESD22, making it suitable for under-hood and chassis-mounted electronic control units where SMAJ18CAHM3_A/H must operate reliably from -40 °C to +125 °C.
How does SMAJ18CAHM3_A/H differ from unidirectional SMAJ18A variants?
SMAJ18CAHM3_A/H is bidirectional with symmetrical clamping behavior in both polarities, whereas SMAJ18A is unidirectional and features a cathode band marking. The "CA" suffix indicates bidirectional operation - essential for protecting AC-coupled signals, differential buses, or circuits where voltage polarity reversal may occur. SMAJ18CAHM3_A/H has identical VWM (18 V) and VBR (20.0–22.1 V), but conducts surge current regardless of polarity, unlike SMAJ18A which only clamps positive transients relative to cathode.
What is the thermal resistance of SMAJ18CAHM3_A/H, and how does it affect PCB layout?
SMAJ18CAHM3_A/H 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 minimum recommended pad layout per Vishay's DO-214AC outline; reducing pad size or omitting thermal vias increases junction temperature. For sustained power dissipation or high-ambient environments, designers should verify thermal margins using RθJA and PD = 3.3 W to avoid exceeding the +150 °C TJ max of SMAJ18CAHM3_A/H.
Does SMAJ18CAHM3_A/H meet UL recognition requirements?
Yes, SMAJ18CAHM3_A/H carries Underwriters Laboratory Recognition under UL 497B (QVGQ2) with file number E136766 for both unidirectional and bidirectional devices. This certification confirms compliance with safety standards for transient protectors used in telecommunications and data line applications - validating its suitability for use in UL-certified end equipment where SMAJ18CAHM3_A/H serves as primary or secondary surge suppression.
SMAJ18CAHM3_A/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:
- 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:
- 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_A/H FAQ
1.How can I place an order for SMAJ18CAHM3_A/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CAHM3_A/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_A/H reliable?
The price and inventory of SMAJ18CAHM3_A/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_A/H is usually 5 days.
3.What payment methods are accepted for SMAJ18CAHM3_A/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CAHM3_A/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CAHM3_A/H?
SMAJ18CAHM3_A/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CAHM3_A/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_A/H?
For technical support, including SMAJ18CAHM3_A/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CAHM3_A/H requirements.
6.How does Aetrix verify that SMAJ18CAHM3_A/H is sourced from the original manufacturer or authorized distributors?
All SMAJ18CAHM3_A/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_A/H meets industry standards.
7.What is the process for return or replacement of SMAJ18CAHM3_A/H?
All SMAJ18CAHM3_A/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CAHM3_A/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_A/H part is unused and in its original packaging.
Return procedure for SMAJ18CAHM3_A/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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