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Vishay General Semiconductor - Diodes Division SMAJ18CAHM3/I
- Part No.:
- SMAJ18CAHM3/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CAHM3/I.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:3,134
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Product details
Overview
SMAJ18CAHM3/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode designed for robust overvoltage protection of sensitive electronics. 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 transients to ≤29.2 V at 13.7 A peak surge current - deployed on signal lines and power rails in automotive sensor modules and industrial I/O interfaces.
For engineers reviewing the SMAJ18CAHM3/I datasheet, SMAJ18CAHM3/I pinout, SMAJ18CAHM3/I application, or SMAJ18CAHM3/I equivalent, this page delivers verified electrical specs, package dimensions, clamping behavior under surge conditions, thermal derating curves, and AEC-Q101-qualified alternatives for automotive-grade ESD and load-dump protection design.
Technical Context
The SMAJ18CAHM3/I operates as a bidirectional avalanche diode with symmetrical clamping in both polarities, enabling protection of AC-coupled or floating signal paths without polarity concerns. Its glass-passivated junction ensures stable VBR tolerance (±5%) and low leakage (<1.0 μA at 18 V), while the DO-214AC (SMA) package supports automated SMT placement and meets MSL Level 1 reflow standards up to 260 °C.
It delivers 400 W peak pulse power at TA = 25 °C with 10/1000 μs waveform, derating linearly above 25 °C per Fig. 2 (RθJA = 120 °C/W). The device sustains repetitive surges at 0.01% duty cycle and exhibits fast response time (<1.0 ps), making it suitable for protecting MOSFET gates, microcontroller I/O pins, and CAN bus transceivers against ISO 7637-2 Pulse 1/2a/5a events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - maximum continuous reverse operating voltage before clamping begins; defines safe working range for 18 V nominal systems. |
| VBR (min/max) | 20.0 V / 22.1 V at IT = 1 mA - guaranteed breakdown window ensuring predictable turn-on during transients. |
| VC @ IPPM | 29.2 V at 13.7 A - clamping voltage under full 400 W surge; determines maximum stress imposed on protected IC. |
| PPPM | 400 W (10/1000 μs) - peak transient energy absorption capability; sufficient for automotive load dump and inductive switching. |
| ID @ VWM | <1.0 μA - ultra-low leakage preserves signal integrity and battery life in always-on circuits. |
| TJ max. | +150 °C - enables operation in under-hood automotive environments and high-ambient industrial enclosures. |
| Package | SMA (DO-214AC) - surface-mount outline with 5.28 mm × 4.50 mm footprint and 2.29 mm height; compatible with standard 0.2" × 0.2" copper pads. |
Pinout & Package
Package: SMA (DO-214AC), bidirectional configuration - no polarity marking; symmetric terminals function as interchangeable anode/cathode pair.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Terminal 1) | Transient current entry (negative polarity) | Accepts reverse surge current during negative-going transients; connects to protected line or ground reference. |
| Cathode (Terminal 2) | Transient current entry (positive polarity) | Accepts forward surge current during positive-going transients; connects to same protected line or ground reference. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC signals, differential buses (e.g., RS-485, CAN), and floating sensors without external polarity management. |
| AEC-Q101 qualified (HM3 suffix) | Validated for automotive applications including engine control units, ADAS camera modules, and body electronics per stress test requirements. |
| Halogen-free & RoHS-compliant | Meets environmental compliance mandates for global OEM supply chains and industrial equipment export regulations. |
| MSL Level 1 rating | Supports lead-free reflow up to 260 °C peak without moisture-induced damage - eliminates baking requirement prior to assembly. |
| Low incremental surge resistance | Minimizes voltage overshoot during fast-rising transients (e.g., ESD >15 kV), improving immunity margin for sub-20 V logic interfaces. |
Applications
| Automotive Sensor Protection | Industrial PLC I/O Protection |
|---|---|
|
Use Scenario: Protecting analog output lines of pressure/temperature sensors in engine bay modules exposed to ISO 7637-2 load dump pulses. IC Role / Device Role / Timing Role: Bidirectional TVS placed between sensor output and microcontroller ADC input to clamp transients before they reach precision front-end circuitry. Use Value: Limits voltage excursion to ≤29.2 V during 400 W surges, preventing ADC saturation and latch-up in 3.3 V/5 V MCU domains. |
Use Scenario: Shielding digital input channels of programmable logic controllers from inductive kickback when controlling solenoids and relays. IC Role / Device Role / Timing Role: Parallel-connected TVS across 24 V DC input terminals to shunt surge energy away from optocoupler input stages. Use Value: Withstands 13.7 A peak current at 29.2 V clamping, preserving optocoupler CTR and enabling reliable state detection under repeated switching stress. |
| Consumer USB Port ESD Guard | Telecom Line Interface Protection |
|
Use Scenario: Secondary-level ESD protection on USB 2.0 D+/D− lines downstream of integrated port protectors in set-top boxes and smart displays. IC Role / Device Role / Timing Role: Low-capacitance bidirectional clamp absorbing ±15 kV contact discharge per IEC 61000-4-2 without distorting 480 Mbps data eye. Use Value: Sub-1.0 μA leakage at 18 V prevents DC bias shift on high-impedance USB termination resistors, maintaining signal integrity. |
Use Scenario: Overvoltage protection on Ethernet PHY side of PoE-powered access points subjected to lightning-induced surges on twisted-pair cabling. IC Role / Device Role / Timing Role: Common-mode TVS array element (paired with other SMAJ devices) suppressing differential and common-mode transients on RJ45 interface. Use Value: 20–22.1 V VBR aligns with 19 V PoE midspan operating range, allowing clean clamping before PHY IC damage threshold (~30 V). |
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/I | Same electrical specs and DO-214AC package; RoHS-compliant but not halogen-free or AEC-Q101 qualified. | Approved for commercial/industrial use only; excluded from automotive qualification programs requiring halogen-free materials. | Select when AEC-Q101 and halogen-free compliance are not required, and cost optimization is prioritized. |
| SMBJ18CAHM3/I | Higher 600 W PPPM rating, identical VWM/VBR/VC, but larger SMB (DO-214AA) package (5.28 mm × 4.57 mm vs. SMA's 5.28 mm × 4.50 mm). | Offers greater surge margin for harsher environments (e.g., railway traction control); requires PCB layout revision due to wider body. | Choose when system-level surge testing exceeds 400 W requirements and board space allows SMB footprint. |
Compared with SMAJ18CAHE3/I, the SMAJ18CAHM3/I adds halogen-free construction and AEC-Q101 validation for automotive deployment; versus SMBJ18CAHM3/I, it trades 200 W peak power headroom for smaller SMA footprint and tighter board area utilization.
Availability
SMAJ18CAHM3/I is available at Aetrix Electronics and suitable for automotive sensor modules, industrial PLC I/O cards, consumer USB peripherals, and telecom line interface designs requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SMAJ18CAHM3/I 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 performance.
The SMAJ series targets high-reliability transient suppression in automotive, industrial, and communications systems - engineered for rapid clamping, low leakage, and robust surge handling in compact surface-mount packages.
FAQ
What is the clamping voltage of SMAJ18CAHM3/I at its rated peak pulse current?
The SMAJ18CAHM3/I clamps to a maximum of 29.2 V at its peak pulse current of 13.7 A (10/1000 μs waveform). This value is measured under standardized test conditions per JEDEC and ensures predictable overvoltage limiting for downstream ICs. The clamping voltage directly determines the maximum stress seen by protected circuitry during surge events, making it a critical parameter for system-level immunity validation.
Is SMAJ18CAHM3/I suitable for automotive applications?
Yes, SMAJ18CAHM3/I is AEC-Q101 qualified and specifically designated for automotive use via the HM3 suffix. It meets stress test requirements for temperature cycling, humidity, mechanical shock, and surge endurance relevant to engine control, body electronics, and ADAS subsystems. Its halogen-free, RoHS-compliant construction further satisfies OEM material declarations and sustainability mandates.
How does the bidirectional configuration of SMAJ18CAHM3/I affect its circuit placement?
The bidirectional configuration of SMAJ18CAHM3/I means it has no polarity marking and functions identically in either orientation - both terminals serve as symmetrical surge current paths. This simplifies PCB layout by eliminating cathode/anode routing constraints and enables direct placement across AC-coupled lines, differential buses (e.g., CAN, RS-485), or floating sensor outputs without directional verification.
What is the maximum steady-state power dissipation of SMAJ18CAHM3/I?
The SMAJ18CAHM3/I has a maximum steady-state power dissipation (PD) of 3.3 W at TA = 50 °C on an infinite heatsink. In practical SMT layouts using recommended 0.2" × 0.2" copper pads per terminal, derating applies per Fig. 2 - e.g., ~2.2 W at 85 °C ambient. This rating governs continuous leakage-related heating and must be validated alongside board-level thermal design for high-reliability deployments.
Does SMAJ18CAHM3/I meet any safety agency certifications?
Yes, SMAJ18CAHM3/I carries Underwriters Laboratory (UL) Recognition under file E136766 for both unidirectional and bidirectional configurations, compliant with UL 497B for signal line protectors. This certification validates its performance in surge suppression applications across consumer, industrial, and telecom equipment where third-party safety approval is mandated.
SMAJ18CAHM3/I 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/I FAQ
1.How can I place an order for SMAJ18CAHM3/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CAHM3/I 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/I reliable?
The price and inventory of SMAJ18CAHM3/I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ18CAHM3/I is usually 5 days.
3.What payment methods are accepted for SMAJ18CAHM3/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CAHM3/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CAHM3/I?
SMAJ18CAHM3/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CAHM3/I 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/I?
For technical support, including SMAJ18CAHM3/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CAHM3/I requirements.
6.How does Aetrix verify that SMAJ18CAHM3/I is sourced from the original manufacturer or authorized distributors?
All SMAJ18CAHM3/I 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/I meets industry standards.
7.What is the process for return or replacement of SMAJ18CAHM3/I?
All SMAJ18CAHM3/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CAHM3/I, 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/I part is unused and in its original packaging.
Return procedure for SMAJ18CAHM3/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ18CAHM3/I Tags
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