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Vishay General Semiconductor - Diodes Division SMAJ18CAHM3_A/I
- Part No.:
- SMAJ18CAHM3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ18CAHM3_A/I.pdf
- Description:
- TVS DIODE 18VWM 29.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,134
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Product details
Overview
SMAJ18CAHM3_A/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, 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 ≤30.0 V at 13.7 A peak surge current - deployed on signal lines and power rails in automotive sensor units and industrial control interfaces.
For engineers reviewing the SMAJ18CAHM3_A/I datasheet, SMAJ18CAHM3_A/I pinout, SMAJ18CAHM3_A/I application, or SMAJ18CAHM3_A/I equivalent, this page delivers verified electrical specs, AEC-Q101 qualification status, thermal resistance data (RθJA = 120 °C/W), clamping performance under standardized surge waveforms, and direct alternatives with documented parameter divergence.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, delivering identical clamping behavior during positive and negative transients. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1.0 μA at VWM), while the SMA package supports automated SMT placement and meets MSL Level 1 reflow requirements (peak 260 °C).
The device complies with ANSI/IEEE C62.35 surge standards and is rated for repetitive 10/1000 μs pulses at 0.01% duty cycle. With a maximum junction temperature of +150 °C and thermal resistance of 30 °C/W (junction-to-lead), it sustains high-energy surges when mounted on recommended 5.0 mm × 5.0 mm copper pads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 18 V - Maximum continuous reverse operating voltage before conduction begins; defines safe operating margin for 15–18 V nominal supply/signal lines. |
| VBR (min/max) | 20.0 V / 22.1 V at IT = 1 mA - Confirmed breakdown threshold range; ensures reliable triggering above system operating voltage. |
| VC @ IPPM | 30.0 V at 13.7 A - Clamped voltage during 400 W surge; limits downstream IC stress to sub-30 V during lightning or ESD events. |
| PPPM | 400 W (10/1000 μs) - Peak surge power handling; sufficient for ISO 7637-2 Pulse 1/2a/5a and IEC 61000-4-5 Level 3 compliance. |
| IPPM | 13.7 A - Peak surge current capability; validated with standard 10/1000 μs waveform per Fig. 1 in datasheet 88390. |
| TJmax | +150 °C - Maximum junction temperature; enables operation in under-hood automotive environments and industrial enclosures. |
| RθJA | 120 °C/W - Junction-to-ambient thermal resistance; requires minimum 5.0 mm × 5.0 mm copper pad area per terminal for full power rating. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, bidirectional configuration with no polarity marking. Matte tin-plated leads, RoHS-compliant and halogen-free (HM3 suffix), qualified to JESD 201 Class 2 whisker test.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient return path (bidirectional) | Common terminal for symmetrical clamping; connects to protected line or ground reference depending on layout. |
| Cathode | Transient return path (bidirectional) | Electrically identical to Anode in CA devices; no functional distinction - forms dual-junction structure enabling bidirectional conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Identical VBR, VC, and IPPM in both directions - eliminates need for polarity-aware routing in differential or AC-coupled signal protection. |
| AEC-Q101 qualification | Validated for automotive-grade reliability (HM3 suffix); includes temperature cycling, HTRB, and surge endurance testing per stress test plan. |
| Low clamping ratio | VC/VWM = 30.0/18 ≈ 1.67 - tighter than typical 2.0+ ratio; reduces voltage overshoot on protected ICs during fast transients. |
| MSL Level 1 compatibility | Reflow-safe up to 260 °C peak - supports single-pass lead-free assembly without moisture-induced damage or delamination. |
| Glass passivated junction | Stable leakage (<1.0 μA at VWM) and breakdown tolerance over life - critical for long-term reliability in unattended industrial systems. |
Applications
| Automotive Sensor Interface Protection | Industrial CAN Bus Line Protection |
|---|---|
|
Use Scenario: Protecting LIN/CAN transceiver inputs and outputs against load dump, jump-start, and inductive switching transients in engine control modules. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed directly at connector entry point, shunting surge energy to chassis ground before reaching PHY layer. Use Value: Limits transient voltage to ≤30.0 V, preventing latch-up or gate oxide damage in 3.3 V/5 V transceivers while maintaining signal integrity during normal operation. |
Use Scenario: Safeguarding RS-485 and CAN FD physical layer circuits in programmable logic controllers (PLCs) exposed to factory floor EMI and relay coil kickback. IC Role / Device Role / Timing Role: Low-capacitance (≈150 pF at 0 V) TVS placed differential across bus lines (CAN_H/CAN_L) to suppress common-mode surges without distorting 1 Mbps+ signaling. Use Value: Maintains <1.0 μA leakage at 18 V standby, avoiding false triggering or bus bias shift; clamps 400 W surges within 1 ns response time. |
| Consumer Power Adapter Input Stage | Telecom DSL Line Surge Suppression |
|
Use Scenario: Secondary-side overvoltage protection on 12–19 V DC output rails of wall adapters and USB-C PD chargers subjected to capacitor discharge events. IC Role / Device Role / Timing Role: Standoff-rated clamp between VOUT and GND, activated only during fault conditions exceeding 18 V, preserving regulation loop stability. Use Value: Delivers 400 W surge immunity without derating below 78 V - matches adapter output voltage envelope and avoids premature conduction during ripple. |
Use Scenario: Primary protection for ADSL/VDSL line interface ICs against lightning-induced surges entering via telephone wiring in residential gateways. IC Role / Device Role / Timing Role: First-stage protector located before hybrid transformer and line driver, absorbing >1 kV/10/700 μs surges per ITU-T K.21. Use Value: Withstands repeated 13.7 A surges at 30.0 V clamp, reducing stress on downstream MOVs and silicon-based secondary protectors. |
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_A/I | Same electrical specs, but RoHS-compliant commercial grade (E3) without halogen-free certification or AEC-Q101 qualification. | Lacks automotive qualification and whisker-test compliance; suitable for consumer/industrial non-automotive use only. | Select SMAJ18CAHE3_A/I if AEC-Q101 and halogen-free requirements are not mandated, and cost optimization is prioritized. |
| SMBJ18CAHM3_A/I | Same VWM/VBR/VC, but higher 600 W PPPM rating and SMB (DO-214AA) package (larger footprint, lower RθJA = 80 °C/W). | Requires PCB layout change due to larger 4.58 mm × 3.94 mm body vs. SMA's 4.50 mm × 2.79 mm; better for high-reliability industrial power rails. | Choose SMBJ18CAHM3_A/I when surge energy exceeds 400 W or thermal management demands lower junction rise under sustained surges. |
Compared with SMAJ18CAHM3_A/I, SMAJ18CAHE3_A/I omits automotive qualification and halogen-free compliance, while SMBJ18CAHM3_A/I trades compact size for higher surge capacity and improved thermal performance - selection depends strictly on qualification mandates and board space constraints.
Availability
SMAJ18CAHM3_A/I is available at Aetrix Electronics and suitable for automotive sensor modules, industrial PLC I/O protection, and telecom line interface designs requiring stable component supply with AEC-Q101 validation and halogen-free compliance.
Supply support for SMAJ18CAHM3_A/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, 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 telecom infrastructure - engineered for rapid response, low clamping, and robust surge endurance in harsh environments.
FAQ
What is the clamping voltage of SMAJ18CAHM3_A/I at its rated peak pulse current?
The SMAJ18CAHM3_A/I clamps to a maximum of 30.0 V at its peak pulse current of 13.7 A (10/1000 μs waveform). This value is measured per Figure 1 in Vishay datasheet 88390 and reflects worst-case device variation under standardized surge conditions. The clamping voltage ensures protected circuitry remains below critical thresholds during transient events, and SMAJ18CAHM3_A/I maintains this performance across its full operating temperature range.
Is SMAJ18CAHM3_A/I qualified for automotive applications?
Yes, SMAJ18CAHM3_A/I is AEC-Q101 qualified, as confirmed by the HM3 suffix and documentation in Vishay's ordering information table (page 3, datasheet 88390). This qualification covers stress tests including temperature cycling, high-temperature reverse bias, and surge endurance - validating its suitability for under-hood and chassis-mounted automotive electronics. SMAJ18CAHM3_A/I meets these requirements without derating.
What does the "CA" suffix indicate in SMAJ18CAHM3_A/I?
The "CA" suffix in SMAJ18CAHM3_A/I denotes a bidirectional transient voltage suppressor configuration. Unlike unidirectional variants (e.g., SMAJ18A), SMAJ18CAHM3_A/I provides symmetrical clamping in both polarities, making it ideal for protecting AC-coupled signals, differential buses like CAN or RS-485, and any application where voltage transients may occur with either polarity. No cathode band marking is present on SMAJ18CAHM3_A/I.
What is the thermal resistance of SMAJ18CAHM3_A/I, and how does it affect layout?
SMAJ18CAHM3_A/I has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W when mounted on the recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes standard JEDEC test conditions; inadequate copper area will increase junction temperature and reduce surge capability. To sustain full 400 W rating, SMAJ18CAHM3_A/I must be routed with minimum pad dimensions and avoid thermal isolation - undersized traces degrade SMAJ18CAHM3_A/I's surge endurance.
How does SMAJ18CAHM3_A/I differ from SMAJ18A in practical design?
SMAJ18CAHM3_A/I is bidirectional with symmetrical VBR, VC, and leakage in both directions, whereas SMAJ18A is unidirectional and features a cathode band for polarity-sensitive placement. SMAJ18CAHM3_A/I eliminates orientation concerns in differential or AC signal paths and supports ground-referenced or floating clamping configurations. SMAJ18A offers slightly lower VF (3.5 V at 25 A) but cannot suppress negative transients - SMAJ18CAHM3_A/I is mandatory for full bidirectional protection.
SMAJ18CAHM3_A/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:
- 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/I FAQ
1.How can I place an order for SMAJ18CAHM3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ18CAHM3_A/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_A/I reliable?
The price and inventory of SMAJ18CAHM3_A/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_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ18CAHM3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ18CAHM3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ18CAHM3_A/I?
SMAJ18CAHM3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ18CAHM3_A/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_A/I?
For technical support, including SMAJ18CAHM3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ18CAHM3_A/I requirements.
6.How does Aetrix verify that SMAJ18CAHM3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ18CAHM3_A/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_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ18CAHM3_A/I?
All SMAJ18CAHM3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ18CAHM3_A/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_A/I part is unused and in its original packaging.
Return procedure for SMAJ18CAHM3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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