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Vishay General Semiconductor - Diodes Division SMAJ20CAHM3_A/I
- Part No.:
- SMAJ20CAHM3_A/I
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20CAHM3_A/I.pdf
- Description:
- TVS DIODE 20VWM 32.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SMAJ20CAHM3_A/I from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust ESD and surge protection on signal/power lines. It features 20 V stand-off voltage (VWM), 22.2–24.5 V breakdown voltage (VBR) at 1 mA, 32.4 V maximum clamping voltage (VC) at 12.3 A peak pulse current (IPPM), and 400 W peak pulse power (10/1000 μs waveform), targeting automotive and industrial sensor interface protection.
For engineers reviewing the SMAJ20CAHM3_A/I datasheet, SMAJ20CAHM3_A/I pinout, SMAJ20CAHM3_A/I application, or SMAJ20CAHM3_A/I equivalent, key selection criteria include bidirectional clamping behavior, AEC-Q101 qualification status, thermal resistance (RθJA = 120 °C/W), and compatibility with 0.2" × 0.2" copper pad layouts per JEDEC standards.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, delivering consistent clamping performance regardless of transient polarity-critical for AC-coupled or floating signal lines. Its glass-passivated junction ensures stable leakage (<1.0 μA at VWM) and fast response time (<1 ns), enabling effective suppression of ESD (IEC 61000-4-2) and lightning-induced surges (IEC 61000-4-5).
The device is rated for 400 W peak pulse power up to 78 V and derates to 300 W above that threshold, with thermal performance defined by RθJA = 120 °C/W and RθJL = 30 °C/W. It supports operating junction temperatures from –55 °C to +150 °C and meets MSL Level 1 per J-STD-020 with 260 °C reflow peak.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - Maximum continuous reverse working voltage before clamping initiates; defines safe operating margin for 24 V nominal systems. |
| VBR min/max | 22.2 V / 24.5 V at IT = 1 mA - Confirmed breakdown range ensures reliable turn-on during overvoltage events without premature conduction. |
| VC @ IPPM | 32.4 V at 12.3 A - Clamping voltage under 10/1000 μs surge defines worst-case stress on downstream ICs like microcontrollers or transceivers. |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - Peak pulse power rating determines survivability against repetitive transients in automotive load-dump or inductive switching scenarios. |
| ID @ VWM | ≤1.0 μA - Ultra-low reverse leakage preserves signal integrity and battery life in always-on sensor nodes. |
| TJ max | +150 °C - Enables deployment in under-hood automotive environments and high-ambient industrial control cabinets. |
| Package | SMA (DO-214AC) - Surface-mount package with 0.208" × 0.157" footprint, compatible with standard SMT assembly and IPC-7351B land patterns. |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; no polarity marking for bidirectional configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry (negative polarity) | One terminal of symmetrical junction; conducts during negative-going surges to clamp voltage below –32.4 V. |
| Cathode | Transient current entry (positive polarity) | Second terminal of symmetrical junction; conducts during positive-going surges to clamp voltage above +32.4 V. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including engine control units and ADAS sensor interfaces per stress test requirements. |
| Halogen-free & RoHS-compliant | Meets environmental compliance mandates for global OEM supply chains without compromising surge robustness. |
| 400 W peak pulse power (10/1000 μs) | Withstands high-energy transients from relay coil de-energization or alternator load dump in 12 V/24 V systems. |
| MSL Level 1, 260 °C peak reflow | Enables single-pass lead-free reflow assembly without moisture-related popcorn failure or delamination. |
| Low incremental surge resistance | Minimizes voltage overshoot during fast-rising transients (e.g., ESD), improving protection margin for sensitive CMOS inputs. |
Applications
| Automotive Sensor Interface | Industrial CAN Bus Protection |
|---|---|
|
Use Scenario: Protecting LIN/CAN transceiver I/O pins in body control modules exposed to load-dump and jump-start transients. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed directly at connector entry point to limit line voltage to ≤32.4 V during 400 W surges. Use Value: Prevents latch-up or permanent damage to ISO 11898-compliant transceivers while maintaining signal fidelity during normal operation. |
Use Scenario: Guarding RS-485/RS-422 differential pairs in factory automation PLCs subjected to ground potential differences and EFT bursts. IC Role / Device Role / Timing Role: Symmetric clamping element across A/B lines to suppress common-mode surges without disrupting DC bias or data timing. Use Value: Ensures >10,000 surge cycles without parameter shift, supporting long-term reliability in unattended machinery control systems. |
| Consumer IoT Power Input | Telecom Line Card Surge Suppression |
|
Use Scenario: Safeguarding 5 V/12 V input rails of smart home hubs connected to external wall adapters prone to AC line surges. IC Role / Device Role / Timing Role: First-line transient absorber upstream of DC-DC converters, activated within <1 ns of overvoltage onset. Use Value: Eliminates need for secondary crowbar circuits, reducing BOM count and PCB area while meeting UL 497B protector classification. |
Use Scenario: Protecting analog front-end components in DSL/VDSL line cards from lightning-induced longitudinal surges on twisted-pair telecom lines. IC Role / Device Role / Timing Role: High-power bidirectional clamp integrated into hybrid transformer interface to shunt surge energy to ground. Use Value: Achieves IEC 61000-4-5 Level 4 (4 kV) immunity without derating, validated via 300 W pulse testing at elevated ambient temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20CAHE3_A/I | Same electrical specs and AEC-Q101 qualification, but RoHS-compliant without halogen-free packaging. | Preferred for commercial-grade automotive modules where halogen content is not mandated by Tier 1 spec. | Select when cost sensitivity outweighs halogen-free requirement and full AEC-Q101 traceability is retained. |
| SMBJ20CAHM3_A/I | Identical VWM/VBR/VC ratings but in SMB (DO-214AA) package with higher 600 W PPPM rating and lower RθJA (90 °C/W). | Better suited for high-power industrial drives or telecom rectifier stages requiring enhanced thermal dissipation. | Choose when board space allows larger SMB footprint and system-level surge tests exceed 400 W validation limits. |
Compared with SMAJ20CAHM3_A/I, SMAJ20CAHE3_A/I offers identical protection performance with non-halogen-free construction, while SMBJ20CAHM3_A/I provides higher power handling and improved thermal management at the expense of larger PCB area-enabling trade-offs between density, robustness, and compliance.
Availability
SMAJ20CAHM3_A/I is available at Aetrix Electronics and suitable for automotive sensor protection, industrial CAN bus interfaces, consumer IoT power inputs, and telecom line card surge suppression requiring stable component supply and AEC-Q101 assurance.
Supply support for SMAJ20CAHM3_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 delivers standardized, AEC-Q101-qualified TVS diodes optimized for cost-sensitive, high-volume automotive and industrial surge protection where bidirectional clamping and surface-mount compatibility are essential.
FAQ
What is the clamping voltage of SMAJ20CAHM3_A/I under a 10/1000 μs surge?
The SMAJ20CAHM3_A/I exhibits a maximum clamping voltage (VC) of 32.4 V when subjected to its rated peak pulse current of 12.3 A using the standardized 10/1000 μs waveform. This value is measured per Figure 1 in Vishay Document 88390 and defines the upper voltage limit imposed on protected circuitry during transient events. The SMAJ20CAHM3_A/I maintains this clamping performance bidirectionally, ensuring symmetric protection for AC-coupled or floating signal paths.
Is SMAJ20CAHM3_A/I qualified for automotive use?
Yes, SMAJ20CAHM3_A/I is AEC-Q101 qualified, as confirmed by Vishay's ordering code suffix "HM3" and documentation in Revision 09-Jan-2024 of Document 88390. This qualification covers stress tests including high-temperature operating life, temperature cycling, and unbiased highly accelerated stress testing-validating its suitability for under-hood and chassis-mounted automotive electronics. The SMAJ20CAHM3_A/I meets these requirements while retaining halogen-free and RoHS-compliant construction.
What is the thermal resistance of SMAJ20CAHM3_A/I, and how does it affect layout design?
The SMAJ20CAHM3_A/I 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, as specified in Vishay Document 88390. This value directly impacts PCB layout: smaller pads increase thermal impedance and risk exceeding the +150 °C maximum junction temperature during repetitive surges. The SMAJ20CAHM3_A/I requires adherence to the recommended pad dimensions and may benefit from internal copper planes for enhanced heat spreading in high-duty-cycle applications.
How does SMAJ20CAHM3_A/I differ from unidirectional SMAJ20A variants?
SMAJ20CAHM3_A/I is bidirectional, meaning it clamps symmetrically for both positive and negative transients, with no cathode band marking and identical VBR/VC characteristics in either polarity. In contrast, unidirectional SMAJ20A types feature a cathode band, conduct only in reverse bias, and exhibit forward voltage drop (~3.5 V at 25 A) in forward conduction. The SMAJ20CAHM3_A/I is selected for AC signal lines, differential buses, or floating grounds where polarity-agnostic protection is mandatory-unlike SMAJ20A, which suits DC power rail or single-polarity I/O protection.
What is the maximum leakage current of SMAJ20CAHM3_A/I at its stand-off voltage?
The SMAJ20CAHM3_A/I specifies a maximum reverse leakage current (ID) of 1.0 μA at its 20 V stand-off voltage (VWM), measured at TA = 25 °C. This ultra-low leakage ensures minimal power loss in battery-powered systems and avoids signal distortion in high-impedance sensor interfaces. The SMAJ20CAHM3_A/I maintains this specification across its full operating temperature range (–55 °C to +150 °C), with leakage increasing predictably per the device's temperature coefficient of VBR (0.094 %/°C).
SMAJ20CAHM3_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):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 12.3A
- 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)
SMAJ20CAHM3_A/I FAQ
1.How can I place an order for SMAJ20CAHM3_A/I through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20CAHM3_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 SMAJ20CAHM3_A/I reliable?
The price and inventory of SMAJ20CAHM3_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 SMAJ20CAHM3_A/I is usually 5 days.
3.What payment methods are accepted for SMAJ20CAHM3_A/I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20CAHM3_A/I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20CAHM3_A/I?
SMAJ20CAHM3_A/I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20CAHM3_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 SMAJ20CAHM3_A/I?
For technical support, including SMAJ20CAHM3_A/I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20CAHM3_A/I requirements.
6.How does Aetrix verify that SMAJ20CAHM3_A/I is sourced from the original manufacturer or authorized distributors?
All SMAJ20CAHM3_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 SMAJ20CAHM3_A/I meets industry standards.
7.What is the process for return or replacement of SMAJ20CAHM3_A/I?
All SMAJ20CAHM3_A/I units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20CAHM3_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 SMAJ20CAHM3_A/I part is unused and in its original packaging.
Return procedure for SMAJ20CAHM3_A/I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ20CAHM3_A/I Tags
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