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Vishay General Semiconductor - Diodes Division SMAJ20CAHM3/H
- Part No.:
- SMAJ20CAHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ20CAHM3/H.pdf
- Description:
- TVS DIODE 20VWM 32.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:5,129
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Product details
Overview
SMAJ20CAHM3/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 20 V standoff 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 rating with 10/1000 μs waveform - used to protect MOSFETs, ICs, and sensor interfaces in automotive and industrial control systems.
For engineers reviewing the SMAJ20CAHM3/H datasheet, SMAJ20CAHM3/H pinout, SMAJ20CAHM3/H application, or SMAJ20CAHM3/H equivalent, key selection criteria include bidirectional clamping capability, AEC-Q101 qualification, halogen-free RoHS compliance, low clamping ratio (VC/VWM ≈ 1.62), and compatibility with automated SMT assembly on standard PCB pad layouts.
Technical Context
This TVS diode operates symmetrically in both directions due to its bidirectional construction, enabling protection of AC-coupled or differential signal paths without polarity sensitivity. Its glass-passivated junction ensures stable breakdown characteristics and low leakage (<1.0 μA at VWM), while the low incremental surge resistance supports fast energy diversion during ESD or lightning-induced surges.
The device is rated for repetitive 10/1000 μs transients at 0.01% duty cycle (400 W up to 78 V; derated to 300 W above), with thermal resistance RθJA = 120 °C/W and RθJL = 30 °C/W - confirming suitability for compact layouts with limited copper area, provided minimum 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal are used.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 20 V - maximum continuous reverse operating voltage before clamping begins; defines safe operating margin for 24 V nominal systems. |
| VBR min/max | 22.2 V / 24.5 V at IT = 1 mA - tight breakdown window ensures predictable turn-on across temperature and unit variation. |
| VC @ IPPM | 32.4 V at 12.3 A - clamping voltage limits downstream component stress during 400 W transient events. |
| PPPM | 400 W (10/1000 μs) - peak surge handling capacity for common industrial and automotive load-switching transients. |
| ID @ VWM | <1.0 μA - ultra-low leakage preserves signal integrity and battery life in always-on sensor circuits. |
| TJ max | +150 °C - enables operation in under-hood automotive environments and high-ambient industrial enclosures. |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline compatible with J-STD-020 MSL Level 1 reflow profiles (260 °C peak). |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads; bidirectional symmetry means no polarity marking - terminals are electrically identical and interchangeable.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Transient conduction path | Both terminals serve as bidirectional surge current entry/exit points; no cathode band marking required. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD robustness - suitable for engine control, ADAS, and infotainment modules. |
| Halogen-free & RoHS-compliant (HM3 suffix) | Meets IEC 61249-2-21 and JEDEC J-STD-20D requirements - supports green manufacturing and end-of-life compliance. |
| 400 W peak pulse power (10/1000 μs) | Handles typical ISO 7637-2 Pulse 1/2a/5a transients without degradation - eliminates need for external series impedance in many 12/24 V systems. |
| Low clamping ratio (VC/VWM = 1.62) | Minimizes overvoltage exposure to protected ICs - critical for safeguarding 3.3 V or 5 V logic interfacing with higher-voltage domains. |
| MSL Level 1 moisture sensitivity | Allows unlimited floor life and single-reflow processing without baking - reduces production overhead in high-volume SMT lines. |
Applications
| Automotive Power Line Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting LIN bus transceivers and microcontroller I/O pins from load-dump and jump-start transients in 12 V vehicle electrical systems. IC Role / Device Role / Timing Role: Bidirectional clamping element placed between power rail and ground, responding within <1 ns to suppress spikes exceeding 20 V. Use Value: Enables direct connection of 24 V-rated sensors to 3.3 V MCU inputs without level-shifting circuitry, leveraging 32.4 V VC to stay below absolute maximum ratings. |
Use Scenario: Safeguarding analog outputs of pressure/temperature transducers connected to PLC analog input modules in factory automation. IC Role / Device Role / Timing Role: Parallel-connected transient shunt on 4–20 mA loop wiring, activated only during fault conditions to clamp induced surges. Use Value: Prevents false triggering and ADC saturation during EFT bursts (IEC 61000-4-4) by limiting voltage excursion to ≤32.4 V at full rated surge current. |
| Consumer USB Port ESD Protection | Telecom DSL Line Surge Suppression |
Use Scenario: Secondary-level protection on VBUS and D+/D− lines of USB 2.0 ports in set-top boxes and smart displays exposed to human-body-model (HBM) ESD. IC Role / Device Role / Timing Role: Fast-response voltage clamp placed after primary polymer PTC, absorbing residual 8 kV contact discharge energy. Use Value: Achieves IEC 61000-4-2 Level 4 compliance (±8 kV contact) with sub-1 ns response and <1 μA leakage - preserving signal integrity at 480 Mbps. |
Use Scenario: Front-end surge suppression on twisted-pair DSL lines entering residential gateways, subjected to lightning-induced common-mode transients. IC Role / Device Role / Timing Role: Bidirectional line-to-line and line-to-ground protector mounted at board edge, sharing surge current between pairs. Use Value: Withstands 10/1000 μs surges up to 400 W while maintaining <1 pF junction capacitance - avoids signal attenuation in ADSL2+ frequency bands (up to 2.2 MHz). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20CAHE3/H | Same electrical specs and package, but RoHS-compliant without halogen-free certification (E3 vs HM3). | Approved for commercial/industrial use; not qualified for automotive AEC-Q101. | Select when halogen-free requirement is absent and automotive qualification is unnecessary. |
| SMBJ20CAHM3 | Same VWM/VC/PPPM, but SMB (DO-214AA) package - 2.54 mm lead pitch vs SMA's 3.99 mm; 600 W peak power rating. | Higher power handling and slightly lower thermal resistance (RθJA = 80 °C/W), but larger footprint. | Choose when system-level surge threat exceeds 400 W or board layout allows larger package for improved margin. |
Compared with SMAJ20CAHM3/H, SMAJ20CAHE3/H lacks halogen-free and AEC-Q101 validation, while SMBJ20CAHM3 offers higher surge capacity in a physically larger package - making SMAJ20CAHM3/H optimal for space-constrained automotive modules requiring full compliance.
Availability
SMAJ20CAHM3/H is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor interfaces, consumer USB power delivery, and telecom line protection requiring stable component supply and long-term lifecycle support.
Supply support for SMAJ20CAHM3/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, rectifiers, MOSFETs, and protection devices with emphasis on reliability, efficiency, and application-specific optimization.
The SMAJ series is engineered for robust transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where consistent clamping performance and AEC-Q101 validation are mandatory.
FAQ
What does the 'HM3' suffix indicate in SMAJ20CAHM3/H?
The 'HM3' suffix in SMAJ20CAHM3/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. It confirms compliance with JEDEC J-STD-20D MSL Level 1, matte tin plating per J-STD-002, and whisker resistance per JESD 201 Class 2 - making SMAJ20CAHM3/H suitable for automotive under-hood deployment and green manufacturing requirements.
Is SMAJ20CAHM3/H unidirectional or bidirectional?
SMAJ20CAHM3/H is a bidirectional TVS diode, as indicated by the 'CA' suffix. Its symmetrical breakdown behavior allows it to clamp voltage transients equally in both polarities - ideal for protecting AC-coupled signals, differential buses like CAN or RS-485, and power rails where polarity reversal may occur. No cathode marking is present on the SMA package.
What is the maximum clamping voltage of SMAJ20CAHM3/H at rated surge current?
The maximum clamping voltage (VC) of SMAJ20CAHM3/H is 32.4 V at 12.3 A peak pulse current (IPPM), measured under the standardized 10/1000 μs waveform. This value ensures protected downstream components - such as 3.3 V or 5 V MCUs - remain within their absolute maximum voltage ratings during transient events, given the 20 V standoff voltage (VWM).
Can SMAJ20CAHM3/H replace SMAJ20A in a design?
No - SMAJ20CAHM3/H is bidirectional, while SMAJ20A is unidirectional. Substituting SMAJ20CAHM3/H for SMAJ20A would eliminate polarity-sensitive protection and could compromise circuit behavior in DC-biased applications. SMAJ20CAHM3/H is only a functional replacement for other 'CA' variants (e.g., SMAJ20CAHE3/H); pin-compatible alternatives must share the same CA designation and voltage grade.
What PCB pad layout is recommended for optimal thermal performance of SMAJ20CAHM3/H?
Vishay specifies a minimum 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pad for each terminal of SMAJ20CAHM3/H to achieve rated 400 W peak pulse power. Using smaller pads reduces thermal dissipation capability and may cause premature failure during repetitive surges. The SMA (DO-214AC) outline drawing confirms 3.99 mm terminal spacing, requiring precise stencil aperture design for reliable solder joint formation.
SMAJ20CAHM3/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):
- 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/H FAQ
1.How can I place an order for SMAJ20CAHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ20CAHM3/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 SMAJ20CAHM3/H reliable?
The price and inventory of SMAJ20CAHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ20CAHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ20CAHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ20CAHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ20CAHM3/H?
SMAJ20CAHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ20CAHM3/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 SMAJ20CAHM3/H?
For technical support, including SMAJ20CAHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ20CAHM3/H requirements.
6.How does Aetrix verify that SMAJ20CAHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ20CAHM3/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 SMAJ20CAHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ20CAHM3/H?
All SMAJ20CAHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ20CAHM3/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 SMAJ20CAHM3/H part is unused and in its original packaging.
Return procedure for SMAJ20CAHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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