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Vishay General Semiconductor - Diodes Division SMAJ51CAHM3/H
- Part No.:
- SMAJ51CAHM3/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51CAHM3/H.pdf
- Description:
- TVS DIODE 51VWM 82.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:2,564
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Product details
Overview
SMAJ51CAHM3/H 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 51 V standoff voltage (VWM), 56.7–62.7 V breakdown voltage (VBR) at 1 mA, 82.4 V maximum clamping voltage (VC) at 4.9 A peak pulse current, and 400 W peak pulse power rating (10/1000 μs waveform). It is widely deployed to protect MOSFETs, ICs, and sensor signal lines in automotive and industrial power supply interfaces.
For engineers reviewing the SMAJ51CAHM3/H datasheet, SMAJ51CAHM3/H pinout, SMAJ51CAHM3/H application, or SMAJ51CAHM3/H equivalent, this device serves as a halogen-free, AEC-Q101-qualified TVS for bidirectional surge suppression in space-constrained PCB layouts requiring reliable ESD and lightning transient immunity per IEC 61000-4-2/4-5.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, with identical electrical characteristics in forward and reverse directions. Its glass-passivated junction enables fast response time (<1 ps) and low incremental surge resistance, ensuring effective clamping during sub-microsecond transients induced by inductive switching or EFT bursts.
The device is rated for continuous operation from –55 °C to +150 °C junction temperature, with thermal resistance of 120 °C/W (junction-to-ambient) and 30 °C/W (junction-to-lead). It meets MSL Level 1 per J-STD-020 and is qualified to AEC-Q101 for automotive under-hood applications when ordered with HM3 suffix.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM (Stand-off Voltage) | 51 V - Maximum continuous reverse voltage before significant leakage; defines operating margin below clamping threshold. |
| VBR (Breakdown Voltage) | 56.7–62.7 V at 1 mA - Voltage at which device enters avalanche conduction; ensures predictable turn-on during overvoltage events. |
| VC (Clamping Voltage) | 82.4 V at 4.9 A (10/1000 μs) - Peak voltage seen by protected circuit during surge; determines safe stress level for downstream components. |
| PPPM (Peak Pulse Power) | 400 W - Sustained energy absorption capability for standard lightning surge waveforms; derates to 300 W above 78 V. |
| IPPM (Peak Pulse Current) | 4.9 A - Maximum non-repetitive surge current the device can safely divert without degradation. |
| Leakage Current (ID) | 1.0 μA max at 51 V - Minimal standby power loss and signal integrity impact in high-impedance circuits. |
| TJ Max | +150 °C - Enables use in under-hood automotive environments and thermally demanding industrial enclosures. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, halogen-free, RoHS-compliant, MSL Level 1, matte tin-plated leads. Dimensions: 4.50 mm × 2.79 mm × 2.29 mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal in forward bias; symmetrical with cathode in bidirectional operation | No polarity marking on device body; terminals are functionally interchangeable for AC or differential line protection. |
| Cathode | Current exit terminal in forward bias; symmetrical with anode in bidirectional operation | Device conducts identically in either direction - essential for protecting balanced signal pairs or AC power rails. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional symmetry | Identical VBR, VC, and IPPM in both directions - eliminates need for polarity-aware layout in differential or AC-coupled protection. |
| AEC-Q101 qualification | Validated for automotive-grade reliability including temperature cycling, humidity testing, and surge endurance - supports Tier-1 module designs. |
| Halogen-free & RoHS-compliant (HM3) | Meets global environmental compliance requirements without compromising surge robustness or thermal performance. |
| Low-profile SMA package | 0.208" × 0.177" footprint with 0.090" height - enables dense placement near connectors or IC power pins without interfering with mechanical shields. |
| 400 W peak pulse power (10/1000 μs) | Withstands IEC 61000-4-5 Level 4 surges (4 kV line-earth, 2 kV line-line) when properly mounted on 5 mm × 5 mm copper pads. |
Applications
| Automotive Power Rail Protection | Industrial Sensor Signal Line Guarding |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump and alternator ripple transients. IC Role / Device Role / Timing Role: Bidirectional shunt clamp placed between power rail and ground to limit voltage excursions to <83 V. Use Value: Prevents latch-up or gate oxide damage in microcontrollers and CAN transceivers during ISO 7637-2 Pulse 5a events. |
Use Scenario: Shielding analog outputs (e.g., 4–20 mA loops) from ESD and cable discharge events in factory automation. IC Role / Device Role / Timing Role: Low-capacitance (≈100 pF) bidirectional clamp across signal and return lines. Use Value: Maintains signal fidelity while suppressing ±8 kV contact ESD per IEC 61000-4-2 without adding propagation delay. |
| Telecom DC Power Input Stage | Consumer USB Port Surge Suppression |
Use Scenario: Safeguarding PoE-powered equipment inputs against lightning-induced surges on 48 V DC lines. IC Role / Device Role / Timing Role: Primary-level TVS upstream of DC-DC converters and hot-swap controllers. Use Value: Absorbs up to 400 W of transient energy, reducing stress on secondary-stage protection and enabling smaller downstream components. |
Use Scenario: Adding robustness to USB Type-A/C VBUS lines against accidental 12 V adapter misconnection or ESD. IC Role / Device Role / Timing Role: Standoff-rated clamp (51 V) that remains inactive during normal 5 V operation but activates instantly at >62 V. Use Value: Prevents damage to USB controller ICs and power switches without affecting enumeration speed or voltage regulation accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51CAHE3/H | Same electrical specs and package, but RoHS-compliant commercial grade (not halogen-free); no AEC-Q101 qualification. | Suitable for non-automotive industrial or consumer applications where halogen-free requirement is not mandated. | Select HE3/H if cost sensitivity outweighs halogen-free compliance or automotive qualification needs. |
| SMBJ51CAHM3 | Same VWM/VC ratings but in larger SMB (DO-214AA) package; 600 W PPPM rating; higher thermal mass. | Better suited for higher-energy surge environments (e.g., outdoor telecom cabinets) where board space allows larger footprint. | Choose SMBJ51CAHM3 when surge energy exceeds 400 W or long-term thermal cycling demands lower RθJA. |
Compared with SMAJ51CAHM3/H, SMAJ51CAHE3/H lacks halogen-free certification and automotive qualification but offers identical clamping performance in a lower-cost variant; SMBJ51CAHM3 delivers higher surge capacity and thermal resilience at the expense of 30% larger PCB area and different pad layout.
Availability
SMAJ51CAHM3/H is available at Aetrix Electronics and suitable for automotive control units, industrial sensor interfaces, telecom power supplies, and consumer USB protection requiring stable component supply with full traceability and lifecycle management.
Supply support for SMAJ51CAHM3/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 was engineered for high-reliability transient suppression in space-constrained, thermally demanding environments - particularly targeting automotive, industrial, and telecom systems needing AEC-Q101-qualified, halogen-free TVS solutions.
FAQ
What does the 'HM3' suffix indicate in SMAJ51CAHM3/H?
The 'HM3' suffix in SMAJ51CAHM3/H denotes halogen-free, RoHS-compliant construction with AEC-Q101 qualification. It confirms compliance with automotive reliability standards and environmental regulations, distinguishing it from commercial-grade variants like HE3/H. This makes SMAJ51CAHM3/H appropriate for under-hood automotive modules and green-certified industrial equipment where material content and long-term field reliability are critical.
How does SMAJ51CAHM3/H differ from unidirectional SMAJ51A variants?
SMAJ51CAHM3/H is bidirectional, meaning it provides symmetrical clamping in both polarities - ideal for AC lines, differential signals, or floating grounds. In contrast, unidirectional SMAJ51A has a defined cathode band and only clamps in reverse bias; forward conduction behaves like a standard diode. SMAJ51CAHM3/H's bidirectional nature eliminates polarity concerns during placement and supports protection of balanced interfaces without additional circuitry.
What is the maximum clamping voltage of SMAJ51CAHM3/H at its rated peak pulse current?
The maximum clamping voltage (VC) of SMAJ51CAHM3/H is 82.4 V at 4.9 A peak pulse current (10/1000 μs waveform), as specified in the Vishay datasheet. This value represents the worst-case voltage imposed on the protected circuit during a standardized surge event and must be verified against the absolute maximum ratings of downstream components to ensure safe operation.
Can SMAJ51CAHM3/H be used in place of SMAJ48CAHM3/H or SMAJ54CAHM3/H?
SMAJ51CAHM3/H is not a direct replacement for SMAJ48CAHM3/H or SMAJ54CAHM3/H due to differences in standoff voltage (VWM = 51 V vs. 48 V or 54 V) and corresponding clamping behavior. Substituting requires verifying that the 51 V VWM maintains adequate margin above system operating voltage and that the 82.4 V VC stays within the protected IC's absolute maximum rating - especially critical in 48 V automotive or industrial systems.
What PCB layout practices maximize surge handling for SMAJ51CAHM3/H?
To maximize surge handling, mount SMAJ51CAHM3/H with minimum 5.0 mm × 5.0 mm copper pads per terminal (per Vishay recommendation), use short, wide traces to minimize inductance, and avoid vias in the main current path. Thermal relief should be minimized to enhance heat dissipation, and grounding must connect directly to solid ground plane. These practices ensure the device achieves its rated 400 W peak pulse power and prevents localized overheating during repetitive transients.
SMAJ51CAHM3/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):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 4.9A
- 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)
SMAJ51CAHM3/H FAQ
1.How can I place an order for SMAJ51CAHM3/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51CAHM3/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 SMAJ51CAHM3/H reliable?
The price and inventory of SMAJ51CAHM3/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51CAHM3/H is usually 5 days.
3.What payment methods are accepted for SMAJ51CAHM3/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51CAHM3/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51CAHM3/H?
SMAJ51CAHM3/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51CAHM3/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 SMAJ51CAHM3/H?
For technical support, including SMAJ51CAHM3/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51CAHM3/H requirements.
6.How does Aetrix verify that SMAJ51CAHM3/H is sourced from the original manufacturer or authorized distributors?
All SMAJ51CAHM3/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 SMAJ51CAHM3/H meets industry standards.
7.What is the process for return or replacement of SMAJ51CAHM3/H?
All SMAJ51CAHM3/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51CAHM3/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 SMAJ51CAHM3/H part is unused and in its original packaging.
Return procedure for SMAJ51CAHM3/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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