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Vishay General Semiconductor - Diodes Division SMAJ78CAHM3_A/H
- Part No.:
- SMAJ78CAHM3_A/H
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CAHM3_A/H.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,569
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Product details
Overview
SMAJ78CAHM3_A/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 78 V standoff voltage (VWM), 86.7–95.8 V breakdown range (VBR at 1 mA), 126 V maximum clamping voltage (VC) at 3.2 A peak pulse current, and 400 W peak pulse power (10/1000 μs waveform) - rated for automotive-grade surge immunity per AEC-Q101.
For engineers reviewing the SMAJ78CAHM3_A/H datasheet, SMAJ78CAHM3_A/H pinout, SMAJ78CAHM3_A/H application, or SMAJ78CAHM3_A/H equivalent, this device is selected for high-reliability DC bus, sensor interface, and power rail protection where fast response (<1 ns), low clamping ratio (1.62×VWM), and halogen-free RoHS compliance are required.
Technical Context
This bidirectional TVS operates symmetrically across both polarities, with identical electrical characteristics in forward and reverse directions. Its glass-passivated junction ensures stable breakdown behavior and low leakage (<1.0 μA at VWM), while the SMA package supports automated SMT placement and meets MSL Level 1 (260 °C reflow peak).
The device delivers 400 W peak pulse power up to 78 V, derating to 300 W above 78 V per Vishay's specification. Thermal resistance is 120 °C/W (junction-to-ambient) on standard 5.0 mm × 5.0 mm copper pads, enabling reliable operation up to +150 °C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse operating voltage before clamping begins |
| VBR (min/max) | 86.7 V / 95.8 V at 1 mA - guaranteed breakdown threshold defining turn-on precision |
| VC @ IPPM | 126 V at 3.2 A - clamped voltage during 10/1000 μs surge, limiting downstream stress |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - surge energy handling capacity under standardized waveform |
| IFSM | 40 A - single half-sine surge rating (8.3 ms), relevant for unidirectional variants only (not applicable here) |
| TJ max | +150 °C - maximum junction temperature enabling use in under-hood automotive environments |
| Package | SMA (DO-214AC) - surface-mount, low-profile package with matte tin-plated leads, J-STD-002 solderable |
Pinout & Package
Package: SMA (DO-214AC), bidirectional configuration - no polarity marking; symmetrical two-terminal construction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Terminal 1 | Anode / Cathode (bidirectional) | Either terminal serves as anode or cathode depending on transient polarity - no fixed polarity |
| Terminal 2 | Anode / Cathode (bidirectional) | Complementary terminal completing symmetrical clamping path; interchangeable with Terminal 1 |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating signal lines without polarity concerns |
| AEC-Q101 qualified | Validated for automotive applications including engine control units and ADAS sensor interfaces |
| Halogen-free & RoHS-compliant | Meets environmental compliance requirements for industrial and consumer end equipment |
| 400 W peak pulse power | Withstands IEC 61000-4-5 Level 4 surges (4 kV line-earth, 2 kV line-line) on properly laid out PCBs |
| MSL Level 1 | Allows unlimited floor life and single-reflow processing at 260 °C peak, simplifying manufacturing |
Applications
| Automotive Sensor Interface | Industrial CAN Bus Protection |
|---|---|
|
Use Scenario: Protecting analog output pins of pressure/temperature sensors in engine bay environments exposed to load dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Bidirectional TVS placed between sensor output and microcontroller ADC input to clamp transients before signal conditioning circuitry. Use Value: Clamps 126 V surges at 3.2 A while maintaining <1.0 μA leakage at 78 V, preserving signal integrity and preventing ADC saturation. |
Use Scenario: Safeguarding CANH/CANL differential pair against ESD and inductive switching noise in factory automation controllers. IC Role / Device Role / Timing Role: Two SMAJ78CAHM3_A/H devices deployed in common-mode configuration across CANH-GND and CANL-GND. Use Value: Symmetric 86.7–95.8 V breakdown ensures balanced clamping on both lines, preserving differential signaling integrity during 400 W surges. |
| DC Power Rail Protection | Telecom Line Card Surge Suppression |
|
Use Scenario: Guarding 72–80 V DC distribution rails in telecom remote radio units against lightning-induced surges. IC Role / Device Role / Timing Role: Primary TVS placed upstream of DC-DC converters and PMICs to limit rail voltage excursions. Use Value: 126 V clamping voltage provides ≥20 V margin above nominal 78 V rail, allowing downstream regulators to remain functional during transient events. |
Use Scenario: Protecting Ethernet PHY interface power supplies (e.g., 75 V bias rails) in outdoor base station line cards. IC Role / Device Role / Timing Role: Bidirectional suppression on isolated auxiliary supply lines susceptible to induced surges from nearby RF amplifiers. Use Value: Halogen-free SMA package enables compliance with IPC-1752A reporting requirements while delivering 300–400 W surge capability per line. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78CAHE3_A/H | Same electrical specs; RoHS-compliant but not halogen-free; uses standard tin plating instead of matte tin | Lacks halogen-free certification; suitable for commercial-grade non-automotive designs | Select when halogen-free requirement is absent and cost sensitivity outweighs environmental compliance needs |
| SMAJ78A-HM3_A/H | Unidirectional variant; includes cathode band marking; same VWM, VBR, VC, PPPM | Requires polarity-aware layout; used where DC-biased lines need asymmetric protection | Choose only if circuit topology enforces unidirectional bias and polarity can be reliably maintained |
Compared with SMAJ78CAHE3_A/H and SMAJ78A-HM3_A/H, the SMAJ78CAHM3_A/H uniquely combines bidirectional symmetry, halogen-free construction, and AEC-Q101 qualification - making it the sole option for automotive-grade, polarity-agnostic, environmentally compliant surge protection in 78 V systems.
Availability
SMAJ78CAHM3_A/H is available at Aetrix Electronics and suitable for automotive sensor modules, industrial CAN networks, and telecom DC power systems requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for SMAJ78CAHM3_A/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, MOSFETs, optoelectronics, and passive components with emphasis on reliability and application-specific performance.
The SMAJ series targets high-energy transient suppression in harsh environments, with design focus on automotive, industrial, and telecom infrastructure where AEC-Q101 validation and precise clamping are critical.
FAQ
What does the "CA" suffix indicate in SMAJ78CAHM3_A/H?
The "CA" suffix denotes a bidirectional configuration - meaning SMAJ78CAHM3_A/H provides symmetrical transient suppression in both polarities, unlike unidirectional "A" variants that require correct cathode orientation. This eliminates polarity dependency during board assembly and enables protection of AC-coupled or floating nodes without redesign.
Is SMAJ78CAHM3_A/H qualified for automotive applications?
Yes, SMAJ78CAHM3_A/H is AEC-Q101 qualified, as confirmed by Vishay's ordering code structure ("HM3" suffix indicates halogen-free + AEC-Q101). It is validated for use in engine control, body electronics, and ADAS sensor modules where sustained operation at +150 °C and immunity to repetitive load-dump transients are required.
How does the clamping voltage of SMAJ78CAHM3_A/H compare to its standoff voltage?
SMAJ78CAHM3_A/H has a 78 V standoff voltage (VWM) and clamps at 126 V (VC) under 3.2 A surge current, yielding a clamping ratio of 1.62. This ratio reflects real-world overvoltage margin - ensuring protected ICs see no more than 126 V during standardized 10/1000 μs transients, well within safe operating limits for 100 V-rated components.
What is the thermal resistance of SMAJ78CAHM3_A/H, and how does it affect layout?
SMAJ78CAHM3_A/H has a typical RθJA of 120 °C/W when mounted on 5.0 mm × 5.0 mm copper pads per terminal. To maintain TJ ≤ 150 °C under 400 W surge conditions, designers must ensure adequate copper area and avoid excessive ambient temperature buildup - especially in enclosed automotive enclosures.
Does SMAJ78CAHM3_A/H have a polarity marking on the package?
No, SMAJ78CAHM3_A/H has no polarity marking because it is a bidirectional device - both terminals are functionally identical. Unlike unidirectional SMAJ78A-HM3_A/H (which features a cathode band), SMAJ78CAHM3_A/H relies on symmetrical internal structure, eliminating orientation constraints during pick-and-place assembly.
SMAJ78CAHM3_A/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:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- 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)
SMAJ78CAHM3_A/H FAQ
1.How can I place an order for SMAJ78CAHM3_A/H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CAHM3_A/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 SMAJ78CAHM3_A/H reliable?
The price and inventory of SMAJ78CAHM3_A/H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CAHM3_A/H is usually 5 days.
3.What payment methods are accepted for SMAJ78CAHM3_A/H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CAHM3_A/H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CAHM3_A/H?
SMAJ78CAHM3_A/H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CAHM3_A/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 SMAJ78CAHM3_A/H?
For technical support, including SMAJ78CAHM3_A/H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CAHM3_A/H requirements.
6.How does Aetrix verify that SMAJ78CAHM3_A/H is sourced from the original manufacturer or authorized distributors?
All SMAJ78CAHM3_A/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 SMAJ78CAHM3_A/H meets industry standards.
7.What is the process for return or replacement of SMAJ78CAHM3_A/H?
All SMAJ78CAHM3_A/H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CAHM3_A/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 SMAJ78CAHM3_A/H part is unused and in its original packaging.
Return procedure for SMAJ78CAHM3_A/H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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