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Vishay General Semiconductor - Diodes Division SMAJ78CA-E3/5A
- Part No.:
- SMAJ78CA-E3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CA-E3/5A.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,568
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Product details
Overview
SMAJ78CA-E3/5A from Vishay General Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for clamping voltage transients on signal or power lines. 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 rating (10/1000 μs waveform) - suitable for protecting MOSFET gates, sensor interfaces, and automotive control modules against ESD and inductive switching surges.
For engineers reviewing the SMAJ78CA-E3/5A datasheet, SMAJ78CA-E3/5A pinout, SMAJ78CA-E3/5A application, or SMAJ78CA-E3/5A equivalent, key selection criteria include bidirectional clamping symmetry, low clamping ratio (VC/VWM = 1.61), AEC-Q101 qualification eligibility, thermal resistance (RθJA = 120 °C/W), and compatibility with automated SMT placement on 5.0 mm × 5.0 mm copper pads.
Technical Context
This bidirectional TVS operates symmetrically in both polarities, with identical VBR, VC, and IPPM characteristics in forward and reverse directions. Its glass-passivated junction enables fast response time (<1 ps) and stable surge performance under repetitive 0.01% duty cycle conditions.
The device complies with ANSI/IEEE C62.35 for transient suppressors and meets UL 497B recognition (QVGQ2). It is rated for operation from −55 °C to +150 °C junction temperature, with MSL Level 1 moisture sensitivity and matte tin-plated leads compliant with J-STD-002 and JESD 22-B102.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - Maximum continuous reverse operating voltage before significant leakage; defines safe working margin below clamping threshold |
| VBR (min/max) | 86.7 V / 95.8 V at 1 mA - Confirmed breakdown range ensures reliable turn-on during overvoltage events without premature conduction |
| VC @ IPPM | 126 V at 3.2 A - Clamping voltage limits downstream IC stress during 10/1000 μs transients; clamping ratio = 1.61 |
| PPPM | 400 W (≤78 V), 300 W (>78 V) - Peak pulse power handling capability on standard 0.2" × 0.2" copper pads per terminal |
| ID @ VWM | 1.0 μA - Ultra-low reverse leakage preserves signal integrity and minimizes standby power loss in high-impedance circuits |
| TJ max. | +150 °C - Enables use in under-hood automotive environments and industrial enclosures without derating penalties |
| RθJA | 120 °C/W - Thermal resistance determines required PCB copper area for sustained power dissipation; mandates ≥5 mm² pad per terminal |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, bidirectional configuration with no polarity marking - terminals are symmetrical anode/cathode pair.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current entry (either polarity) | Accepts surge current during positive or negative voltage excursions; connects to protected line |
| Cathode | Transient current exit (either polarity) | Completes low-impedance path to ground or return rail; bidirectional symmetry eliminates orientation dependency |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Identical VBR, VC, and IPPM in both directions - eliminates need for polarity-aware layout or external series components |
| 400 W peak pulse power | Rated at 10/1000 μs waveform on 5.0 mm × 5.0 mm copper pads - supports robust protection against ISO 7637-2 Pulse 1/2a/5a and IEC 61000-4-5 surges |
| Low clamping ratio | VC/VWM = 1.61 - minimizes overvoltage exposure to downstream logic, analog sensors, or gate drivers during clamping |
| AEC-Q101 qualification option | Available as HE3/HM3 variants - enables direct use in automotive powertrain, body electronics, and ADAS modules requiring qualified components |
| MSL Level 1 | Reflow-compatible up to 260 °C peak - supports standard lead-free reflow profiles without baking or special handling |
Applications
| Automotive Sensor Protection | Industrial PLC I/O Protection |
|---|---|
|
Use Scenario: Protecting CAN/LIN bus transceivers and analog sensor inputs (e.g., pressure, temperature) from load dump and inductive kickback in 12 V/24 V vehicle systems. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed across differential signal pairs or supply rails to limit transient excursions to <126 V. Use Value: Prevents latch-up or permanent damage to 3.3 V/5 V interface ICs while maintaining signal fidelity due to sub-1 μA leakage at 78 V. |
Use Scenario: Safeguarding digital input modules in programmable logic controllers exposed to relay coil flyback and motor drive noise in factory automation. IC Role / Device Role / Timing Role: Parallel-connected TVS on 24 V DC input lines to shunt surge energy before it reaches optocoupler or microcontroller GPIO. Use Value: Withstands repeated 400 W pulses at 0.01% duty cycle, enabling long-term reliability in high-noise industrial environments without degradation. |
| Consumer Power Adapter Output | Telecom Line Interface |
|
Use Scenario: Secondary-side overvoltage suppression on AC/DC adapter outputs feeding USB-C PD or multi-rail embedded systems. IC Role / Device Role / Timing Role: Standoff-clamp device between VOUT and GND to absorb output capacitor discharge spikes and regulator fault transients. Use Value: 78 V VWM aligns with 60 V+ output designs; 126 V VC ensures downstream 80 V-rated capacitors remain within safe operating area. |
Use Scenario: Primary protection on Ethernet PHY or RS-485 transceiver lines subjected to lightning-induced surges and ESD per IEC 61000-4-2/4-5. IC Role / Device Role / Timing Role: First-stage TVS on differential data lines to reduce surge amplitude before secondary protection (e.g., GDT + MOV). Use Value: Fast <1 ps response and symmetric clamping preserve signal integrity on high-speed lines while limiting common-mode voltage to ≤126 V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-E3/5A | Unidirectional variant; cathode band marked; VF = 3.5 V at 25 A (forward conduction only) | Requires polarity-aware PCB layout; unsuitable for AC-coupled or floating differential lines | Select when protecting DC-biased single-ended signals where reverse conduction must be blocked |
| SMBJ78CA-T | Same VWM/VC specs but in SMB (DO-214AA) package; 600 W PPPM; RθJA = 80 °C/W | Higher power handling and better thermal performance, but 30% larger footprint | Choose when system-level surge requirements exceed 400 W or board space allows larger package for improved margin |
Compared with SMAJ78CA-E3/5A, the unidirectional SMAJ78A-E3/5A adds polarity constraint but enables DC blocking, while the SMBJ78CA-T offers higher surge capacity and lower thermal resistance at the cost of increased board area - making SMAJ78CA-E3/5A optimal for space-constrained bidirectional protection where 400 W suffices.
Availability
SMAJ78CA-E3/5A is available at Aetrix Electronics and suitable for automotive sensor interfaces, industrial PLC I/O modules, consumer power adapter outputs, and telecom line interfaces requiring stable component supply and RoHS-compliant sourcing.
Supply support for SMAJ78CA-E3/5A 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, automotive qualification, and high-volume manufacturability.
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 readiness are critical design requirements.
FAQ
What does the "CA" suffix indicate in SMAJ78CA-E3/5A?
The "CA" suffix denotes a bidirectional configuration: SMAJ78CA-E3/5A provides symmetrical transient suppression in both polarities, with identical breakdown and clamping characteristics regardless of voltage polarity. This eliminates the need for orientation-specific placement and makes it ideal for AC-coupled lines, differential buses, or floating grounds where polarity reversal may occur during surge events. Unlike unidirectional variants (e.g., SMAJ78A), SMAJ78CA-E3/5A has no cathode band marking.
Is SMAJ78CA-E3/5A AEC-Q101 qualified?
SMAJ78CA-E3/5A itself is the commercial-grade RoHS-compliant version (E3 suffix); however, Vishay offers AEC-Q101-qualified equivalents under ordering codes SMAJ78CAHE3_X (RoHS + AEC-Q101) or SMAJ78CAHM3_X (halogen-free + RoHS + AEC-Q101), where "_X" denotes revision code (e.g., A, B). The base SMAJ78CA-E3/5A meets all electrical and mechanical specs of the qualified versions except formal qualification testing - making it suitable for non-automotive applications or pre-qualification prototyping.
What is the maximum clamping voltage of SMAJ78CA-E3/5A and how is it measured?
The maximum clamping voltage (VC) of SMAJ78CA-E3/5A is 126 V, measured at a peak pulse current (IPPM) of 3.2 A using a standardized 10/1000 μs double-exponential waveform per IEC 61000-4-5. This value represents the upper limit of voltage seen by downstream circuitry during worst-case surge events and is guaranteed across temperature (−55 °C to +150 °C) and lifetime. It reflects actual device behavior under real-world surge stress, not theoretical modeling.
Can SMAJ78CA-E3/5A be used in place of SMAJ78A-E3/5A?
No - SMAJ78CA-E3/5A and SMAJ78A-E3/5A are not interchangeable without layout review. SMAJ78A-E3/5A is unidirectional (cathode-marked) and conducts only in reverse bias, whereas SMAJ78CA-E3/5A is bidirectional and clamps in both directions. Substituting SMAJ78CA-E3/5A for SMAJ78A-E3/5A may cause unintended conduction in forward-biased DC paths. Layout must accommodate symmetric terminal routing and absence of polarity markings when using SMAJ78CA-E3/5A.
What PCB pad layout is recommended for optimal thermal and surge performance of SMAJ78CA-E3/5A?
Vishay specifies a minimum 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pad for each terminal of SMAJ78CA-E3/5A to achieve rated 400 W peak pulse power and thermal resistance (RθJA = 120 °C/W). These pads must be directly connected to internal ground/power planes via multiple thermal vias (≥4 per pad, 0.3 mm diameter) to minimize junction temperature rise during repetitive surges. Reduced pad area de-rates both power handling and clamping stability - confirmed in Figure 2 of datasheet 88390.
SMAJ78CA-E3/5A 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:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ78CA-E3/5A FAQ
1.How can I place an order for SMAJ78CA-E3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CA-E3/5A 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 SMAJ78CA-E3/5A reliable?
The price and inventory of SMAJ78CA-E3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CA-E3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ78CA-E3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CA-E3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CA-E3/5A?
SMAJ78CA-E3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CA-E3/5A 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 SMAJ78CA-E3/5A?
For technical support, including SMAJ78CA-E3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CA-E3/5A requirements.
6.How does Aetrix verify that SMAJ78CA-E3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ78CA-E3/5A 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 SMAJ78CA-E3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ78CA-E3/5A?
All SMAJ78CA-E3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CA-E3/5A, 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 SMAJ78CA-E3/5A part is unused and in its original packaging.
Return procedure for SMAJ78CA-E3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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