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Vishay General Semiconductor - Diodes Division SMAJ78CA-M3/5A
- Part No.:
- SMAJ78CA-M3/5A
- Manufacturer:
- Vishay General Semiconductor - Diodes Division
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CA-M3/5A.pdf
- Description:
- TVS DIODE 78VWM 126VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:3,944
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Product details
Overview
SMAJ78CA-M3/5A 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 power and signal lines. It features a 78 V standoff voltage (VWM), 86.7–95.8 V breakdown voltage (VBR) at 1 mA, 126 V maximum clamping voltage (VC) at 3.2 A peak pulse current (IPPM), and 300 W peak pulse power rating (10/1000 μs waveform) - optimized for automotive and industrial power rail protection.
For engineers reviewing the SMAJ78CA-M3/5A datasheet, SMAJ78CA-M3/5A pinout, SMAJ78CA-M3/5A application, or SMAJ78CA-M3/5A equivalent, key selection criteria include bidirectional clamping capability, low clamping ratio (VC/VWM ≈ 1.61), MSL Level 1 moisture sensitivity, halogen-free RoHS compliance (M3 suffix), and AEC-Q101 qualification readiness via HM3 variant.
Technical Context
This TVS diode operates symmetrically in both directions due to its CA (bidirectional) configuration, with no polarity marking on the device body. Its glass-passivated junction enables fast response time (<1 ns) and low incremental surge resistance, critical for suppressing ESD and inductive switching spikes before sensitive downstream circuitry is damaged.
The device is rated for -55 °C to +150 °C operating junction temperature, with thermal resistance of 120 °C/W (junction-to-ambient) and 30 °C/W (junction-to-lead). Derating applies above 25 °C ambient per Figure 2; at 78 V VWM, peak pulse power drops from 300 W to ~240 W at TA = 85 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 78 V - maximum continuous reverse working voltage before clamping begins; defines safe operating margin for 72–80 V nominal DC rails |
| VBR min/max | 86.7 V / 95.8 V at IT = 1 mA - tight breakdown tolerance ensures predictable turn-on across production lots |
| VC @ IPPM | 126 V at 3.2 A - clamping voltage limits transient overvoltage seen by protected ICs or MOSFETs |
| PPPM | 300 W (10/1000 μs) - peak surge energy handling capacity for repetitive transients in automotive load-dump scenarios |
| ID @ VWM | 1.0 μA - ultra-low leakage preserves battery life and avoids false triggering in high-impedance sensor interfaces |
| TJ max | +150 °C - supports under-hood automotive placement and industrial environments with elevated ambient temperatures |
| Package | SMA (DO-214AC) - industry-standard surface-mount outline compatible with automated pick-and-place and reflow soldering |
Pinout & Package
Package: SMA (DO-214AC), molded plastic case with matte tin-plated leads, UL 94 V-0 rated, MSL Level 1 (260 °C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Terminal 1 (cathode-band side) | For bidirectional operation, this terminal connects to either side of protected line; no functional polarity distinction |
| Cathode | Terminal 2 (opposite cathode-band side) | Identical to Anode in CA devices; terminals are symmetrical and interchangeable in circuit layout |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating signal lines without polarity concerns |
| 300 W peak pulse power | Withstands automotive ISO 7637-2 Pulse 5a (load dump) surges up to 126 V on 12 V systems |
| MSL Level 1 rating | Allows unlimited floor life and standard reflow profile use without baking preconditioning |
| Halogen-free & RoHS-compliant (M3) | Meets environmental compliance requirements for global automotive and industrial OEM programs |
| Low clamping ratio (VC/VWM = 1.61) | Minimizes overvoltage stress on protected components compared to higher-ratio alternatives |
Applications
| Automotive Power Rail Protection | Industrial Sensor Interface Protection |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs against load dump transients per ISO 7637-2. IC Role / Device Role / Timing Role: Primary clamping element placed upstream of DC-DC converters and microcontrollers. Use Value: Limits transient voltage to ≤126 V, preventing latch-up or gate oxide damage in downstream 16 V-rated ICs. |
Use Scenario: Shielding analog sensor outputs (e.g., pressure, temperature) from ESD and cable discharge events. IC Role / Device Role / Timing Role: Low-capacitance shunt protector on differential or single-ended signal traces. Use Value: Sub-μA leakage avoids signal offset errors; <1 ns response captures fast ESD pulses before op-amp input stages saturate. |
| Telecom Line Interface Protection | Consumer Power Adapter Input Stage |
Use Scenario: Safeguarding PoE-powered Ethernet PHYs and data line transceivers from lightning-induced surges. IC Role / Device Role / Timing Role: Secondary-level TVS on secondary-side DC lines after primary surge arrestors. Use Value: Bidirectional symmetry matches AC-coupled Ethernet signaling; 126 V VC aligns with 100BASE-TX common-mode voltage limits. |
Use Scenario: Clamping inrush and line-switching transients on AC/DC adapter DC output rails feeding USB-C PD controllers. IC Role / Device Role / Timing Role: Final-stage transient suppressor before voltage regulation and USB interface ICs. Use Value: 78 V VWM accommodates 5 V–20 V wide-input adapters; 300 W rating handles repeated plug/unplug surges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-M3/5A | Unidirectional; 86.7–95.8 V VBR, same VC/PPPM, but marked cathode band and asymmetric conduction | Requires correct polarity placement; unsuitable for AC or floating lines | Select only when protecting DC rails with known polarity and space-constrained layouts needing unidirectional optimization |
| SMBJ78CA-M3/5A | Same VWM/VBR/VC specs but in SMB (DO-214AA) package - 27% larger footprint, 600 W PPPM rating | Higher surge margin for infrequent high-energy events; less suitable for dense PCBs | Choose when system-level testing requires >300 W headroom or legacy SMB footprints must be retained |
Compared with SMAJ78CA-M3/5A, the unidirectional SMAJ78A-M3/5A demands strict polarity alignment but offers identical clamping performance, while SMBJ78CA-M3/5A trades board area for doubled pulse power - making SMAJ78CA-M3/5A optimal for cost- and space-sensitive bidirectional protection where 300 W suffices.
Availability
SMAJ78CA-M3/5A is available at Aetrix Electronics and suitable for automotive ECU designs, industrial sensor modules, telecom line cards, and consumer power adapter applications requiring stable component supply, halogen-free compliance, and AEC-Q101 qualification path support.
Supply support for SMAJ78CA-M3/5A 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 targets board-level transient suppression in harsh environments, with design focus on fast response, repeatable clamping, and robust packaging for automotive, industrial, and telecom applications.
FAQ
What does the "CA" suffix indicate in SMAJ78CA-M3/5A?
The "CA" suffix denotes bidirectional functionality: SMAJ78CA-M3/5A conducts identically in both directions, with no polarity marking required. This distinguishes it from unidirectional variants like SMAJ78A-M3/5A, which feature a cathode band and conduct only from anode to cathode. The CA configuration simplifies layout for AC-coupled or floating circuits.
Is SMAJ78CA-M3/5A qualified to AEC-Q101?
SMAJ78CA-M3/5A itself is not AEC-Q101 qualified, but Vishay offers the HM3 variant (e.g., SMAJ78CAHM3_A/I) with full AEC-Q101 qualification. The M3 suffix indicates halogen-free RoHS compliance; AEC-Q101 requires additional test documentation and traceability - available under the HM3 ordering code with "_X" revision suffix.
What is the clamping voltage of SMAJ78CA-M3/5A at its rated peak pulse current?
SMAJ78CA-M3/5A has a maximum clamping voltage (VC) of 126 V at 3.2 A peak pulse current (IPPM), measured with a 10/1000 μs waveform. This value is guaranteed across temperature and production lot, ensuring consistent overvoltage limiting for protected downstream components such as microcontrollers or power MOSFETs.
Can SMAJ78CA-M3/5A replace SMAJ78A-M3/5A in an existing design?
No direct replacement is possible without layout review: SMAJ78CA-M3/5A is bidirectional with no polarity marking, while SMAJ78A-M3/5A is unidirectional and requires correct cathode orientation. Swapping may cause improper clamping if the original design relies on directional conduction - verify circuit topology and transient directionality before substitution.
What is the thermal resistance of SMAJ78CA-M3/5A, and how does it affect power derating?
SMAJ78CA-M3/5A has a typical junction-to-ambient thermal resistance (RθJA) of 120 °C/W and junction-to-lead (RθJL) of 30 °C/W. At ambient temperatures above 25 °C, peak pulse power must be derated per Figure 2 in the datasheet - e.g., at 85 °C TA, PPPM drops to ~240 W, directly impacting surge survivability in high-temperature enclosures.
SMAJ78CA-M3/5A 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-M3/5A FAQ
1.How can I place an order for SMAJ78CA-M3/5A through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CA-M3/5A 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-M3/5A reliable?
The price and inventory of SMAJ78CA-M3/5A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CA-M3/5A is usually 5 days.
3.What payment methods are accepted for SMAJ78CA-M3/5A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CA-M3/5A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CA-M3/5A?
SMAJ78CA-M3/5A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CA-M3/5A 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-M3/5A?
For technical support, including SMAJ78CA-M3/5A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CA-M3/5A requirements.
6.How does Aetrix verify that SMAJ78CA-M3/5A is sourced from the original manufacturer or authorized distributors?
All SMAJ78CA-M3/5A 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-M3/5A meets industry standards.
7.What is the process for return or replacement of SMAJ78CA-M3/5A?
All SMAJ78CA-M3/5A units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CA-M3/5A, 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-M3/5A part is unused and in its original packaging.
Return procedure for SMAJ78CA-M3/5A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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