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Diodes Incorporated SMAJ78CA-13
- Part No.:
- SMAJ78CA-13
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78CA-13.pdf
- Description:
- TVS DIODE 78VWM 126VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:2,496
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Product details
Overview
SMAJ78CA-13 from Diodes Incorporated is a 400W bi-directional transient voltage suppressor (TVS) diode in SMA package, designed for clamping ESD and surge transients on data lines and power rails. It features a 78V reverse standoff voltage (VRWM), 86.7–95.8V breakdown range (VBR @ IT = 1mA), 126V max clamping voltage at 2.2A peak pulse current (IPP), and operates from –55°C to +150°C - used in industrial Ethernet port protection and automotive body control module I/O interfaces.
For engineers reviewing the SMAJ78CA-13 datasheet, SMAJ78CA-13 pinout, SMAJ78CA-13 application, or SMAJ78CA-13 equivalent, key selection criteria include clamping voltage margin vs. system rail, unidirectional/bi-directional polarity requirement, peak pulse current handling under 8.3ms half-sine stress, and RoHS-compliant lead-free plating compatibility with reflow profiles.
Technical Context
This bi-directional TVS diode uses glass-passivated junction construction for stable breakdown characteristics and fast response (<1 ps). It clamps both positive and negative transients symmetrically without polarity dependence, making it suitable for AC-coupled or floating signal paths where bidirectional surge immunity is required.
Its 400W peak pulse power rating is specified under non-repetitive 8.3ms half-sine waveform conditions (JEDEC method), with derating above 25°C ambient per Fig. 1. Steady-state power dissipation is limited to 1.0W at lead temperature TL = 75°C, and maximum forward voltage is not rated - confirming its intended use as a clamping-only device, not for DC conduction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400W - sustains single 8.3ms surge events without failure; requires thermal management for repeated surges. |
| Reverse Standoff Voltage (VRWM) | 78V - maximum continuous working voltage before significant leakage; sets upper limit for protected circuit rail. |
| Breakdown Voltage (VBR) | 86.7–95.8V @ 1mA - defines onset of avalanche conduction; tight tolerance ensures predictable clamping threshold. |
| Max Clamping Voltage (VC) | 126V @ IPP = 2.2A - actual voltage seen by downstream circuit during worst-case surge; determines system overvoltage margin. |
| Peak Pulse Current (IPP) | 2.2A - maximum transient current the device can shunt while maintaining VC ≤ 126V; correlates directly to IEC 61000-4-5 Level 3 immunity. |
| Operating Temperature | –55°C to +150°C - supports under-hood automotive and industrial control environments without derating. |
| RoHS Compliance | Lead-free matte tin finish - compatible with standard Pb-free reflow profiles and meets EU Directive Annex exemptions. |
Pinout & Package
Package: SMA (DO-214AC), surface-mount, molded plastic case with UL 94V-0 flammability rating. Cathode band omitted (bi-directional device).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Bi-directional avalanche terminals | No polarity - either terminal accepts positive or negative transient; connected across protected line and ground (or between differential lines). |
| Case | Non-electrical mechanical interface | Plastic body provides insulation and mechanical anchoring; no thermal or electrical connection to PCB copper pour required. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated die | Ensures stable VBR over lifetime and temperature; eliminates parameter drift due to moisture or contamination. |
| 400W peak pulse rating | Provides robust immunity against IEC 61000-4-5 4kV/2Ω combination wave surges on 24V/48V industrial buses. |
| Bi-directional configuration | Enables single-device protection of AC signals (e.g., RS-485, CAN FD differential pairs) without external polarity logic. |
| Fast response time | <1 ps junction response - clamps transients before sensitive ICs experience overstress, critical for high-speed interface protection. |
| UL 94V-0 flammability rating | Prevents flame propagation during catastrophic surge failure, meeting safety requirements for industrial enclosures. |
Applications
| Industrial Ethernet Port Protection | Automotive Body Control Module I/O |
|---|---|
Use Scenario: Protecting RJ45 PHY interface pins against ESD (IEC 61000-4-2 ±8kV contact) and lightning-induced surges (IEC 61000-4-5). IC Role / Device Role: Bi-directional clamping element placed between differential pair (TX+/TX−) and chassis ground. Use Value: Limits transient voltage to ≤126V, preserving PHY IC integrity while maintaining signal integrity up to 100 Mbps. | Use Scenario: Safeguarding LIN bus or sensor inputs (e.g., door latch, mirror position) from load dump and jump-start transients. IC Role / Device Role: Line-to-ground TVS on 12V supply input or signal return path in BCU subassembly. Use Value: Withstands 2.2A surge current at 126V clamping, preventing latch-up or gate oxide damage in microcontroller GPIOs. |
| 48V Telecom Power Rail Protection | Programmable Logic Controller (PLC) Digital Input |
Use Scenario: Guarding primary-side 48V DC-DC converter inputs against ISO 7637-2 Pulse 1/2a/5a transients in telecom infrastructure. IC Role / Device Role: Bidirectional shunt device across 48V rail and return, upstream of bulk capacitor. Use Value: Clamps 78V nominal rail to 126V during 2.2A surge, avoiding overvoltage shutdown of downstream PMICs. | Use Scenario: Protecting 24V digital input channels in modular PLC backplanes from field-wiring induced surges and ESD. IC Role / Device Role: Line-to-ground TVS on each isolated input channel, mounted adjacent to optocoupler input. Use Value: Enables compliance with IEC 61000-4-4 (EFT) and IEC 61000-4-5 (surge) without adding series impedance or signal delay. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78CA-13 | Same VRWM/VBR/VC specs but SMB package (higher thermal mass, 600W PPK rating) | Better suited for higher-energy surges; larger footprint may conflict with dense PCB layouts | Select when surge energy exceeds 400W capability or board layout allows SMB footprint |
| P6SMB78CA | Identical electrical specs; same SMB package; manufactured by STMicroelectronics | Same thermal and clamping performance; different date code marking and reel packaging standards | Use for dual-sourcing; verify reel taping and traceability documentation alignment with OEM requirements |
Compared with SMAJ78CA-13, SMBJ78CA-13 offers 50% higher surge power headroom at the cost of 40% larger board area, while P6SMB78CA delivers identical protection with alternate supply-chain validation - enabling design flexibility without compromising clamping accuracy or temperature range.
Availability
SMAJ78CA-13 is available at Aetrix Electronics and suitable for industrial Ethernet port protection, automotive body control module I/O, and 48V telecom power rail protection requiring stable component supply across multi-year production cycles.
Supply support for SMAJ78CA-13 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the US.
The SMAJ series belongs to Diodes' transient voltage suppressor product line, engineered specifically for high-reliability surge and ESD protection in harsh industrial, automotive, and communications environments.
FAQ
What is the meaning of the 'C' suffix in SMAJ78CA-13?
The 'C' denotes bi-directional configuration - the device clamps transients of either polarity symmetrically across its terminals. Unlike unidirectional variants (e.g., SMAJ78A-13), it has no cathode band and is used where AC signals or floating references require equal positive/negative surge immunity, such as RS-485 or CAN bus lines.
Can SMAJ78CA-13 be used in place of a unidirectional TVS like SMAJ78A-13?
Yes, but only if polarity independence is acceptable and system grounding permits symmetrical clamping. Replacing a unidirectional TVS with SMAJ78CA-13 introduces no electrical risk, though it removes the ability to exploit forward conduction for DC biasing - a feature sometimes used in legacy crowbar circuits.
What is the maximum allowable PCB pad temperature during reflow soldering?
The SMAJ78CA-13 is qualified for lead-free reflow per JEDEC J-STD-020C, with peak temperature up to 260°C for 30 seconds. Its glass-passivated die and matte tin finish ensure reliability under standard Pb-free profiles; preheat and soak zones must follow Diodes' recommended ramp rates to avoid thermal shock cracking.
How does the 126V clamping voltage relate to system-level surge testing?
The 126V clamping voltage is measured at 2.2A IPP under 8.3ms half-sine waveform - matching IEC 61000-4-5 Level 3 (1kV/2Ω) test conditions. To ensure system pass/fail margin, the protected IC's absolute maximum rating must exceed 126V by ≥20%, and PCB trace inductance must be minimized to prevent overshoot beyond VC.
SMAJ78CA-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 2
- 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:
- Yes
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMAJ)
SMAJ78CA-13 FAQ
1.How can I place an order for SMAJ78CA-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78CA-13 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-13 reliable?
The price and inventory of SMAJ78CA-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78CA-13 is usually 5 days.
3.What payment methods are accepted for SMAJ78CA-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78CA-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78CA-13?
SMAJ78CA-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78CA-13 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-13?
For technical support, including SMAJ78CA-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78CA-13 requirements.
6.How does Aetrix verify that SMAJ78CA-13 is sourced from the original manufacturer or authorized distributors?
All SMAJ78CA-13 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-13 meets industry standards.
7.What is the process for return or replacement of SMAJ78CA-13?
All SMAJ78CA-13 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78CA-13, 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-13 part is unused and in its original packaging.
Return procedure for SMAJ78CA-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ78CA-13 Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
Diodes Incorporated
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onsemi
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D5V0H1B2LP-7B
Diodes Incorporated
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Diodes Incorporated
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DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
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Diodes Incorporated
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Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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