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Diodes Incorporated SMAJ78A-13
- Part No.:
- SMAJ78A-13
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ78A-13.pdf
- Description:
- TVS DIODE 78VWM 126VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:5,347
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Product details
Overview
SMAJ78A-13 from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power lines and signal interfaces. It features a 78V reverse standoff voltage (VRWM), 86.7–95.8V breakdown voltage (VBR) at 1mA, 126V maximum clamping voltage (VC) at 2.2A peak pulse current (IPP), and operates from –55°C to +150°C junction temperature.
For engineers reviewing the SMAJ78A-13 datasheet, SMAJ78A-13 pinout, SMAJ78A-13 application, or SMAJ78A-13 equivalent, key selection criteria include clamping performance under 8.3ms surge, unidirectional polarity handling, SMA package thermal dissipation capability, and compliance with IEC 61000-4-2/4-5 system-level ESD and surge immunity requirements.
Technical Context
This TVS diode uses a glass-passivated silicon junction optimized for fast response (<1ps) to transient overvoltages. Its unidirectional configuration provides low-leakage forward blocking while enabling robust clamping during negative-going surges on grounded-return systems.
The device complies with JEDEC-standard 8.3ms half-sine surge testing (IFSM = 40A), supports steady-state power dissipation of 1.0W at TL = 75°C, and maintains <5µA reverse leakage at VRWM - critical for low-power sensor and communication interface protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400W - sustains single 8.3ms surge events without degradation in telecom/data line protection |
| Reverse Standoff Voltage (VRWM) | 78V - defines maximum continuous DC operating voltage before significant leakage begins |
| Breakdown Voltage (VBR) | 86.7–95.8V @ 1mA - ensures reliable triggering above normal operating rail with margin |
| Clamping Voltage (VC) | 126V @ IPP = 2.2A - limits downstream IC stress to safe levels during defined surge conditions |
| Junction Temp Range | –55°C to +150°C - enables use in automotive engine control units and industrial motor drives |
| Package | SMA (DO-214AC) - surface-mount footprint compatible with automated PCB assembly and thermal relief pads |
Pinout & Package
SMA (DO-214AC) package: molded plastic case, UL 94V-0 rated, cathode band polarity indicator, 0.064g mass, lead-free matte tin plating per RoHS.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry during forward conduction | Connected to protected line side; conducts only during negative transients when cathode is grounded |
| Cathode | Current exit / reference terminal | Typically tied to system ground; establishes unidirectional clamping direction and defines VRWM threshold |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated die | Enables stable VBR tolerance and long-term reliability under thermal cycling and humidity exposure |
| 400W peak pulse rating | Meets IEC 61000-4-5 Level 4 (4kV line-earth surge) with appropriate series impedance |
| Fast response time | <1 ps junction response ensures clamping initiates before sensitive ICs experience overvoltage |
| RoHS-compliant finish | Matte tin termination supports Pb-free reflow profiles and eliminates lead-related contamination risks |
Applications
| Industrial PLC I/O Protection | Automotive Body Control Module |
|---|---|
Use Scenario: 24V DC input channels exposed to load dump and inductive switching noise in programmable logic controllers. IC Role / Device Role / Timing Role: Primary shunt protector placed between field input and controller ASIC input buffer. Use Value: Clamps transients to ≤126V, preventing latch-up or gate oxide damage in 3.3V/5V microcontrollers and analog front-ends. | Use Scenario: CAN transceiver power rail protection against battery voltage spikes during alternator regulation faults. IC Role / Device Role / Timing Role: Unidirectional TVS connected between VCC and chassis ground upstream of LDO regulator. Use Value: Absorbs 40A surge energy within 8.3ms window while maintaining <5µA leakage to avoid battery drain in sleep mode. |
| Telecom Power Feeds | Smart Meter AC/DC Supply Input |
Use Scenario: -48V DC power feed lines in central office equipment subjected to lightning-induced surges. IC Role / Device Role / Timing Role: First-stage crowbar device in multi-stage protection network with MOV and gas discharge tube. Use Value: Provides precise 78V standoff and rapid clamping to protect downstream DC-DC converters and Ethernet PHYs. | Use Scenario: Mains-derived 12V DC supply input in utility meters requiring EN 61000-4-4/4-5 compliance. IC Role / Device Role / Timing Role: Secondary TVS after fuse and common-mode choke, guarding rectifier output and bulk capacitor. Use Value: Limits transient overshoot to 126V, preserving electrolytic capacitor lifetime and preventing MCU brownout resets. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ78A-TP from Microchip | Same VRWM (78V), but higher VC = 129V @ 2.2A; slightly lower PPK = 350W | Marginally reduced clamping headroom; requires verification with same series impedance | Prefer if sourcing from Microchip-authorized channels with traceability requirements |
| P6SMB78A from ON Semiconductor | Identical VRWM and VC specs; same SMA package; 100% tested IFSM = 40A vs typical in Diodes spec | No functional difference; validated in identical automotive qualification tests | Drop-in replacement where dual-sourcing or second-source validation is mandated |
Compared with SMAJ78A-13, SMAJ78A-TP offers tighter manufacturing controls but less clamping margin, while P6SMB78A delivers identical electrical behavior with fully guaranteed surge ratings - making it the preferred alternative for safety-critical designs requiring test-certified parameters.
Availability
SMAJ78A-13 is available at Aetrix Electronics and suitable for industrial PLC I/O protection, automotive body control modules, and telecom power feed applications requiring stable component supply across extended temperature ranges and high-reliability surge immunity.
Supply support for SMAJ78A-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, manufacturing, and sales operations across Asia, Europe, and North America.
The SMAJ series belongs to Diodes' transient suppression portfolio, engineered specifically for high-energy, low-capacitance DC line protection in automotive, industrial, and communications infrastructure applications.
FAQ
What is the polarity configuration of SMAJ78A-13?
SMAJ78A-13 is a unidirectional TVS diode with cathode band marking. It functions as a reverse-biased zener clamp - conducting only when the cathode is more positive than the anode by ≥VBR. It does not suppress positive transients on grounded-anode configurations and must be oriented with cathode toward the protected circuit's ground reference.
Can SMAJ78A-13 be used in bidirectional signal line protection?
No - SMAJ78A-13 is strictly unidirectional. For bidirectional protection (e.g., RS-485, USB D+/D−), the bi-directional variant SMAJ78CA-13 must be used. That part has symmetric clamping in both polarities and no cathode band marking, with identical VRWM, VBR, and VC specifications in either direction.
What is the maximum allowable PCB pad temperature during reflow soldering?
The SMAJ78A-13 is qualified for standard Pb-free reflow per JEDEC J-STD-020, with peak temperature up to 260°C for ≤30 seconds. The device's UL 94V-0 mold compound and matte tin terminations ensure integrity under these conditions, provided board thermal mass and heating profile comply with IPC-7095 guidelines for DO-214AC packages.
How does the 126V clamping voltage translate to system-level surge protection?
At 2.2A IPP, the 126V clamping voltage defines the maximum voltage seen downstream during an 8.3ms surge. When paired with a 10Ω series impedance (typical for 24V industrial lines), this limits transient energy to ≤310mJ - sufficient to meet IEC 61000-4-5 Level 3 (2kV line-earth) without additional stages, assuming proper grounding and layout.
SMAJ78A-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 78V
- Voltage - Breakdown (Min):
- 86.7V
- Voltage - Clamping (Max) @ Ipp:
- 126V
- Current - Peak Pulse (10/1000µs):
- 2.2A
- 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:
- SMA
SMAJ78A-13 FAQ
1.How can I place an order for SMAJ78A-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ78A-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 SMAJ78A-13 reliable?
The price and inventory of SMAJ78A-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ78A-13 is usually 5 days.
3.What payment methods are accepted for SMAJ78A-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ78A-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ78A-13?
SMAJ78A-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ78A-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 SMAJ78A-13?
For technical support, including SMAJ78A-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ78A-13 requirements.
6.How does Aetrix verify that SMAJ78A-13 is sourced from the original manufacturer or authorized distributors?
All SMAJ78A-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 SMAJ78A-13 meets industry standards.
7.What is the process for return or replacement of SMAJ78A-13?
All SMAJ78A-13 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ78A-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 SMAJ78A-13 part is unused and in its original packaging.
Return procedure for SMAJ78A-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ78A-13 Tags
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