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Diodes Incorporated P4SMAJ78ADF-13
- Part No.:
- P4SMAJ78ADF-13
- Manufacturer:
- Diodes Incorporated
- Category:
- TVS Diodes
- Package:
- 2-SMD, Flat Leads
- Datasheet:
-
P4SMAJ78ADF-13.pdf
- Description:
- TRANSIENT VOLTAGE SUPPRESSOR D-F
- Quantity:
- Payment:
- Shipping:
Inventory:8,772
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Product details
Overview
P4SMAJ78ADF-13 from Diodes Incorporated is a 400W surface-mount transient voltage suppressor (TVS) diode designed for unidirectional overvoltage protection in DC power rails and signal lines. It features a reverse standoff voltage of 78 V, clamping voltage of 126 V at 3.2 A peak pulse current, and IEC 61000-4-2 ESD rating of ±30 kV (air/contact). Used in industrial power supplies and automotive body electronics to safeguard microcontrollers and sensors against lightning-induced surges.
For engineers reviewing the P4SMAJ78ADF-13 datasheet, P4SMAJ78ADF-13 pinout, P4SMAJ78ADF-13 application, or P4SMAJ78ADF-13 equivalent, key selection criteria include clamping voltage margin relative to protected IC VDD, peak pulse current capability under 10/1000 µs waveform, thermal resistance on FR-4 PCB, and D-FLAT package compatibility with high-density layouts.
Technical Context
This unidirectional TVS operates in avalanche breakdown mode during transients, diverting surge current away from downstream circuitry while maintaining low clamping voltage. Its glass-passivated junction ensures stable breakdown characteristics and long-term reliability under repetitive surge stress.
The device complies with IEC 61000-4-2 Level 4 ESD immunity (±30 kV contact/air), supports 40 A non-repetitive forward surge current (8.3 ms half-sine), and exhibits typical junction-to-terminal thermal resistance of 37 °C/W when mounted on a 1"×1" 2 oz copper pad - critical for sustained power dissipation in compact designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400 W - sustains single 10×1000 µs surges without failure; derates linearly above +25°C ambient |
| Reverse Standoff Voltage (VRWM) | 78 V - maximum continuous DC voltage before leakage exceeds 1 µA; sets upper limit for protected rail |
| Clamping Voltage (VC) | 126 V @ IPP = 3.2 A - peak voltage seen by protected circuit during worst-case transient; defines safe operating margin |
| Breakdown Voltage (VBR) | 86.7–95.8 V @ IT = 1 mA - tight tolerance ensures consistent turn-on across production lots |
| Thermal Resistance (RθJT) | 37 °C/W - enables 1.0 W steady-state dissipation at TL = +75°C with proper PCB copper area |
| ESD Rating | ±30 kV air / ±30 kV contact per IEC 61000-4-2 - eliminates need for external ESD diodes in many interfaces |
Pinout & Package
Package: D-FLAT (low-profile surface-mount package with 2.25–2.95 mm width, 3.95–4.60 mm length, 0.90–1.10 mm height; UL 94V-0 molded plastic case; cathode band polarity indicator).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Cathode) | Surge Current Sink | Connected to protected line; conducts avalanche current to ground during overvoltage events |
| 2 (Anode) | Reference Node | Typically tied to system ground; establishes reference for clamping action and defines unidirectional behavior |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated die construction | Ensures stable VBR and low leakage (<1 µA at VRWM) over temperature and lifetime |
| D-FLAT low-profile package | Reduces board space by >40% vs. SMA; compatible with automated SMT placement and reflow |
| IEC 61000-4-2 ±30 kV ESD rating | Meets automotive and industrial immunity standards without supplemental ESD protection |
| Lead-free, halogen-free, RoHS 3 compliant | Fulfills EU environmental directives and supports green manufacturing requirements |
Applications
| Industrial PLC I/O Modules | Automotive Body Control Units |
|---|---|
Use Scenario: Protects 24 V CAN/LIN bus interface circuits from load dump and ISO 7637-2 pulse 1/2a transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between signal line and chassis ground to clamp surges before reaching transceiver input. Use Value: Clamps to 126 V within nanoseconds, keeping transceiver VIO below absolute maximum rating during 100 V/50 ms pulses. |
Use Scenario: Safeguards microcontroller GPIOs and sensor inputs in door module ECUs exposed to battery disconnect spikes. IC Role / Device Role / Timing Role: Primary overvoltage clamp on 5 V/3.3 V supply rails feeding Hall-effect sensors and LED drivers. Use Value: Withstands 40 A 8.3 ms surge current while limiting rail overshoot to <130 V, preventing latch-up or damage. |
| Telecom Power Feeds | Renewable Energy Inverters |
Use Scenario: Shields PoE-powered Ethernet PHYs and DC-DC controllers from induced surges on 48 V DC distribution lines. IC Role / Device Role / Timing Role: Secondary protection stage after primary MOV, absorbing residual energy not diverted upstream. Use Value: 400 W peak power rating handles multiple 10/1000 µs transients without degradation, extending system field life. |
Use Scenario: Guards gate driver ICs and MCU reset lines in solar string inverters subject to lightning-induced common-mode surges. IC Role / Device Role / Timing Role: Fast-response clamping element on isolated 15 V auxiliary supply rails feeding optocouplers and level shifters. Use Value: Low RθJT (37 °C/W) maintains junction temperature below 150°C during repeated 3.2 A pulses, ensuring reliability in outdoor enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ78A-TB-E3/52 | Same 78 V VRWM, but SMB package (larger footprint, higher RθJA = 120 °C/W) | Better suited for lower-power, less thermally constrained boards where D-FLAT density is not required | Select when board layout allows larger pad area and thermal management prioritizes simplicity over miniaturization |
| 1.5SMC78A-Q | Higher 1500 W peak power, DO-214AB package, 137 V VC @ 10.9 A | Targets higher-energy transients (e.g., ISO 7637-2 pulse 5a); requires larger PCB real estate and heatsinking | Choose only when system-level testing confirms need for >400 W clamping capacity and space permits larger package |
Compared with SMBJ78A-TB-E3/52 and 1.5SMC78A-Q, P4SMAJ78ADF-13 delivers optimal balance of high surge robustness (400 W), ultra-compact D-FLAT packaging, and low thermal resistance - making it ideal for space-constrained industrial and automotive modules where both performance and layout efficiency are critical.
Availability
P4SMAJ78ADF-13 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, telecom power feeds, and renewable energy inverters requiring stable component supply and consistent surge protection performance across production batches.
Supply support for P4SMAJ78ADF-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, specializing in high-reliability protection, power management, and signal integrity solutions for industrial, automotive, and computing markets.
The P4SMAJ series belongs to Diodes' transient voltage suppressor portfolio, engineered specifically for high-efficiency, surface-mount surge protection in space-limited applications demanding IEC-compliant ESD immunity and repeatable clamping performance.
FAQ
What is the maximum allowable PCB temperature rise when P4SMAJ78ADF-13 dissipates 1.0 W continuously?
With a typical junction-to-terminal thermal resistance (RθJT) of 37 °C/W and a maximum junction temperature (TJ) of +150°C, the terminal temperature must remain ≤ +113°C to maintain safe operation. When mounted on a 1"×1", 2 oz copper pad, the device achieves this at TL = +75°C - meaning the PCB local temperature rise above ambient must stay below 38°C under full 1.0 W load.
Does P4SMAJ78ADF-13 support bidirectional transient suppression?
No. P4SMAJ78ADF-13 is a unidirectional TVS diode, configured with anode and cathode terminals to protect positive-going transients on grounded systems. For bidirectional protection (e.g., AC lines or floating signals), a separate symmetric device such as P4SMAJ78CA-13 must be used - it has identical ratings but dual avalanche structure.
How does the 10×1000 µs test waveform relate to real-world surge threats like lightning or load dump?
The 10×1000 µs waveform simulates medium-energy transients including indirect lightning strikes and automotive load dump events. While actual lightning may have longer tails, this standardized pulse validates the device's ability to clamp 3.2 A peak current at 126 V - matching the energy profile of ISO 7637-2 pulse 1 (inductive switch-off) and IEC 61000-4-5 combination wave (2 Ω source impedance).
Can P4SMAJ78ADF-13 be used in parallel to increase total surge current handling?
Not recommended. Due to parameter variation (VBR tolerance ±5%), paralleling units causes current imbalance - one device will conduct most of the surge, risking thermal runaway. For higher current needs, select a single higher-rated part (e.g., 1.5SMC78A-Q) or implement staged protection with upstream MOVs and downstream TVS devices.
P4SMAJ78ADF-13 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- 2-SMD, Flat Leads
- Series:
- P4SMAJ
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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):
- 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:
- D-Flat
P4SMAJ78ADF-13 FAQ
1.How can I place an order for P4SMAJ78ADF-13 through Aetrix?
Please submit a Request for Quotation (RFQ) for P4SMAJ78ADF-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 P4SMAJ78ADF-13 reliable?
The price and inventory of P4SMAJ78ADF-13 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for P4SMAJ78ADF-13 is usually 5 days.
3.What payment methods are accepted for P4SMAJ78ADF-13?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for P4SMAJ78ADF-13 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for P4SMAJ78ADF-13?
P4SMAJ78ADF-13 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your P4SMAJ78ADF-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 P4SMAJ78ADF-13?
For technical support, including P4SMAJ78ADF-13 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your P4SMAJ78ADF-13 requirements.
6.How does Aetrix verify that P4SMAJ78ADF-13 is sourced from the original manufacturer or authorized distributors?
All P4SMAJ78ADF-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 P4SMAJ78ADF-13 meets industry standards.
7.What is the process for return or replacement of P4SMAJ78ADF-13?
All P4SMAJ78ADF-13 units undergo pre-shipment inspection (PSI). If there is an issue with P4SMAJ78ADF-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 P4SMAJ78ADF-13 part is unused and in its original packaging.
Return procedure for P4SMAJ78ADF-13:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
P4SMAJ78ADF-13 Tags
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Diodes Incorporated
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Diodes Incorporated
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