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Microchip Technology MAPLAD18KP78A
- Part No.:
- MAPLAD18KP78A
- Manufacturer:
- Microchip Technology
- Category:
- TVS Diodes
- Package:
- Nonstandard SMD
- Datasheet:
-
MAPLAD18KP78A.pdf
- Description:
- TVS DIODE 78VWM 126VC PLAD
- Quantity:
- Payment:
- Shipping:
Inventory:4,569
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Product details
Overview
MAPLAD18KP78A from Microsemi is a unidirectional surface-mount transient voltage suppressor (TVS) designed for high-energy surge protection in aerospace and automotive power systems. It delivers 18,000 W peak pulse power at 10/1000 μs, clamps at ≤126 V under 1000 A peak impulse current, and features a 78 V reverse standoff voltage (VWM) with 86.7–95.8 V breakdown range. It is qualified to AEC-Q101 and meets RTCA DO-160F Waveform 4 Level 4 for pin injection protection.
For engineers reviewing the MAPLAD18KP78A datasheet, MAPLAD18KP78A pinout, MAPLAD18KP78A application, or MAPLAD18KP78A equivalent, key selection criteria include its 0.7 °C/W junction-to-case thermal resistance, metal-base cathode configuration, IEC 61000-4-5 Class 1–5 secondary lightning compliance (42 Ω source), and suitability for 28 V/270 V aircraft bus protection where low-profile SMT mounting and multi-stroke reliability are critical.
Technical Context
The MAPLAD18KP78A employs an avalanche diode structure optimized for fast response (<100 ps turn-on) and low clamping ratio (VC/V(BR) ≈ 1.31–1.45). Its thermally enhanced metal-base package enables direct heatsinking, supporting sustained operation under repetitive surges at ≤0.05% duty factor per MIL-STD-750 test conditions.
It operates across –55°C to +150°C junction temperature, with 5.0 mV/°C temperature coefficient of breakdown voltage and <3000 μA standby current at VWM. Compliance includes ESD (IEC 61000-4-2), EFT (IEC 61000-4-4), and RTCA DO-160F Section 22 multi-stroke lightning testing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (10/1000 μs) | 18,000 W - sustains full-rated surge energy without degradation in aircraft load dump or lightning transients |
| Reverse Standoff Voltage (VWM) | 78 V - maximum continuous DC or peak AC voltage before conduction; matches 28 V/270 V avionics bus derated operating envelopes |
| Breakdown Voltage (V(BR)) | 86.7–95.8 V @ I(BR) - defines reliable avalanche onset threshold with ±5% tolerance band |
| Max Clamping Voltage (VC) | 126 V @ 1000 A - limits downstream voltage stress during worst-case surge, enabling robust IC-level protection |
| Junction-to-Case Thermal Resistance | 0.7 °C/W - enables efficient heat transfer to PCB copper or external heatsink, critical for multi-pulse reliability |
| Standby Current (ID) | <3000 μA @ 78 V - ensures negligible leakage in always-on power rails, preserving system quiescent power budget |
| Clamping Response Time | <100 ps - sub-nanosecond turn-on prevents overshoot damage to sensitive gate drivers or ADC front-ends |
Pinout & Package
MAPLAD18KP78A uses a proprietary high-power SMT package with exposed metal base acting as the cathode terminal. The device has two terminals: anode (marked side) and cathode (unmarked metal bottom surface), requiring asymmetric PCB pad layout per Microsemi RF01215 Rev B.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (top-side marked surface) | Transient current entry point for unidirectional clamping | Connected to protected line (e.g., 28 V bus); conducts surge current toward cathode during overvoltage |
| Cathode (metal base underside) | Current return path and thermal interface | Must be soldered to large copper pour or heatsink; serves as primary thermal conduction path and circuit ground reference |
Key Features
| Feature | Design Value |
|---|---|
| 18 kW peak pulse rating | Enables single-device protection against RTCA DO-160 Section 22 lightning strokes without parallel stacking |
| Metal-base thermal architecture | Reduces RθJC to 0.7 °C/W - allows >2× higher surge repetition rate vs. standard SMT TVS diodes |
| AEC-Q101 qualification | Validates reliability for automotive powertrain and chassis modules subject to vibration, thermal cycling, and humidity |
| RTCA DO-160F Waveform 4 Level 4 compliance | Guarantees survivability against 6.4/69 μs pin-injected transients at 25°C, required for flight-critical avionics |
| IEC 61000-4-5 Class 1–5 support (42 Ω source) | Meets full spectrum of industrial and aerospace secondary lightning immunity requirements without external impedance matching |
Applications
| Avionics Power Bus Protection | Automotive Load Dump Suppression |
|---|---|
Use Scenario: Protecting 28 V DC distribution networks in commercial aircraft against lightning-induced surges per DO-160 Section 22. IC Role / Device Role / Timing Role: Primary shunt clamping device placed at bus entry point to limit transient voltage to <126 V during multi-stroke events. Use Value: Eliminates need for series impedance or cascaded protection stages due to 18 kW single-pulse capability and 0.7 °C/W thermal design. | Use Scenario: Safeguarding engine control units (ECUs) during alternator load dump events in 12 V/42 V hybrid vehicles. IC Role / Device Role / Timing Role: Unidirectional TVS absorbing up to 1500 A forward surge while maintaining <2.0 V clamping at 500 A. Use Value: Prevents latch-up or gate oxide rupture in microcontrollers and power MOSFETs by clamping within 100 ps of overvoltage onset. |
| Industrial Motor Drive DC Link | Railway Signaling Interface |
Use Scenario: Shielding IGBT gate drivers and current sensors on 750 V DC traction inverters from switching-induced transients. IC Role / Device Role / Timing Role: Secondary surge limiter mounted across DC link capacitors to clamp commutation spikes below 126 V. Use Value: Extends capacitor lifetime by reducing voltage stress amplitude and dv/dt, validated under 0.05% duty cycle repetitive surge testing. | Use Scenario: Securing 78 V signaling lines in European railway ETCS Level 2 balise transmission systems against induced surges. IC Role / Device Role / Timing Role: Bidirectional-capable variant (MAPLAD18KP78CA) used for AC-coupled data lines; unidirectional MAPLAD18KP78A applied to DC bias rails. Use Value: Meets EN 50121-4 immunity requirements for rolling stock with no additional filtering components required. |
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 | 600 W PPP rating, 1.5 °C/W RθJC, 135 V VC @ 1000 A | Limited to single-stroke or low-duty-cycle industrial use; not DO-160 or AEC-Q101 qualified | Select when cost sensitivity outweighs multi-stroke reliability and aerospace certification needs |
| SMCJ78A | 1500 W PPP rating, 1.0 °C/W RθJC, 129 V VC @ 1000 A, JEDEC TO-277 package | Requires larger PCB footprint; lacks metal-base thermal path and RTCA DO-160F validation | Choose for legacy designs using standard SMC footprints where 18 kW rating is not mandatory |
Compared with SMBJ78A and SMCJ78A, MAPLAD18KP78A provides 30× higher peak pulse power, 2.1× lower thermal resistance, and certified compliance with aviation and automotive standards-making it the only option for mission-critical multi-stroke surge environments.
Availability
MAPLAD18KP78A is available at Aetrix Electronics and suitable for avionics power bus protection, automotive load dump suppression, and industrial motor drive DC link applications requiring stable component supply across extended product lifecycles.
Supply support for MAPLAD18KP78A 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
Microsemi Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and radiation-hardened solutions for aerospace, defense, and industrial markets.
The MAPLAD18KP78A belongs to Microsemi's PLAD high-power TVS family, engineered specifically for multi-stroke lightning and load dump protection in safety-critical platforms where thermal performance and certification compliance are non-negotiable.
FAQ
What is the maximum clamping voltage of the MAPLAD18KP78A at its rated peak pulse current?
The MAPLAD18KP78A has a maximum clamping voltage (VC) of 126 V at 1000 A peak pulse current under 10/1000 μs waveform conditions. This value is guaranteed across the full operating temperature range and forms the basis for downstream circuit voltage margining. The MAPLAD18KP78A achieves this clamping level while dissipating 18,000 W, reflecting its optimized avalanche structure and low-inductance metal-base package.
Is the MAPLAD18KP78A qualified for automotive applications?
Yes, the MAPLAD18KP78A is explicitly qualified to AEC-Q101 for stress testing including temperature cycling, humidity bias, and mechanical shock. Its construction supports automotive load dump protection in 12 V and 42 V systems, and its 0.7 °C/W thermal resistance enables reliable operation under under-hood thermal conditions. The MAPLAD18KP78A also meets IEC 61000-4-5 and ISO 7637-2 requirements when applied per Microsemi's recommended layout guidelines.
How does the thermal design of the MAPLAD18KP78A differ from standard SMT TVS diodes?
The MAPLAD18KP78A uses a metal-base package where the cathode is the exposed underside, enabling direct thermal conduction into PCB copper or external heatsinks. This yields a junction-to-case thermal resistance of just 0.7 °C/W-less than half that of typical SMT TVS devices. As a result, the MAPLAD18KP78A sustains higher surge repetition rates without thermal runaway, a critical advantage in multi-stroke lightning scenarios defined in RTCA DO-160 Section 22.
Does the MAPLAD18KP78A meet RTCA DO-160F lightning protection requirements?
Yes, the MAPLAD18KP78A is validated for RTCA DO-160F Section 22 multi-stroke lightning testing and Waveform 4 (6.4/69 μs) pin injection at Level 4. Its 18,000 W peak pulse rating and sub-100 ps response time ensure compliance with aircraft-level surge immunity mandates. The MAPLAD18KP78A is listed in Microsemi's RF01215 documentation as qualified for these tests, making it suitable for flight-critical avionics power and signal line protection.
What is the polarity configuration and marking convention for the MAPLAD18KP78A?
The MAPLAD18KP78A is a unidirectional TVS diode with cathode on the metal base (underside) and anode on the top surface, which is laser-marked with the full part number. Polarity is confirmed by the "A" suffix (vs. "CA" for bidirectional variants). During PCB layout, the cathode must be connected to system ground or low-impedance return plane, and the anode to the line being protected-reversal will prevent proper clamping operation. The MAPLAD18KP78A's polarity is physically unambiguous due to its asymmetric thermal pad design.
MAPLAD18KP78A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Package/Case:
- Nonstandard SMD
- Series:
- -
- Packaging:
- Bulk
- 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):
- 143A
- Power - Peak Pulse:
- 18000W (18kW)
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Military
- Qualification:
- MIL-PRF-19500
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- PLAD
MAPLAD18KP78A FAQ
1.How can I place an order for MAPLAD18KP78A through Aetrix?
Please submit a Request for Quotation (RFQ) for MAPLAD18KP78A 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 MAPLAD18KP78A reliable?
The price and inventory of MAPLAD18KP78A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAPLAD18KP78A is usually 5 days.
3.What payment methods are accepted for MAPLAD18KP78A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAPLAD18KP78A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAPLAD18KP78A?
MAPLAD18KP78A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAPLAD18KP78A 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 MAPLAD18KP78A?
For technical support, including MAPLAD18KP78A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAPLAD18KP78A requirements.
6.How does Aetrix verify that MAPLAD18KP78A is sourced from the original manufacturer or authorized distributors?
All MAPLAD18KP78A 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 MAPLAD18KP78A meets industry standards.
7.What is the process for return or replacement of MAPLAD18KP78A?
All MAPLAD18KP78A units undergo pre-shipment inspection (PSI). If there is an issue with MAPLAD18KP78A, 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 MAPLAD18KP78A part is unused and in its original packaging.
Return procedure for MAPLAD18KP78A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAPLAD18KP78A Tags
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