Microchip Technology MPLAD18KP85CA

Overview

MPLAD18KP85CA from Microsemi is a bidirectional surface-mount transient voltage suppressor (TVS) designed for high-energy surge protection in aerospace and automotive systems. It delivers 18,000 W peak pulse power at 10/1000 μs, clamps transients to ≤137 V at 1000 A, and features a 78 V reverse standoff voltage (VWM) with ±5% breakdown tolerance (94.4–104.0 V). It is qualified to AEC-Q101 and meets RTCA DO-160F Level 4 pin injection for Waveform 4.

For engineers reviewing the MPLAD18KP85CA datasheet, MPLAD18KP85CA pinout, MPLAD18KP85CA application, or MPLAD18KP85CA equivalent, this device is selected for secondary lightning protection per IEC 61000-4-5 (42 Ω, 12 Ω, and 2 Ω source impedances), ESD/EFT immunity per IEC 61000-4-2/4-4, and multi-stroke lightning compliance per RTCA DO-160 Section 22 in aircraft avionics and engine control units.

Technical Context

The MPLAD18KP85CA operates as a bidirectional avalanche diode-based TVS, leveraging silicon junction design to achieve sub-5 ns response time and low clamping ratio (VC/V(BR) ≈ 1.37). Its thermal resistance junction-to-case is 0.7 °C/W, enabling efficient heat transfer to PCB copper when mounted per recommended pad layout.

It supports dual-standard surge immunity: IEC 61000-4-5 Class 1–5 (42 Ω), Class 1–4 (12 Ω), and Class 2–3 (2 Ω); and RTCA DO-160F Waveform 4 (6.4/69 μs) Level 4 up to 200 V VWM variants - all confirmed for MPLAD18KP85CA in Rev B documentation.

Key Specifications

Pinout & Package

Package: Surface-mount PLAD (Plastic Low-profile Anode/Cathode) - void-free UL94V-0 epoxy body, tin-lead or RoHS-compliant matte-tin plating, metal base cathode (bidirectional symmetry eliminates polarity marking).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Compared with SMBJ85CA and SMCJ85CA, the MPLAD18KP85CA provides 30× and 12× higher peak pulse power respectively, enabling compliance with RTCA DO-160F Section 22 multi-stroke lightning and IEC 61000-4-5 Class 4/5 - making it uniquely suited for aerospace and high-reliability automotive powertrain applications.

Availability

MPLAD18KP85CA is available at Aetrix Electronics and suitable for avionics subsystems, automotive powertrain electronics, industrial motor drives, and railway signaling equipment requiring stable component supply across extended product lifecycles.

Supply support for MPLAD18KP85CA 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, RF, and timing solutions for aerospace, defense, and industrial markets.

The MPLAD18KP85CA belongs to Microsemi's PLAD-series high-power TVS family, engineered specifically for multi-stroke lightning survivability and DO-160F compliance in safety-critical airborne electronics.

FAQ

What is the clamping voltage of the MPLAD18KP85CA at its rated peak pulse current?

The MPLAD18KP85CA has a maximum clamping voltage (VC) of 137 V at 1000 A peak pulse current under 10/1000 μs waveform conditions. This value is measured per Figure 3 in RF01215 Rev B and defines the upper voltage limit imposed on protected circuitry during worst-case surge events. The clamping performance is guaranteed across the full operating temperature range and forms the basis for downstream IC overvoltage margin calculations in the MPLAD18KP85CA design-in process.

Is the MPLAD18KP85CA suitable for RTCA DO-160F Section 22 lightning testing?

Yes, the MPLAD18KP85CA is explicitly validated for RTCA DO-160F Section 22 multi-stroke lightning testing. Documentation confirms its capability to meet Level 4 pin injection for Waveform 4 (6.4/69 μs) and full compliance with aircraft lightning zoning requirements. Its 18,000 W peak pulse power rating, low RθJC (0.7 °C/W), and bidirectional architecture make the MPLAD18KP85CA a preferred solution for flight-critical avionics where repeated surge endurance is mandatory.

Does the MPLAD18KP85CA require moisture preconditioning before reflow soldering?

No, the MPLAD18KP85CA is rated Moisture Sensitivity Level 1 per IPC/JEDEC J-STD-020B, meaning it does not require dry pack packaging or baking prior to surface-mount assembly. This eliminates moisture-related popcorning risk and simplifies manufacturing flow - a key advantage for high-reliability producers using the MPLAD18KP85CA in aerospace and defense production lines.

How does the bidirectional construction of the MPLAD18KP85CA affect PCB layout?

The bidirectional construction of the MPLAD18KP85CA eliminates polarity sensitivity: both terminals are functionally identical, and the metal base serves as a symmetrical current path. This allows placement without orientation constraints - unlike unidirectional TVS diodes - reducing assembly errors and enabling flexible routing in dense avionics layouts. The MPLAD18KP85CA's symmetric pinout also simplifies layout for differential buses such as RS-485 or MIL-STD-1553.

What is the thermal resistance junction-to-ambient (RθJA) for the MPLAD18KP85CA?

The MPLAD18KP85CA has a thermal resistance junction-to-ambient (RθJA) of 50 °C/W when mounted on FR4 with the recommended pad layout per RF01215 Rev B. However, its much lower junction-to-case resistance (RθJC = 0.7 °C/W) indicates that effective thermal management depends primarily on copper area and thermal vias beneath the metal base. For sustained surge duty, the MPLAD18KP85CA must be mounted on ≥2 in² of 2-oz copper with ≥6 thermal vias to maintain safe junction temperatures.