Microchip Technology MPLAD18KP28A

Overview

MPLAD18KP28A from Microsemi is a unidirectional surface-mount transient voltage suppressor (TVS) designed for high-energy surge protection in aerospace, automotive, and industrial power systems. It delivers 18,000 W peak pulse power at 10/1000 μs, clamps at ≤45.5 V under 396 A peak impulse current, and features a 28 V reverse standoff voltage (VWM) with 31.1–34.4 V breakdown range. It meets RTCA DO-160F Waveform 4 Level 4 and IEC 61000-4-5 Class 1–5 secondary lightning protection requirements.

For engineers reviewing the MPLAD18KP28A datasheet, MPLAD18KP28A pinout, MPLAD18KP28A application, or MPLAD18KP28A equivalent, this page provides verified electrical parameters, thermal resistance (RθJC = 0.7 °C/W), RoHS-compliant packaging, polarity identification (cathode on metal base), and application-specific derating guidance for multi-stroke lightning and load dump scenarios.

Technical Context

The MPLAD18KP28A operates as a silicon avalanche diode configured for unidirectional clamping, with junction-to-case thermal resistance of 0.7 °C/W enabling efficient heat transfer to PCB copper or heatsink. Its low clamping ratio (VC/V(BR) ≈ 1.43) ensures rapid voltage limiting during transients up to 1000 A, validated per AEC-Q101 and MIL-PRF-19500 screening options.

It supports IEC 61000-4-2 ESD (±30 kV air), IEC 61000-4-4 EFT (40 A), and IEC 61000-4-5 surge testing with 2 Ω, 12 Ω, and 42 Ω source impedances - meeting Class 2–4 at 2 Ω and Class 1–5 at 42 Ω. Pin injection immunity per RTCA/DO-160F Waveform 4 (6.4/69 μs) is certified to Level 4.

Key Specifications

Pinout & Package

Surface-mount package with metal base cathode terminal and molded thermosetting epoxy body (UL94V-0). Cathode is electrically connected to the exposed metal underside; anode is accessible via top-side metallized terminals. Designed for thermal conduction through PCB copper or external heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ28A and SMCJ28A, the MPLAD18KP28A delivers 30× higher peak power, 4× lower thermal resistance, and full DO-160F Waveform 4 Level 4 certification - making it the only viable option for certified aerospace power entry protection.

Availability

MPLAD18KP28A is available at Aetrix Electronics and suitable for aerospace power distribution, automotive load dump protection, and industrial motor drive DC bus applications requiring stable component supply across extended product lifecycles.

Supply support for MPLAD18KP28A 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, timing, and radiation-hardened solutions for aerospace, defense, and industrial markets.

The MPLAD18KP28A belongs to Microsemi's PLAD high-power TVS family, engineered specifically for multi-stroke lightning and load dump protection in safety-critical platforms where failure is not an option.

FAQ

What is the clamping voltage of MPLAD18KP28A at its rated peak pulse current?

The MPLAD18KP28A has a maximum clamping voltage (VC) of 45.5 V when subjected to its rated peak pulse current (IPP) of 396 A under 10/1000 μs waveform conditions. This value is measured at the device terminals and reflects worst-case performance across temperature and manufacturing variation. The MPLAD18KP28A maintains this clamping performance over its full operating junction temperature range of –55°C to +150°C.

Is MPLAD18KP28A suitable for bidirectional signal line protection?

No, the MPLAD18KP28A is a unidirectional TVS diode, with cathode on the metal base and anode on the top metallization. For bidirectional protection, Microsemi offers the MPLAD18KP28CA variant. Using MPLAD18KP28A on AC or bipolar signal lines would result in forward conduction during negative half-cycles, potentially damaging the device or circuit. Always verify polarity alignment before integrating MPLAD18KP28A into any design.

Does MPLAD18KP28A require a heatsink for standard operation?

The MPLAD18KP28A does not require an external heatsink for single-event surge suppression, but its 0.7 °C/W junction-to-case thermal resistance is intended for direct thermal coupling to PCB copper or a heatsink during repetitive or high-duty-cycle transients. For applications with >0.05% duty factor or ambient temperatures above 70°C, thermal design using ≥2 in² of 2 oz copper is recommended to maintain TJ < 150°C. The MPLAD18KP28A's metal base must be soldered to this thermal plane.

What certifications and standards does MPLAD18KP28A meet?

The MPLAD18KP28A is tested per AEC-Q101 for automotive reliability and supports MIL-PRF-19500 upscreening. It meets RTCA DO-160F Section 22 Waveform 4 Level 4 (6.4/69 μs), IEC 61000-4-2 (±30 kV contact), IEC 61000-4-4 (40 A EFT), and IEC 61000-4-5 Class 1–5 (42 Ω source). These certifications are documented in Microsemi's RF01215 Rev B datasheet and apply specifically to the MPLAD18KP28A, not just the family.

How is polarity identified on the MPLAD18KP28A package?

Polarity is defined by physical construction: the cathode is the exposed metal base (underside) of the MPLAD18KP28A, while the anode connects to the top-side metallized terminals. The device marking "MPLAD18KP28A" appears on the top surface, and no additional polarity symbol is printed. Correct orientation requires the metal base to be soldered to the circuit ground or low-impedance return path - reversing polarity will cause immediate forward conduction and failure under normal operating voltage.