International Rectifier, introduced a breakthrough surface-mount power MOSFET packaging technology called DirectFETtm power packaging. The DirectFET packaging is the first surface-mount package in an SO-8 footprint designed for efficient top-side cooling. In combination with improved bottom-side cooling, the new package can be cooled on both sides to cut MOSFET part count by up to 60% and shrink board space by as much as 50% compared to an SO-8 type solution.This effectively doubles current density, or amps per square inch. A dual-side cooled DirectFET chipset enables DC-DC converters capable of 30A per phase with a single pair of MOSFETs, at a lower total system cost when compared to single-side cooled SO-8 designs and at a current density of over 24 amps per square inch, double that of the standard SO-8 solution. The new devices are designed for high-frequency, high-current DC-DC converters used to power next generation Intel(®) and AMD microprocessors found in high-end notebooks and servers, as well as advanced telecom and datacom systems.
DirectFET packaging can be leveraged to reach high current levels without paralleling MOSFETs, adding an additional phase in multiphase converters, using heat pipes or fans, or adding copper throughout the whole PCB, all of which reduce current density and add system cost. When comparing DirectFET solutions to these alternative designs, DirectFET is the most economical solution, with at least a 50% reduction in the cost of heat removal, and provides the smallest space requirement.
May.2002
International Rectifier
