Power Blocks Increase Efficiency and Power Density in Synchronous Bucks

The IRFH4251D (rated for 45A of current) and IRFH4253D (rated for 35A of current) from International Rectifier Corp. (IR) are the first of a family of power block devices for dc-dc synchronous buck applications including advanced telecom and netcom equipment, servers, graphic cards, desktop, ultrabook, and notebook computers. The 25V IRFH4251D and IRFH4253D feature IR’s latest generation silicon in a novel package that delivers benchmark power density in a 5x6 mm PQFN. The new power block devices feature an integrated monolithic FETKY®, and innovative package employing a leading-edge flipped-die technology that enables efficient dissipation of the heat from the source of the synchronous MOSFET directly to the ground layers of the PCB.

As a result of improved thermal performance and increased power density, one of the new 5x6 dual devices may replace two 5x6 standard single devices. The new package also utilizes IR’s proprietary single copper clip already employed in PowIRStage® and SupIRBuck® products, as well as an optimized layout that significantly reduces stray inductance to lower peak ringing. This allows the designer the option to use 25V MOSFETs in place of less efficient 30V devices.

“With its best-in-class silicon, and innovative features and packaging, the IRFH4251D and IRFH4253D power block devices offer industry leading power density for high performance DC-DC switching applications,” said Stéphane Ernoux, Director of Marketing, IR’s Power Management Devices Business Unit. “The devices employ a more efficient layout that will define the new industry standard for DC-DC dual MOSFETs,” he added.

The IRFH4251D and IRFH4253D are optimized for 5V gate drive to work with any controller or driver. As a result, they offer design flexibility while delivering higher current, efficiency, and frequency capability in a small footprint compared to alternative approaches using two discrete 30V power MOSFETs. Pricing for the IRFH4253D and IRFH4251D begins at US $0.89 and US $1.29 respectively in 10,000-unit quantities. Production orders are available immediately.