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Chipset cuts convertor losses

An International Rectifier product story

Edited by the Electronicstalk editorial team Sep 28, 2004

A new chipset provides control and synchronous switching for high-frequency DC/DC convertors powering next-generation Intel and AMD processors in high-end advanced servers and desktop computers.

International Rectifier has introduced a control and synchronous switching chipset for high-frequency DC/DC convertors powering next-generation Intel and AMD processors in high-end advanced servers and desktop computers.

Other applications include point-of-load (POL) DC/DC conversion in telecomms and datacomms systems.

The chipset pair delivers 84.5% efficiency at 90A in a four-phase 1U (1.75in height) VRM outline system switching at 750kHz per phase and 87% efficiency at 150A in an eight-phase embedded VRD10.2 design switching at 400kHz per phase.

The first device is the monolithic IRF6691 DirectFETKY, which integrates a Schottky diode and synchronous MOSFET into a single package to enable an efficiency improvement of 1.1% at 1MHz per phase at full load compared with other existing top-performing 20V synchronous FETs on the market when using the same control FET.

The IRF6691 also features a typical on-resistance of 1.2mohm at 10V (1.8mohm at 4.5V) and a typical reverse recovery charge of 26nC, providing the best thermal performance with lower reverse recovery losses and reduced overall part count.

The second device is the IRF6617 DirectFET HEXFET control MOSFET.

Specifically tailored for control FET switching, the IRF6617 features a very low total gate charge (11nC), delivering a 33% reduction in on-resistance times gate charge product of 87mohm-nC at 4.5V, compared with previous 30V devices.

Both devices feature International Rectifier's patented DirectFET packaging technology that presents a whole new set of design advantages not previously delivered by standard plastic discrete packages.

By deploying a new dual-side cooling design, the DirectFET power MOSFET family effectively doubles the current handling capacity of high frequency DC/DC buck convertors powering advanced processors.