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Control IC increases multiphase converter efficiency

Posted: 08 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:IR3084? IR3084U? multiphase converter chipset? XPhase control IC? International Rectifier?

XPhase control IC

International Rectifier (IR) has expanded the IR XPhase family of scalable multiphase converter chipsets with the IR3084 and IR3084U XPhase control ICs. The new products are designed to be used with the company's existing IR3086A phase IC and companion DirectFET power MOSFETs such as the IRF6617 and IRF6691 to achieve as much as three percent higher efficiency in 130A applications with seven phases.

The IR3084 supports Intel VR10.x and VR11 microprocessor core power requirements, while the IR3084U is a universal voltage identification (VID) device for VR10.x and VR11 as well as AMD Opteron VID codes and start-up sequences.

The XPhase chipset aims to increase power density and efficiency in desktops, servers, voltage regulator modules and embedded systems. By increasing the number of phases from five to seven, the current in each phase is decreased, and enables the use of smaller inductors and reduced output capacitors. This is said to reduce footprint size from 3,200mm2 to 2,400mm2, a 25 percent reduction in board area.

The IR3084 solution, including the IRF6617 and IRF6691 power MOSFETs, achieves 88 percent efficiency at full load current and is said to eliminate the need for a heatsink.

"Removal of the regulator heat sink reduces manufacturing costs and improves airflow to the CPU in low-profile 1U and blade servers," said Stephen Tsang, senior vice president of sales at IR. "This improves system performance and long-term product reliability."

Both control ICs include 0.5 percent overall system accuracy and differential remote voltage sensing. The ICs offer a programmable 150kHz to 1MHz oscillator, remote temperature sensing and lossless DCR current sensing with programmable hiccup over-current protection. The IR3084U includes a VID select pin which allows for simple migration from AMD to Intel VID codes.

XPhase is IR's distributed multiphase architecture that consists of control ICs and phase ICs that communicate using a simple five-wire bus scheme. Phases can be added or removed without changing the fundamental design. The five-wire analog bus consists of bias voltage, phase timing, average current, error amplifier output and VID voltage.

The IR3084 and IR3084U XPhase control ICs are available immediately. Pricing is $1.60 each for the IR3084MPbF and the IR3084MTRPbF (tape and reel), and $1.75 each for the IR3084UMPbF and the IR3084UMTRPbF (tape and reel). Pricing is in 10,000-unit quantity. Prices are subject to change. The devices are Pb-free and RoHS compliant.

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