IR's New XPhase® Chipset Enables Smaller, Simpler Design While Delivering Best-in-Class Efficiency for Next-Generation AMD Processors

May 25, 2010 | Technology Media

EL SEGUNDO, Calif. — International Rectifier, IR® (NYSE: IRF), a world leader in power management technology, today introduced the IR3521 and IR3529 XPhase® chipset solution offering best-in-class efficiency over the entire load range for next-generation high performance AMD processors.

The IR3521 XPhase control IC supports high speed (HS) I²C serial communications to provide overall system control, interfacing with any number of phase ICs, each driving and monitoring a single phase. When used with the IR3529 XPhase phase IC, the IR3521 enables phase dropping to significantly improve the light load performance of the power supply.

The IR3529 phase IC features a Power State Indicator (PSI) to maximize efficiency at light loads, as well as enhanced driver capability and reduced non-overlap time. Turbo is also included to improve load turn-on response. In addition, the IR3529 incorporates novel features that greatly enhance the transient response of the converter to reduce the overall solution size and cost.

"Combined with our DirectFET® MOSFETs, our new XPhase chipset for AMD processors delivers a power supply that is smaller, more flexible, and easier to design while providing superior efficiency over the entire load range compared to conventional approaches," said Deepak Savadatti, senior director, IR's Multiphase Products, Enterprise Power Business Unit.

The IR3521 control IC provides outputs for both the VDD core and VDDNB auxiliary planes required by the AMD CPU and features high speed error amplifiers with wide bandwidth of 20MHz and fast slew rate of 10V/us. Remote sense amplifiers provide differential sensing and require less than 50uA bias current. In addition, the new device offers a high level of programmability including programmable Dynamic VID slew rates, VID Offset (VDD output only), output impedance (VDD output only) and dynamic OC for IDD spike.

The IR3529 phase IC features anti-bias circuitry, 7V/4A gate drivers (6A GATE L sink current) and supports loss-less inductor current sensing and a converter output voltage up to 5.1 V. The new device also implements cycle-by-cycle over-current protection to resolve high repetition load transients.

A reference design is available upon request. Contact For datasheets use the Part Number links above.

XPhase is IR's distributed multiphase architecture that consists of control ICs and phase ICs that communicate using a simple six-wire bus scheme. Phases can be added or removed without changing the fundamental design. The six-wire bus consists of a three-wire digital phase timing bus, an average current, an error amplifier output and a VID voltage. By eliminating point-to-point wiring between the control and the phase ICs, the six-wire bus shortens interconnections, and reduces parasitic inductance and noise. This simplifies PCB layout and provides a more robust design.

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