Digital Multiphase Architecture Powers Multi-GHz CPUs

May 1, 2003 12:00 PM
By Ashok Bindra, Editor, Power Electronics Technology

PowerCode, Primarion and Intersil Corp.'s joint development efforts on digital multiphase architecture, bore fruit recently when the companies announced parts based on its design to power new-generation multi-GHz microprocessors. The companies have separately introduced chipsets comprised of a digital controller and a power stage. They have also created a development platform for engineers to experiment with the architecture.

Primarion's digital controller and power stage ICs are called PX3530 and PX3510, respectively. Intersil's identical parts are labeled ISL6590 for the digital controller and ISL6580 for the power stage. Primarion chips are pin and function interchangeable with Intersil ICs. Although the initial thrust for PowerCode is for high-end servers, it's aimed at other servers and workstations.

PowerCode meets the strictest dc load line accuracy, stability, and transient response requirements of multi-GHz CPUs. The present core voltage of 1.5V is moving downward to 0.5V, as core static current tends to go from current 70A to over 200A in a few years. Moreover, transient current requirements are rapidly advancing from today's 100A/µs to 500A/µs.

Primarion's PowerCode digital controller PX3530 drives two to six phases via the power stage ICs (figure) and permits digital programmability using a GUI interface. Thus, it can be optimized for parameters such as loop response, number of phases, phase frequency, input voltage, maximum load, and passive filter component characteristics using software. To meet transient-state current demand, it offers active transient response (ATR) mode. The programmable switching frequency range for the controller is 250 kHz to 1 MHz. In addition to rapid optimization, the software enables diagnosis of system performance. Data generated by the software can be ported to PSpice or Matlab simulators for detailed analysis. The controller is housed in a 64-pin QFN plastic package.

Digitally interfaced to the controller, Primarion's PX3510 is a high-side FET/driver combination that provides high current per converter phase at high switching frequency. It integrates on-chip two MOSFET drivers and a p-channel high-side MOSFET, as well as voltage and current 6-bit analog-to-digital converters (ADCs) and a window comparator. Other features include thermal shutdown, peak current limit, undervoltage detection, and overvoltage protection. Capable of up to 25A of continuous output current, the output voltage regulation range for the power stage is 0.8375Vdc to 1.85Vdc. It also supports 5-bit and 6-bit VID codes. The power device comes in a 56-pin QFN plastic package.

Primarion, Tempe, Ariz; www.primarion.com CIRCLE 349 on Reader Service Card

Intersil Corp, Palm Bay, Fla.; www.intersil.com CIRCLE 345 on Reader Service Card

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