Digital Power Forum Closing Day Includes Case Studies from Ericsson and AMD
During the final sessions in the Data Center Track at the 2006 Digital Power Forum, Ericsson Power Modules presented a case study of performance improvements in servers enabled by digital loop control techniques while Advanced Micro Devices (AMD) presented a study of optimizing the power consumption of high-performance servers in a data center environment.
"Just in California alone, data centers consume up to 375MW of electricity, accounting for about 5,200 barrels of oil daily," stated Brent Kerby, Product Manager with AMD. "Server power is the critical element in this energy consumption. Data center power consumption has grown from about 40W/square foot in the 1990s to almost 500W per square for today. The trend of increasing power consumption cannot continue indefinitely," Kerby concluded.
Today, 1.4kW of power are wasted for every kilowatt of power consumed in computing activities. The sources of waste energy include back-up power systems, lighting, cooling and general power conversion inefficiencies. According to Kerby, next generation AMD Opteron™ processors have planned upgrade path to quad-core within existing power/ thermal envelops.
Key processor advances that are helping to control power consumption are numerous and include: Silicon-on-insulator CMOS processes that reduce leakage currents. Integrated memory controllers that can save up to 22W per processor. Advanced power management within the processor that reduces power consumption based on workload, reducing overall power consumption by up to 75%. Finally, AMD's "Direct Connect" architecture provides faster CPU-to-CPU connections with no increase in power consumption.
While Kerby focused on data center and processor architectures for power savings, Torbjorn Holmberg, with Ericsson Power Modules presented a comparative study of digital and analog control loops employing two identical power stages. The power module used in this case study was an Ericsson PMH8918L 18A non-isolated synchronous buck regulator point-of-load (POL) regulator with a 12V input and a programmable output voltage.
"The comparison results can be summarized as follows: The electrical performance, including efficiency, of the digitally controlled regulator is equal to or better than the analog version. The digital solution results in more than a 60% reduction in parts count and this increased integration will reduce the cost of the regulator," stated Holmberg. "The reduced parts count will result in a smaller POL and will also increase the predicted reliability of the device. Digital control can be used as an enabling technology to offer cost, reliability and power density improvements to the end user with no additional design effort required from the system designer," he concluded.
