System level trade-offs of microprocessor supply voltage reduction

This paper examines the impact of decreasing microprocessor supply voltage on system efficiency and performance. While digital designers can decrease power consumption in a microprocessor by lowering its supply voltage, efficiency and performance trade-offs arise in the power supply that offset the power reduction. Conduction losses and switching losses in a buck converter are the primary losses in a switching voltage regulator, and they tend to increase with decreased output voltage. A lower supply voltage can cause control challenges, introduce sensitivity limitations, and reduce overall system efficiency. An efficiency and performance analysis is presented, based on a 12 V board-level power source employed with a low-output-voltage buck converter. The analysis demonstrates system-level limitations of supply voltage reduction.