DC–DC Converter-Aware Power Management for Low-Power Embedded Systems

Most digital systems are equipped with dc-dc converters to supply various levels of voltages from batteries to logic devices. DC-DC converters maintain legal voltage ranges regardless of the load current variation as well as battery voltage drop. Although the efficiency of dc-dc converters is changed by the output voltage level and the load current, most existing power management techniques simply ignore the efficiency variation of dc-dc converters. However, without a careful consideration of the efficiency variation of dc-dc converters, finding a true optimal power management will be impossible. In this paper, we solve the problem of energy minimization with the consideration of the characteristics of power consumption of dc-dc converters. Specifically, the contributions of our work are as follows: 1) We analyze the effects of the efficiency variation of dc-dc converters on a single-task execution in dynamic voltage scaling (DVS) scheme and propose the technique for dc-dc converter-aware energy-minimal DVS. 2) is then extended to embed an awareness of the characteristics of dc-dc converters in general DVS techniques for multiple tasks. 3) We go on to propose a technique called for generating a dc-dc converter that is most energy efficient for a particular application. 4) We also present an integrated framework, i.e., , based on and , which addresses dc-dc converter configuration and DVS simultaneously. Experimental results show that is able to save up to 24.8% of energy compared with previous power management schemes, which do not consider the efficiency variation of dc-dc converters.

I. Introduction

Almost all modern digital systems are supplied with power through dc–dc converters because high-performance CMOS devices are optimized to specific supply voltage ranges. DC–DC converters are generally classified into two types, namely: 1) linear voltage regulators and 2) switching voltage regulators, according to the circuit implementation. However, nontrivial power dissipation is unavoidable in both types of voltage conversion and directly affects battery life. Fig. 1 shows the path of current flow through a dc–dc converter from a battery. It is reported that there is always a nontrivial power loss in the converter, the amount of which is 10% to 40% of the total energy consumed in the system. Fig. 1.

Typical current flow path. Nontrivial power loss in the dc–dc converter results in a short battery life despite low power dissipation of the digital system.