April 26, 2006
Power Management for Mobile Devices
Unified Power Management Architecture
Traditional power management techniques as described above have commonly been implemented in wireless handsets, personal digital assistants (PDAs), laptop computers and other power-sensitive devices. Definitely these techniques will continue to be applied, but the industry's current trends necessitate comprehensive and aggressive solutions that address both power and performance. For high performance, power-sensitive applications, power reduction is only half the challenge. The imperative today and moving into the future is to provide higher performance but consuming less power per function. The sophisticated applications that are converging on mobile handsets operate at much higher frequencies than voice communications. For example, simple audio on a wireless mobile device typically operates at less than 20 MHz, whereas a video application may require a frequency of 200 MHz or more. Just managing the hundreds of thousands of pixels in a high-resolution video display generates a tremendous amount of power-consuming processing cycles. Only creative new power reduction techniques that cross functional blocks and include multiple processing cores will allow the system to adapt itself dynamically to achieve high performance with less power.
Dynamic power management did not prove enough to meet the goal of delivering maximal performance at minimal power. A system-wide perspective is required to meet this goal. SmartReflex technology from Texas Instruments offers such a perspective by optimizing power consumption at different levels. Thus offering maximal performance at minimal power drain.
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Figure 2: SmartReflex technology.
SmartReflex technologies are comprised of three facets: first, silicon intellectual property (IP); second, techniques that can be applied at the SOC design level; and last, system software that manages many of the hardware-enabled SmartReflex technologies, which interface seamlessly to other power management techniques based in operating systems (OS) or third-party software subsystems (see Figure 2). SmartReflex technologies cross many of the traditional boundary lines such as the distinction between processing cores. First- and second-generation power management solutions were, by and large, vendor-specific and limited in their scope. They could only be applied to certain functional blocks or specific cores. As a result, they only addressed a small portion of the device's power budget. In contrast, SmartReflex technologies support multiple cores, hardware accelerators, functional blocks, peripherals and other system components. In addition, SmartReflex system-level technologies are open to OS-based and high level power management algorithms so that a collaborative and co-operative environment with regards to power and performance can be developed.
Of course, such a powerful technology solves many problems of power management at system level. A radio interface driven and application optimized high-level algorithm will perfectly complement such a technology and build a strong and effective power management system. For example, a methodology can be developed for GSM phones where modem specific hardware domains will go idle when the phone is in "GSM idle" mode and will come back to active state when the phone will enter into "GSM dedicated" mode. Dependeing on the radio interface and applications (for example, Camera Preview or MP3 player) requirements various sleep states can be defined. An efficient state transition logic with such states defined coupled with a system-level foundation like TI's SmartReflex can solve many power management problems and provide system designers a peace of mind. 
Previous Page |
1 Introduction
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2 Silicon Techniques for Power Management
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3 Software Techniques for Power Management
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4 Unified Power Management Architecture
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5 Conclusion
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