Power Management Challenges for Portable Applications

Spiraling energy costs and increased awareness of environmental issues such as global warming are creating new opportunities for energy efficiency in the semiconductor industry. Most electronic devices on the market today simply don’t last as long as they should. As consumers move toward a more mobile lifestyle, the need for power management ICs is growing. There is a great need for chips that can effectively control automotive systems to reduce electronic emissions and get longer use out of other consumer products that help us reduce power consumption in our daily lives.

Manufacturers of portable consumer electronic devices have always been challenged to develop cost-effective, high-performance, multi-functional solutions with longer battery life. Manufacturers also have to shorten development time to be the first to launch new products on the market. By developing ultra-low power codecs with embedded mini DSPs and powerful graphical programming tools, manufacturers can meet various complex requirements. Many new generation ultra-low power codecs can run analog and digital cores from a single 1.5V to 1.8V power supply in low-power operating mode. For example, in some audio applications, it is possible to reduce power consumption by running the digital core at a low voltage of 1.26V (as low as 0.6V to 0.7V for netbooks).

Although many devices have low-power operating modes, additional power scaling options allow designers to customize their power consumption based on individual configuration and processing options. This allows designers to dynamically optimize power scaling to minimize power consumption based on input and output channels, output drive requirements, sampling rate, desired SNR performance for input and output, and processing features used. Power scaling can make a huge difference in the battery life of portable audio and video devices. The integration of ultra-low power data conversion and low-power signal processing into a single chip can bring significant low-power implementation possibilities in traditional system architectures that include application processors and codecs. In these architectures, ultra-low power codecs can implement some or all of the audio processing functions of the application processor. One of the many powerful tools for achieving longer battery life is an ultra-low power codec with an embedded mini DSP. These devices and their powerful graphical programming tools provide low-power audio solutions for many portable audio processing and communication system architectures.

In the near future, we will have many netbooks and laptops that can work all day without recharging. There are three main challenges in designing portable product features: understanding the overall system power budget; designing efficient power converters and controllers to minimize losses; and interactively managing the system's power requirements.

The portable consumer electronics market is highly competitive and is growing rapidly. Fast time to market and ultra-low power consumption allow manufacturers to develop differentiated products while shortening their design cycles. The new generation of portable consumer devices (such as wireless headsets, smart phones, PDAs, and media players) boasts more features, higher performance levels, and smaller solution sizes. Due to their latest features, these devices are all power hungry. Examples include cameras with 3 million pixel resolution or more, high power flash LED or Xenon lamps, advanced audio and speaker capabilities, GPS and phones with high resolution LCD-TV displays. Designers are challenged with both static and dynamic power requirements. As portable devices become more and more versatile, power requirements are rapidly increasing. As a result, battery life is getting shorter and shorter.

As ICs become more integrated and feature-rich, more power rails are needed or the same power rails require higher supply currents. Most portable consumer applications use standard high-performance lithium-ion batteries (generally in single-cell configurations). With this limited power, manufacturers must understand whether consumers prefer multi-function applications with shorter battery life or control the number of features and their application's functional requirements. Today's consumers want high-end devices with long battery life. To break the power consumption dilemma in portable devices, many technical approaches are used. To meet the functional requirements of processors, IC manufacturers have taken the lead in reducing power consumption at specific performance levels. Meeting power requirements and addressing low-power challenges requires the development of new processing technologies. For example, one approach is called  SmartReflex  , which is used in DSPs and TI's OMAP processors. It can reduce total power consumption, optimize system performance, and increase battery life. Using many intelligent and adaptive hardware and software methods, it can dynamically control voltage, frequency, and power consumption based on device activity, operating mode, and temperature. The power management design provides the necessary voltage rails and adjusts the voltage and current based on the processor's needs. All processors and power management devices typically use light load or standby mode if the application is turned off or in a predefined power consumption "power saving" mode. In this way, the current voltage level is reduced and the current consumption is minimized. The IC itself will consume as little current as possible, down to a few microamps, in different operating states. Once the portable device design is completed, there is almost nothing that can affect the voltage rail layer.

Some serial interfaces of integrated power management devices bring some new layers of influence. In addition, software-controlled power management and monitoring can be implemented, and multiple power-saving modes can be used between existing full load and system standby modes. Dynamic voltage scaling (DVS) using the I2C interface has two different speed options: standard 100kbps and fast 400kbps. After using this method in a discrete low-power DC/DC converter or power management unit, designers can dynamically and accurately influence the output voltage of the power management device and adjust the core supply voltage of all processor units. This design allows the system to meet precise performance requirements without sacrificing overall performance. As a result, the lowest power consumption is used for each operating state of the processor mode, thereby extending the battery, reducing heat dissipation per device, and improving overall system performance. Programmable DC/DC converters help extend the battery life of 3G smart phones, PDAs, digital cameras and other portable applications. Another way to reduce power consumption using the I2C interface is to use some more complex devices, such as: TPS65020 , etc. It is a highly integrated PMU with six output channels, three low-power DC/DC converters (with up to 97% efficiency) and three LDOs. Different components (such as all three LDOs or DC/DC converters of this IC) can be turned off/on through I2C to reduce the power consumption and heat dissipation of the entire PMU.

By turning off different components, quiescent current consumption can also be reduced. In addition to some of the power saving schemes already discussed, new manufacturing technologies will play a key role in the future. The amount of communication between the DSP core and its discrete analog power consumption elements will increase to allow flexible on-time power adjustment and software-controlled power consumption schemes. All of these improvements and methods must work together to optimize performance and maximize battery life to benefit consumers.

In the future, consumers will demand high-quality mobile video/audio entertainment through smaller, lighter portable devices that require more features and higher-density storage, pushing semiconductor manufacturers to consider new design and manufacturing solutions. We must change not only what we do, but how we do it. Only by clearly understanding where we are and how we got there can we find the right path through the future. It is important to recognize that there is no silver bullet to solve the problem of high power requirements. Instead, efforts should be focused on tools that can help system designers understand the performance and power implications. It is time to provide a system-level solution rather than a component-level solution, and TI is uniquely positioned to meet this market demand.