Courtesy : www.ti.com

Energy efficiency innovation

Many consumers probably don’t even realize the actual energy cost for mobile devices. In 2006,
it was estimated that the average customer of mobile operator NTT DoCoMo, one of the largest
wireless providers in Japan, used about 70 watt hours (Wh) per day per mobile phone,
1
which is
much more consumption than the four to five Wh the phone battery could provide.
Figure 1 demonstrates the expected data traffic growth through 2020 for the U.S.2
Traffic is
generated by phone call, text messaging, Internet data and so on. All these exchanges add up
to trillions of bits (terabits) being moved. It takes large amounts of energy to move this data.
Sending a terabit/s is estimated to require a quarter to half of a mega-watt hour. While we
want the ability to send and receive more data, corporations and consumers are becoming
more environmentally conscious. Building more electricity generation plants is not the answer.
Rather, in order to support this growth in data traffic, more efficient use of energy must
be developed.
WHITE PAPER
Introduction
Technology innovation is pervasive and constant.
It has revolutionized the world, through the
era of personal computers, the explosion of
the Internet, and today’s mobility and
connectivity in our homes, cars and literally
everywhere. Vanishing are the days when access
to a wall outlet is the only way to charge a device.
Consumers demand the latest and greatest in
mobility and functionality. We expect devices
to run the most complex functions using the
least amount of battery (or energy) possible.
Innovations in energy efficiency and low
power are enabling these demands today
and are critical to sustain future advancements in emerging applications in areas
like cloud computing, healthcare, security,
transportation and more.
Driving innovation in energy
efficiency and low power
Paul Brohlin
IC Design Engineer,
Motor Lab,
Texas Instruments
Dave Freeman
Chief Technologist,
Power Supply Solutions,
Texas Instruments
Baher Haroun
Chief Technologist,
Wireless Business Unit,
Texas Instruments


Figure 1. Aggregate network backbone traffic for North America.
2 Texas Instruments
A combination of energy harvesting devices, more efficient power conversion and devices that consume less
energy will help meet the innovation challenges described above for emerging applications such as wireless
sensing, cloud computing and transportation.
Energy harvesting uses the available energy around us, including light, motion, vibration, radio frequency and
even body heat to power sensor systems. A number of offerings available today are converting low-level ambient
light into power for a variety of applications, such as light-powered wireless sensor networks that eliminate
costly battery replacement. In the near future, energy harvesting solutions may also enable wireless patient
monitoring by converting energy from body heat. Other applications, such as structural monitoring of bridges,
can be enabled by the combination of harvesting energy from vibrations and very low power wireless sensors.
Beyond the mobility of devices, the growing role of cloud computing for all global transactions is driving a
needed focus on energy efficiency and low power. If the Cloud represented a nation or country in and of itself,
as seen in Figure 2, in 2007 it would have ranked number five in total energy consumption3
. If we continue
business as usual, the Cloud is projected to move up in energy consumption rank within the next decade.
And what that means, of course, is that we need to sustain the Cloud growth without growing its energy
consumption. These energy efficiency improvements can come from many directions. Examples include
improving the power conversion efficiency, improving the processor and memory efficiency, reducing the power
loss in data transfer and developing more efficient software.


2007 electricity consumption. Billion kwH
Figure 2. The energy consumption rate of Cloud computing (if it were a country) was ranked number 5 in 2007 and is growing today,
underscoring the need for technology innovation to drive consumption down.
Driving innovation in energy efficiency and low power March 2012
Current and future
directions
Texas Instruments 3
Power conversion efficiency for the Cloud encompasses many aspects. High efficiency Point-of-Load (POL)
power supplies can regulate the voltage required by the processor needs. POL supplies improve efficiency by
two means. First, power can be distributed at a higher voltage to reduce board transmission losses. Second,
when processing requirement is low, the processor supply voltage can be reduced by the POL supply allowing
the processor to run more efficiently.
Processor and memory efficiency can be attained in many ways. One way is to build the processors and
memory in an advanced semiconductor process using lower voltages and smaller capacitances. However, the
largest power impact is usually achieved by using specialized processors architectures which are very efficient
at specific tasks, such as specialized video data compression and decompression cores.
Another area of power saving is to carefully change the supply voltage and speed of digital circuits to match the
task at hand and then completely shut down once the task is finished. This careful use of computation resources
reduces power consumed in standby due to leakage or unnecessary switching of logic gates.
Reducing power loss in data transfer is achieved by carefully choosing the methods for which bits are
encoded, signaling level and type of connections used and the physics of the transmission medium (copper
wire/transmission line, optical cable, or even a wireless link.)
More efficient software can reduce computation, storage and the amount of bits transmitted, improving the
system’s efficiency.
Texas Instruments has a long history of innovation in low power and energy efficiency, starting with a solar
powered calculator in the early 1980s, and a solution for a hearing aid customer that required a low power
digital signal processor (DSP) in the mid 1980s. The need to maximize operational time while proving greater
functionality and extended battery life has continued since that time.
Work in these areas was extended as TI began developing power-efficient solutions to serve the needs of cell
phone manufacturers. Today, TI is the leading provider of power management chips. To meet our customers’
needs and continually innovate to the next level of low power and energy efficiency, we take a systems approach
throughout the entire signal chain. This is required to best optimize low power and energy-efficient applications.
Driving innovation in energy efficiency and low power March 2012
Energy efficiency –
part of TI’s foundation
4 Texas Instruments
Examples of innovative approaches to energy efficiency abound in TI’s analog, embedded processing and
wireless products. The need for that innovation – the requirement that efficiency always be a top priority of every
product design and every product idea – is driven home across every area of the company, from product
development and design and the process technologies that serve as their foundation, to packaging and
manufacturing and software development (Figure 3). TI is also pioneering research in our labs, and through
collaboration with industry consortia, university research and development partners.
There are many ways to measure energy efficiency: power in versus power out, calculating the energy
necessary to quickly move one bit of information from one place to another, or determining the energy to
convert analog signals to digital information. TI engineers and designers continually evaluate product
performance versus energy consumed to optimize product efficiency.
Energy conversion is an important component of any solution. The ability to provide efficient energy
conversion solutions at various power levels is key. For example, converting energy from micro-power
sources requires nana-powered solutions so the harvested energy is not totally consumed by the conversion.
In other cases, efficient energy solutions are needed across a broad load range for applications that only
need full power during short periods of operation and can go from light load to full load in a short amount of
time. Lastly, many systems derive their electrical energy from high voltage sources like the AC line, so the
energy conversion needs to be able operate from high voltage while maintaining high efficiency.
System & Software:
– Essential to maximize
circuit level advances
Architecture & Packaging:
– Duty-cycle of CPUs
– 3D ICs
System Technology:
– Low-power optimized
Circuit Technology:
– Power management
System
&
Software
Architecture
& Packaging:
Silicon & Circuits
Figure 3. From circuit technology to systems and software, TI considers energy efficiency when developing semiconductor
solutions across its entire portfolio.
How it works
Driving innovation in energy efficiency and low power March 2012
Summary
The efficiency metric of determining the energy needed to move a single bit from one place to another is
important – whether the product is a sensor, a cell phone, or a server or the Cloud. This data path may be
wired or wireless. As you can imagine, the energy per bit is quite different depending on the transfer medium.
Parameters for this metric include the distance and bits per second. An increase in either of these parameters
will increase the energy requirements. The optimized solution will meet the goals of distance, bit-rate and
energy constraints while maintaining optimal error rate.
Another component in total system efficiency is digital computation efficiency. As the expectation of processing
and presenting greater amounts data evolve, the energy demands change. The goal is not to do less but do
more with less. Computations are required every time data are touched, from complex signal-processing
functions, to data searches, to image analysis or image compression. This is yet another area in which TI
products are prominent players.