Power consumption and power dissipation are really two different things. Power consumption is the intended use of power; work is performed. Power dissipation is a function of efficiency. Both, however, are highly dependent on operating temperature, the semiconductor process that is used to make the device, operating frequency, level of activity, and operating voltage. Both can be reduced through intelligent design...
Considering that battery life is a huge factor in the mobile phone market (or any other portable device, for that matter), it is common sense that devices that use less power will extend battery life until the next charge. Intelligent design, coupled with chips that perform actions while consuming mere micro-amps (µA), can create a stellar device with a full complement of impressive and even life-changing features for the consumer.
Just ten years ago the amount of power that makes up an entire power budget today would have been a negligible loss back then and of no concern. These days, design for power efficiency is much more aggressive.
How do you reduce power consumption so radically? Common sense says to turn off the lights when you leave a room but ultra low power takes it a step further by "dimming the lights" whenever possible. A large portion of power savings comes from turning off unused portions of a circuit, or putting entire sections in sleep mode until needed.
But once that trick is used, what then? This is the world of ultra low power, the next evolutionary power savings for electronics. Apply shutdown and sleep modes to everything in the circuit. Design like power is a precious commodity and examine the relationship of power and potential (P=VI) with every voltage step up/down, examine impedances (P=I2R), and note that every heat source is evaporating power like steam in a boiling pot, since energy cannot be created or lost. Energy will go somewhere, so it might as well do work while it gets there. Size your components appropriately, since a resistor whose wattage is too small for the application will burn off the excess current as heat.
High frequency design in general is a real game-changer. Ultra low power design accommodates the change with knowledge of a few laws of physics. The higher the frequency (i.e., the higher the clock rate), the more energy is consumed when capacitance is present. So power savings in layout can matter, since parasitic capacitance (formed when conductors are near each other but not electrically connected) counts. Parasitic capacitance used to be ignored as a negligible consequence of design choices, but now has become a challenge that must be dealt with.
Ultra low power design is not for the lackadaisical or faint of heart. Advances will continue to be made, but you can be sure that some factors that we don't consider now will become design trade-offs later as our component suppliers continue to innovate to ever greater lows.
Mouser Electronics
These articles were featured during the Ultra-low Power System Design Workshop at Embedded World 2013 in Munich Germany on February 27, 2013.
Contributed by Energy Micro
When a battery needs to support a product during many years or even decades of operation, incremental improvements in MCU integration and minor tweaks to basic processor architecture are insufficient to achieve the dramatic hikes in energy efficiency that are required.
When it comes to putting devices in hard to reach places, power consumption plays a major role. The device needs to either operate independently for a very long period of time or needs to be sufficiently small so as to not be intrusive, which requires very low power usage.
Contributed by TI
A few years ago, micro-harvesting could have been called a scientific curiosity. But the design community's long march to ultra-low-power (ULP) technology has had the unexpected result of pushing micro-scale energy harvesting out of the lab and onto the designer's bench.
Contributed by Silicon Labs
The myriad benefits of improving energy efficiency have been well-documented: lower electric bills for consumers, reduced load on utilities, reduced cost of ownership for electronics products and fewer spent batteries thrown away in landfills.
