Controlling Plug Loads through Their Embedded Electronics

Ben Eckermann and Ron Huff, Freescale Semiconductor

The makers of electronic devices face a daunting challenge: expectations for higher performance continue to increase with each new product generation while pressure for green solutions is also increasing. At the heart of this problem are the energy demands from embedded electronics that control more and more of what we plug in.

Although traditional offline powered equipment such as motors, lighting systems, and HVAC systems dominate electric equipment energy consumption, these loads have been the focus of efficiency efforts for decades.  During the time that the energy engineers have been working diligently to control those dominant systems, plug loads have exploded. More specifically, the embedded electronics that control our everyday online equipment such as printers, storage devices, networking infrastructure, and data processing are increasingly consuming a larger share of our energy resources. And now, even equipment and systems that were traditionally offline, such as TVs, refrigerators, and HVAC controls, are going online, which means they contain even more embedded processing.

To balance the performance required for powerful new electronic applications with rising concerns over energy consumption, efficiency programs, government regulations, and corporate sustainability initiatives are driving manufacturers to develop intelligent strategies for optimizing performance within specific energy budgets.

Traditional embedded computing platforms have been designed for maximum work load with little regard to the cyclical work profile across hourly, daily, weekly, or extended time intervals. However, new-generation high performance systems are shifting their design focus from provisioning worst-case maximum power loads to optimizing for energy efficiency across varying workloads.

Products such as printers are good examples of cyclical workload, as they tend to spend much more time in a ready-to-print state than they do for higher energy consumption printing states. Other embedded applications such as home network gateways, industrial processing equipment, and telecommunications systems have similar energy waste issues too.

As an example, office printers typically print cumulatively only 1 hour out of a 168 hour work week. Without system power management techniques, the 167 hours of idle time power cumulatively can exceed the active state power. Lowering power consumption requires advanced energy management schemes in the embedded electronics from product development engineers. Simple strategies to design lower power consuming electronics can begin to address the efficient embedded computing challenge, however, larger gains will come from creating flexible systems that can pace workload with energy consumption in an intelligent manner.

For the uninitiated in embedded electronics design, suffice it to say considerable effort is being made toward reducing the energy consumption of the many embedded devices in our homes – from TVs to printers, washer & dryers and refrigerators. (For the systems designers that might be reading this, an article written by these authors detailing very specific design approaches for embedded electronics can be found here at www.embedded.com.)

The fact that an ever increasing number of these “systems” are now networked to the external world undercuts many of these efforts. These devices spend the majority of their time idle, but all of us expect that they will remain present on the network, ready to answer to our latest whim in an instant from wherever we are and in response to whatever “app” we possess. This creates the need for a new energy conservation technique – minimizing power while network-connected and idle – but still ready to respond at a moment’s notice.

The goal is to achieve the best of both worlds – operating at ultra-low power the vast majority of the time, yet with no penalty of reduced functionality because the system can wake and respond as needed. Designers are challenged to continually increase product performance in embedded and networked applications for home and office while adhering to constantly shrinking energy budgets.

Within the cyclical states of these embedded networked applications, there are three techniques for low power network standby: packet classification, which saves power by allowing systems to parse and drop packets that do not need to be responded to; packet accumulation, which extends the time the system can remain in the network standby state by buffering packets for response at a later point in time; and, auto respond proxy which provides separate hardware to respond without waking the system.

Going forward, the increasingly stringent government regulations and public demand ultimately will require network standby to approach 0 W. The challenge will be to further innovate and reduce network standby power.