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Trend Report: Energy Conservation and Sustainable Design

Mon, 08/25/2008 - 7:56am
For a US company intending to launch a worldwide product, compliance with EuP regulations will ensure entry to that market of almost 500 million people.
Jeff Uden, Newark

One of the most interesting trends in the electronics industry at the moment is the movement towards designing products in an environmentally friendly way. Buzzwords such as Carbon Neutral, Sustainable Design and Eco-design have recently entered the vocabulary of designers and in the near future, energy efficiency may become just as important as performance and cost are now.

The concept of sustainable design started, not as a way of conserving the environment, but to prolong battery life in portable consumer goods, such as cell phones, laptops and PDAs. Many of the concepts developed for these devices have now passed into mainstream applications, including advanced power management and LED backlighting.

There are many reasons that these concepts have moved into the design of mainstream products, but perhaps the most important one is the onset of environmental legislation in an increasingly global marketplace. ?In the absence of Federal legislation in the US or Canada, a patchwork of local regulations has sprung up concerning recycling, product restrictions and marking. For example, most states and Canadian provinces are now either planning or already have legislation that requires recycling of certain types of electrical equipment at end-of-life. And most states have either banned or are planning to ban landfill disposal of televisions, computers and monitors. These are burdensome, as there is little consistency in the regulations.

Adding to the complexity is the current trend to design one product for the global market, which means designers must be cognizant of directives such as the European Union’s RoHS, New Batteries, EuP and REACH.

Like the regulations currently in operation in the US, RoHS, Reach and the New Batteries directive concern the banning of harmful substances, and the disposal of equipment at end of life, but EuP takes a look at designs themselves, and gives guidance on how to ensure they are as efficient as possible. EuP is intended to ensure that compliant products can be sold throughout the entire EU region. For a US company intending to launch a worldwide product, compliance with EuP regulations will ensure entry to that market of almost 500 million people.

To investigate the scope of the EuP regulation is beyond the scope of this article, but since the focus of EuP is efficient design, then the easiest way to begin compliance is to build a device which is as efficient as possible. (For detailed information about global regulations, you can visit the legislation center at www.newark.com/edworld). Even if the product to be designed is not intended to be for global consumption, an efficient design can be an excellent selling point, giving rise to claims that it will pay for itself in energy saved over a relatively short percentage of the product’s usable lifetime.

The power chain is the logical place to begin this optimization process, as powering the circuit’s boards and components incorrectly will exacerbate any inefficiency inherent in the design, and conversely, a good power chain design will ensure that a good design works as efficiently as possible.
Power Chain
Whether a device is powered from the mains or a battery, voltage has to be converted at least once, and usually more often, to be able to

click to enlarge

Power Chain Design
Designing a product to be as efficient as possible will soon become the norm. The power chain is the logical place to begin this optimization process. The first step in producing an efficent power chain design is to get a top level view of the entire system. Designing the power chain to be as efficeint as possible will provide other benefits apart from using less energy.
supply circuits with the correct input voltages. Designing the power chain to be as efficient as possible will provide other benefits apart from using less energy. Wasted energy is given out as heat, so an efficient design will generate less heat, therefore it can negate the need for thermal management equipment, reducing the cost of components. Components working within normal operating temperatures will also be more efficient and have a longer lifetime.
System Level Design for Maximum Efficiency
The first step in producing an efficient power chain design is to get a top level view of the entire system, because although the standalone efficiency of the power supply, conversion or regulation elements of a product are very important, it is also critical to minimize losses and maximize the efficiency of the overall product. Different system architectures can have a significant bearing on overall energy efficiency, so it is important to make the right choices early in the design cycle. Early collaboration, either directly with the power product manufacturers or with distributors able to provide technical guidance, can help ensure the best power management choices are made. This approach can often mean that standard products rather than more expensive, often less efficient, custom or modified-standard modules may be specified.
Module Efficiency
Manufacturers offer ranges of modules designed to complement each other, and can provide a quick and easy way to implement an efficient power supply design. To implement a modular solution, the designer must be prepared to compromise a little on cost, board space and flexibility. But modules can provide an especially good solution for low to medium production quantities. Companies such as XP Power, Lambda and Murata Power Solutions to name a few, are utilizing the latest semiconductor technologies, plus a host of other innovative features and processes in their latest power modules.

Examples of these features include: multi-layer heavy copper PCBs, synchronous rectifier topologies and planar magnetics. These all lead to increased efficiency and higher power density and support feature-laden products housed in small footprint packages.

There is a strong link between small form factor design and higher efficiencies. However, without careful design, modules with high component densities can be more prone to thermal issues. This potential problem needs to be managed carefully so that the good work done improving efficiency and power consumption at module level is not undone by a necessity to consider additional thermal management.
Components
For higher production quantities, a custom power chain design using discrete components can offer the maximum efficiency, lowest cost and smallest board real estate. Some of the biggest developers of power chain components such as National Semiconductor, Texas Instruments, Freescale, Maxim, Linear Technologies, International Rectifier and Analog Devices continually vie to have the lowest power and most efficient products for a range of end markets. There have been strong technical advances in the power electronics sector in recent years that have helped yield specification improvements including higher efficiency.

As well as increasing efficiency, advances have been made in miniaturization, integration and mixing technologies. Many, if not all of the companies mentioned above have integrated both analog and digital logic on the same die. National Semiconductor’s Adaptive Voltage Scaling and Freescale’s SMARTMOS technologies are two examples of this methodology. The mixed technology adds intelligence to the component and allows extra features to be incorporated on the same die.

To give specific product examples of some of the size and features that can be found in modules, take a look at some DC/DC converters on the market. DC/DC converters are designed to sit between the AC/DC supply and the circuit board to provide a supply which is closer to the point of load, lowering losses and providing higher efficiency at least in the low 70% range.

XP Power’s JCA range of miniature, board-mounted low power DC/DC converters measures just 1” x 0.8” x 0.4”, allowing designers to reduce the size of new developments or add in more features, while maintaining the industry standard pin-out. The JCA range has 2, 3, 4 and 6 W models, each offering a choice of 4 input voltages of 5, 12, 24 and 48 VDC. For each input voltage, single output models offer +3.3, +5, +12 or +15 VDC outputs or the dual output versions provide +/- 5, +/- 12 or +/-15 VDC. Outputs are fully regulated, varying no more than +/- 0.3% over all input conditions, and less than +/- 1.0% across all load conditions.

The example above is for a general solution, but DC/DC converters can often offer more efficiency when targeted at a specific end market, because of its ability to offer higher integration and focused features. For example, Analog Devices’ ADP1829 switching regulator offers a solution for the industrial, telecoms and networking industries. The ADP1829 is a dual, interleaved, synchronous PWM buck controller, which provides high-efficiency DC/DC power conversion and generates two independent output rails, as low as 0.6 V, from an input of 3 to 20 V. The two channels operate 180° out of phase, reducing stress on the input capacitor and allowing smaller, low cost components.
Summary
Designing a product to be as efficient as possible will soon become the norm, rather than the exception. The best place to begin is the power chain, as a bad power chain solution will negate any savings made by an efficient design, and a good solution will make the best of even an averagely designed circuit. The switchover to a high efficiency power chain may be not as difficult, and will definitely not be as expensive as may be expected. In fact, with the savings on your bills of material to requiring less thermal management products, the cost differential may even work in your favor.

Jeff Uden is director of Semiconductors, Passives, Optoelectronics for Newark, 800-463-9275, www.newark.com.

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