Electric double-layer capacitors (EDLCs), better known as ultracapacitors or supercapacitors, are now a primary energy storage option for design engineers. During the past 10 years, we have seen the emergence of this technology, especially with the move toward “green” and more energy-efficient options. These devices have an advantage over batteries, particularly in applications requiring long life or operation in low temperatures.

Philips Electronics is the first company to submit a prototype LED replacement for the common 60-W bulb in the U.S. Department of Energy’s $10 million Bright Tomorrow Lighting Contest. However, Congress has yet to appropriate funding for the prize, and questions remain about contest eligibility.

Designers parallel their power supplies to increase system power output or to provide fault tolerance. Paralleling also improves system performance. When both power supplies are load sharing, for example, the two supplies share the dissipated heat, improving reliability. Furthermore, if one power supply goes offline, the other one is coming from an already loaded state, so the perturbation on the output is not significant.

The battery industry is being lauded as the great hope for domestic manufacturing and job creation. Much of the economic stimulus package has been directed toward the fabrication and recycling of lithium-ion (Li-ion) batteries in the United States. The $790 billion economic stimulus legislation includes tens of billions of dollars in loans, grants, and tax incentives for advanced battery research and manufacturing.

Practicing engineers are always learning and perfecting their craft. With the demand for more portable, battery-powered devices and energy harvesting on the horizon, the requirements for even lower-power designs have gotten more challenging. At first, designers wrestled with saving milliamps, then microamps. Today, it is all about saving nanoamps. As a result, designers have to elevate their thinking to another level. Extreme low-power embedded design...

Since Sony introduced them in 1991, lithium-ion (Li-ion) batteries have transformed portable electronic products. Now, carmakers and would-be automotive battery suppliers are looking for a similar transformation to redefine automotive propulsion. Currently, well over 2 billion Li-ion battery cells are sold annually for consumer electronic applications, most notably cell phones and laptop computers. If cars become a significant market for Li-ion batteries, this...

Analog & Power Editor Don Tuite answers some frequently asked questions about non-isolated point-of-load regulator modules, including: What is the Intermediate Bus Architecture? Functionally, what does a POL regulator comprise? How do newer packages deal with the switching inductor? Are there disadvantages to an integrated inductor? And more! Fill out this brief form to download the FAQ: ...

Nearly all market forecasts paint a positive picture on LEDs being used for general illumination. Market research firm Databeans Inc. expects the market for LED lighting applications, including white LEDs, to grow an average of 23% over the next several years. Worldwide sales this year alone will total $500 million, and LED revenues will hit $1.8 billion by 2013 (see the figure). The vast majority of such sales will be for...

The lighting is on the wall: Solid state is threatening to dismantle the dominion of incandescent and compact fluorescent light (CFL) sources. Illumination applications based on solid-state lighting are slowly replacing those previously ruled by the older technologies. Though very expensive to use, solid-state lighting has proven more efficient and in sync in a world where government initiatives are calling for a greener environment and less energy consumption. ...

The IEEE recently presented a panel discussion with some of its most esteemed fellows and members to celebrate its 125th anniversary. Panelists included Miguel Nicolelis of the Duke University Medical Center, Katie Hall of WiTricity, Rangachar Kasturi of the University of South Florida, K.J. Ray Liu of the University of Maryland, Dharmendra Modha of IBM's Almaden Research Center Krishna Palem of Rice University, and Roy Want of Intel.

After the Roadster test drive, I had a serendipitous interview with Tesla’s CTO, J.B. Straubel, during MIT’s annual Emerging Technology conference. In the video interview, Straubel shares info about the upcoming Tesla sedan and the new factory slated to be built in San Jose.

Getting to take a test ride in a Tesla Roadster is a thrill enough, but getting Bob Pease out for a spin as well—talk about an experience! Our Analog and Power Editor Don Tuite just so happens to married to Vicky Tuite, senior test engineer at Tesla Motors. Talk about lucky. She recently had the keys to a brilliant orange Tesla with the enviable mission of running down the batteries for some low-charge tests the next day. And guess who got to ride shotgun.

A maximum power point tracking (MPPT) controller circuit is extremely useful in solar photovoltaic systems for boosting power usage efficiency. The traditional MPPT design, though, requires the use of a multiplier to calculate power from source voltage and current measurements. However, it’s possible to build an MPPT controller without this multiplication stage by measuring power on the load rather than using source parameters. If we aren’t in the presence of a...

The standard practice for calculating the ripple voltage of a simple rectifier circuit with a reservoir capacitor (Fig. 1) is to linearize the problem. A linear approximation of the voltage across the reservoir capacitor (Fig. 2) assumes that the discharge time is equal to the period of the input sine wave, which is only approximately true for...

A high-side current-sense amplifier typically amplifies the differential voltage across a sense resistor and provides an output voltage proportional to the current in that resistor. The amplifier rejects the common-mode voltage on which the sense-voltage rides. Such devices, therefore, can be used to detect overcurrent faults in a load or to make system power-management tradeoffs. Most high-side current-sense amplifiers are well suited for situations in which...

By adding only a few components, you can turn a temperature- and beta-compensated current sink into a common-emitter (CE) amplifier that maintains a stable biased operating point. This architecture is useful for building stable and device-tolerant BJT Class A amplifiers. The circuit in Figure 1 sinks a constant current (ICE3) through Q3’s collector and emitter. This design is balanced so changes in Q3’s...

At times, designers face a limited amount of wire and/or a limited cost to communicate with a remote device such as a sensor. Many devices allow communication over an ac or dc power line employing an AM or FM modulation scheme. However, they tend to be costly. This design is a simple, low-cost method for sending data across the same wire used to supply power. It’s based on modulating current from a remote device back to a host. A later example...