1124 results found, displaying items 181 - 200

The IEEE 802.3at Power over Ethernet Plus (PoE-Plus) task force anticipates the release of a "usable" draft standard in August, with a firm specification to follow a year later. PoE Plus will boost the maximum power delivered to applications to something around 60 W from the basic 802.3at PoE standard's 13 W at the application. Increasing the power was relatively simple, once the task force agreed that CAT5 cable and RJ45 connectors could handle more current (the approach...

Hi Bob: Your tip on how to phase a generator into the electric grid would work ("What's All This ‘Others Stay Lighted' Stuff, Anyhow?"). Phasing sets of the not too distant past used a couple of incandescent bulbs and a guy poised with his finger on the button, just as you said. I wanted to explain, however, that in the electric power industry, we go to great...

It's all about power nowadays as consumers snap up portable devices that require more and more juice. Designers are hard pressed to keep users' tanks topped up and to give those users an idea of how far they can go on what's left in those tanks. Maxim's latest solutions include a pair of power-management ICs as well as a programmable fuel gauge that can be built into battery packs. The MAX8662 and MAX8663 do more than integrate two synchronous buck regulators, a boost...

Internal charge pumps are fairly common in op amps, where they're used to achieve a "rail to rail" output swing. Now, they're being used in other amplifier applications to provide output swings well beyond the range of the supply voltage as well as to solve some challenging design problems. Maxim Integrated Products now offers a pair of video amps and an audio power amp that illustrate this trend. The MAX9509/9510 video amps operate on 1.8 V yet deliver the 2-V p-p...

More point-of-load (POL) dc-dc converter modules with internal inductors and FETs are hitting the market. The idea is to make designing with switching regulators no more challenging than using old-fashioned three-terminal linear regulators. Linear Technology's LTM4601, LTM4602, and LTM4603 include inductor, power MOSFETs, dc-dc controller, compensation circuitry, and I/O bypass capacitors and have current ratings from 6 to 12 A. Each device comes in a 15- by 15- by 8-mm...

If you have direct methanol fuel cells (DMFCs) in mind for your projects, check out an article in the IEEE Power Electronic Society's latest newsletter. "Electrical Dynamic Behavior of a Direct Methanol Fuel Cell" by M. Ordonez and others of the Memorial University of Newfoundland reports on a series of empirical evaluations carried out on a standard experimental DMFC from Fuel Cell Technologies and relates their test results to a theoretical fuel-cell equivalent circuit. The good...

If you're designing mid- to low-volume systems with a buck converter in the power chain, you may have used one of National Semiconductor's Simple Switcher voltage-regulator chips, which now offer a couple of new wrinkles. An enhancement in the Webench design environment already makes using these switchers "simple." Meanwhile, a novel technique reduces noise susceptibility in current-mode feedback. Webench online design tools span a range of National products. For Simple...

Designing power-management subsystems, which supply and control dc power in electronic systems, is much more complicated now than it was five years ago. These days, designers must cope with ICs that operate below 1 V, may consume over 100 A, and employ gigahertz clock rates. In addition, such subsystems involve more than just power-supply design. They also include system-oriented functions that require application-specific ICs. A system viewpoint is necessary to set the...

When the days were old and the knights were bold and IP was invented, you'd wrap an insulator around your gate and leakage was prevented. As the insulator became thinner with process shrinkages, though, leakage became a problem. It's so bad, engineers are now having nightmares about their future 45- and 32-nm designs. "Subthreshold and gate leakage have become a large problems in deep-submicron technologies," says Dan Hillman, vice president of engineering at...

Suppose you're designing a really low-power telemetry application— so low-power that you want to run it off free energy that you "harvest" from the environment. Let's say it's intended to monitor the vibration signatures of the wheel trucks in railroad boxcars and send data about those signatures to trackside collection points via a wireless link. Suppose further that you want to power the application from those same vibrations. Advanced Linear Devices' ALD...

Here's an off-the-shelf series of wall-warts (small, self-contained, plug-in dc supplies for portable equipment) that not only meets worldwide energy conservation standards but also comes with its own assortment of twist-off power plugs. Advanced Power Solutions' 2K6S series delivers 6 to 12 W from 0- to 264-V 50- or 60-Hz ac inputs (...

There are two conflicting ways to increase power-distribution efficiency in data centers as electricity flows between the front-end voltage converter and the ICs on blade servers. One is to lower the bus voltages around the circuit board. The other is to raise them. There are compelling reasons to think that the latter approach is better—if it's done right. For high-end IT and telecom applications, traditional power conversion involves an ac to 12-V dc silver box...

Besieged by conservation issues, utility metering is undergoing somewhat of a renaissance—particularly electricity metering. That's because electrical distribution systems everywhere are fragile. Metering used to be the nearly exclusive domain of EEs with a power specialty. Today, it's wide open to chip, board, and system designers, as well as software writers. The reluctance-motor electrical-meter movement is more than 100 years old. Now, it's getting displaced...

Advanced power-reduction techniques, such as multi-VDD architectures and power-aware clock tree synthesis (CTS), allow designers to implement large, complex SoCs that consume less power. Leakage power can be minimized by using multi-threshold libraries and by shutting off blocks based on the mode of operation. Dynamic power can also be reduced using different blocks operating at varying voltages. Significant power savings can be achieved through power-aware CTS techniques, such as...

As the semiconductor industry traverses through the deep-submicron process nodes, each plateau along the way carries its own signature bugaboo arising from physical effects. At 180 nm, timing-closure issues got everyone's attention. At 130 nm, signal integrity was the topic of the day. At 90 and 65 nm, though, power integrity and leakage are weighing on designers' minds. We now pack so many active elements onto such a small slab of silicon that power density has reached...

What is a Class D amplifier? A Class D amplifier converts an audio signal to pulse-width modulation (PWM). Its power stage efficiently amplifies the PWM signal and filters it to drive the speakers. The Class D designation means that the power stage biases and operates its output devices as switches. How do half-bridge and full-bridge Class D amplifiers differ? A half-bridge power stage uses a pair of switches in a totem-pole arrangement (...

The ASM Global Performance series of ultra-miniature open-frame switching power supplies features 10 versions with single outputs of 3.3 to 24 V dc and a power range of 10 to 15 W (see the figure). All of the models accept inputs of 90 to 264 V ac. The supplies, which incorporate corner...

The box of Christmas lights said "If one or more lights go out, others stay lighted." Yeah, sure. My wife bought several cheap boxes of 100-light strings, and they looked very nice. This year, she had great plans to drape them along a fence, which would look real pretty. But some of the strings were dead—kind of frustrating when you want to put the lights up now. I did some simple checks. If one bulb went open, the others in series went out. Yeah, 5-V...

Based on the exhibits at this winter's auto shows, cars powered by next-generation technologies aren't too far away. At January's 2007 Auto Show in Washington, D.C., Ford rolled out a version of its Edge crossover vehicle that combines a lithium-ion (Li-ion) battery pack, a hydrogen fuel cell, and plug-in technology for fuel efficiency that exceeds 41 mpg with zero emissions—except for water vapor (...

Most large-scale chips for wireless, communications, and networking contain at least one embedded core for control or signal processing or both. As processing speeds have increased to keep up with the demand for the latest standards, protocols, and applications, these embedded processors have had to kick up their processor speeds. But this translates into increases in power consumption that can compromise or even become a knockout factor for a battery-powered device....

• Build A Smart Battery Charger Using A Single-Transistor Circuit
• Efficient DC-To-AC Inverters Charge Equipment Racks
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• Easy-To-Build AC Power Meter
• Voltage-To-Current Converter Works From A Single-Supply Rail