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Take Simple Steps Toward Extreme Low-Power Design
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...
Li-ion Suppliers Try To Find The Right Chemistry With Car Buyers
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...
Non-Isolated Point-Of-Load Regulator Modules
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: ...
A Bright Future For LED Illumination
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...
White LEDs Promise Green Illumination Domination
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. ...
Select The Right Ultracapacitor Solution
Like all capacitors, ultracapacitors have a high power density. Yet unlike their traditional counterparts, electrolytic capacitors, ultracapacitors offer high energy density, allowing them to store a vast amount of energy in a small package. The capacitors that most design engineers are familiar with have very short time constants, which means their voltage cycles quickly. Ultracapacitor arrays, though, have time constants on the order of tens of seconds to...
Tree-To-Earth pH Difference May Generate Harvestable Energy
An experimental wireless mesh network for monitoring forests for fire danger was recently demonstrated while being powered by the trees themselves during the Global Semiconductor Alliance Emerging Opportunities Expo & Conference, held earlier this month in Santa Clara, Calif. The demonstration used energy-harvesting hardware developed by a Massachusetts company called Voltree Power. The test took place at the National Interagency Fire Center...
Powerline Carrier Modem Chip Facilitates Design Beyond Remote-Reading Meters
On Semiconductor’s AMIS- 49587 powerline carrier (PLC) modem does more than remotely read smart electric automatic meters. It invites a closer look at street lighting control, smart power plugs, building automation, and other applications that are part of the Smart Grid, which is a potentially disruptive technology that may offer new opportunities for design engineers (see “...
Fixed DC-DC Regulator Output Uses A Digitally Controlled Potentiometer
Digitally controlled potentiometers (DCPs) have become very popular in a wide variety of applications, including control, parameter adjustment, and signal processing. The digital pots replace mechanical potentiometers and provide advantages such as remote operation and programmability, higher resolution, a much smaller form factor, increased reliability, the ability to store multiple wiper positions, and lower total system cost. A...
Save Power By Managing Unused CMOS I/O Pins
It’s easy to overlook unused digital inputs when designing with a CMOS device, but doing so invites problems. When unused digital inputs are left unconnected they will float, which can cause both unexpected logic behavior and excessive current draw. Several simple approaches for managing these unused inputs can save significant debugging grief. Essentially, a CMOS digital input circuit uses MOSFET transistors in pairs (...
Regenerative Current Transformation Delivers Sub-Volt Regulated Output
Regenerative topologies and systems have been explored extensively in regards to providing regenerative loads for burn-in systems,1 enabling efficient burn-in of power supplies. Regenerative burnin systems are desirable, as the power supply ideally functions as both source and load. This means a substantial energy savings (up to 90%) when attempting to provide a burn-in function. For example, in a non-regenerative burn-in...
Engineering Students Take Home A Prize For Their Design Idea
WELCOME TO THE SECOND annual Ideas for Design issue, celebrating one of our most popular departments. This issue includes additional IFDs, written by readers like you, and feature stories by staff and industry contributors alike. All of these authors got their start as engineering students, learning how to put together their first designs. Today, students still have to complete senior projects as part of their initiation into the real world of...
Reap The Benefits Of Integrated Power-Limiting Controller ICs
Many cost and engineering improvements are realized by integrating the current pass element and currentsense function into a hot-plug controller integrated circuit (IC). Controlling the passelement power is the safest and fastest way to charge the load capacitance. Pass-element protection is maintained while boosting efficiency and reliability. A circuit controlling current to a load usually consists of three components—an IC...
Transformer-Isolated RS-485/422 MEMS Transceivers Integrate DC-DC Converters, Terminations
There are other RS-485/422 transceivers with inductive isolation available, but Linear Technology has taken a step forward. Its LTM2881 µModule includes its own complete, isolated dc-dc power supply, including the transformer, eliminating the need for any external components. The integrated power supply powers the transceiver and provides an isolated 5-V supply output for powering any supporting external components. (ADI’s ADM2485 has an on-chip...
The Five Building Blocks Of An Efficient, High-Brightness LED Driver
As high-brightness LEDs (HBLEDs) penetrate all avenues of the lighting market, various semiconductor manufacturers are offering constant-current drivers. Only by choosing a driver IC capable of meeting the flexibility and control required by today’s applications can the true potential of HBLEDs be unleashed. Theatrical lighting, for example, often requires high dimming resolution while dynamically adjusting the current to account for fluctuating power...
A Word About RF Power Transistors
MOSFETs used in cellular and other PAs are virtually 100% discrete RF power transistors. The laterally diffused metal-on-silicon (LDMOS) FETs are the most popular type. Freescale Semiconductor is a leader here, with a wide range of devices. The company’s recent products include the MRF8S9100H/HS, which operates in the 920- to 960-MHz range. It’s designed for class AB or C operations in GSM/EDGE systems. It can deliver 45-W average power, a gain of 19.1 dB, and an...
Thinking In dBm
When you think of power, you think of watts. It’s a different story with RF PAs, though. Not only is the gain of the amplifier given in dB, but the power output also is normally quoted in dBm. Get used to it. Just as a reminder, the gain is computed with the familiar formula: dB = 10 log (Po/Pi) Power output is computed with a 1-mW reference: dBm = 10 log (Po/0.001) Po = 0.001...
Key Power-Amplifier Specifications
Adjacent-channel power ratio (ACPR): The ratio of the integrated signal interference power in an adjacent channel to the integrated power in the desired channel Error vector magnitude (EVM): A measure of the distortion in the I-Q constellation diagram of a signal due to phase or amplitude differences; it’s the length of the error vector drawn from the ends of the vector to the desired...
Leading-Edge Products Help Designers Put A Stopper In The Power Amp's Power Drain
Transmitter power amplifiers (PAs) consume more power than any other circuit in today’s wireless applications. In some cases, PAs swallow up more than 50% of the power budget. Also, their inefficiency produces excessive wasted power as heat. With cellular basestations joining the green trend and cell phones including ever more features and multiple radios that shorten battery life, the industry is turning its attention to the PA. One main factor causes the PA’s...
Cool Ceramics Help Simplify LED Heat Dissipation
Light-emitting diodes (LEDs) suffer from heat problems that understandably can limit their success as a light source. Much attention is given to the heatsink, and less is given to the layers and barriers between the LED and the heat-dissipating surface. A change of concept and material allows for significant gains in thermal management and reliability in addition to a simplified system. Using ceramics as a heatsink, circuit carrier, and part of...
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