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1124 results found, displaying items 341 - 360
Quad PoE Controller Handles Switches And Midspans
THREE EXTRA FEATURES previously unavailable in controllers for IEEE 802.3af Powerover-Ethernet (PoE) power-sourcing-equipment (PSE) make Maxim's MAX5945 unique. As the PoE specification requires, the quad controller provides discovery, classification, current limit, and dc and ac load disconnect detection to a powered device (PD). It also can operate autonomously or be controlled by software through an I2C-compatible interface. The novel features include...
Earning Market Share And Accolades
According to analysis from Bloomberg News, Prius sales in the U.S. more than doubled from 9918 cars in last year’s first quarter, and they continue to rise. Toyota expects Prius sales to almost double this year to 100,000 cars, up from 53,991 cars last year. And R.L. Polk & Co. says Toyota had a 64% market share of the U.S. hybrid car market, which consisted mostly of the Prius. Worldwide, well over 300,000 Prius cars have been sold...
My Test Drive Of The Toyota Prius
There's nothing like test driving the real thing. Toyota loaned me a practically brand new 2004 Prius for a couple of weeks and I proceeded to put the car through its paces (see the figure) . The results astonished even my skeptical self. Viewing the car from the outside makes it look like it provides little inside room. But this small and lightweight car (2890-lb curb weight) has plenty of legroom for the driver and passengers. It...
Setting The Standard For Hybrid Cars
With its sports-car look, avionics-like dashboard display, and an eerily silent and smooth start, it's no wonder that the Toyota Prius hybrid gasolineelectric vehicle is one of the fastest-selling cars of its type (Fig. 1) (see "Earning Market Share And Accolades," p. 44). Aside from these assets, though, it features one discriminating characteristic—it's a gas mizer. The U.S. Environmental Protection...
Non-Isolated DC-DC Converters
Sponsored by: NATIONAL SEMICONDUCTOR
What's the difference between isolated and non-isolated dc-dc converters? Isolation describes the electrical separation between the input and output of a dc-dc converter. An isolated dc-dc converter uses a transformer to eliminate the dc path between its input and output. In contrast, a non-isolated dc-dc converter has a dc path between its input and output. Non-isolated dc-dc converter designs usually employ ICs specifically intended for that purpose. ...
Multimedia H.264 Codec Trims Power For Portable Applications
The ability to add high-quality video capture and playback to portable systems just got easier with Mobilygen's MG1264. Consuming a mere 185 mW, this single-chip video codec can encode TV-quality VGA 30-frame/s H.264 video along with twochannel AAC audio. Systems ranging from digital TV broadcasting to next-generation handheld consumer systems are rapidly adopting the H.264AVC video standard, delivering MPEG-2 video quality at half the bit rate. The MG1264 comes in a 156-contact...
Power-Management Schemes Lower Leakage Currents
The SmartReflex adaptive power-management technology lets Texas Instruments' designers craft chips with lower active and standby power levels. Now in place with 90-nm products, it will be especially valuable in reducing idle current leakage as TI's DSP and other chips shift to 65-nm processes. SmartReflex combines intelligent and adaptive silicon, circuit design approaches, and software designed to solve power-and performance-management challenges at the smaller process nodes. TI...
PoE Networks
Sponsored by: POWER INTEGRATIONS
What is the basis for Power over Ethernet (PoE)? The IEEE 802.3af standard for PoE enables data terminal equipment (DTE) to receive power over the same cabling used for data in an Ethernet network. The standard specifies the protocol for delivery of a nominal 48 V dc over unshielded twisted-pair cables (such as CAT-5). This eliminates the need for a local power source. What does IEEE802.3af cover? The IEEE 802.3af standard presents...
Very Linear Power Amplifier Covers 2.4- And 5-GHz WLAN Bands
Today's portables need more power if they're going to take advantage of wireless local-area networks (WLANs). Developed by SST Communications, the dual-band SST13LP02 fits laptops, plug-in cards, and WLAN router/gateway/access points using 802.11a/b/g. This indium-gallium-phosphide heterojunction-bipolar-transistor power amplifier offers 20-dBm gain for 802.11b and 18 dBm for 802.11g in the 2.4-GHz band, as well as 18 dBm for 802.11a in the 5-GHz band. By covering the full 4.9- to 5.8-GHz...
Fresh Design Ideas Benefit AC-DC Supplies
Is it possible to say anything new about designing ac-dc supplies? Frank Rene, president of global product development at XP Power, sent along a list of five incremental enhancements that added up for his company. First, solder power semiconductors directly to the pc board and then bond them to the chassis, rather than insulating them and bolting them to the chassis. Countering the expense of thermal bonding materials, assembly costs go down. This also reduces size of the supply...
Voltage Reference Yields 1-mV Precision From 12-Bit ADCs
Speaking of new approaches to familiar products, bandgap voltage references have been around since the mid-1970s. Buried-zener references have been around since the early 1980s. Now Intersil has some new versions of its voltage references based on technology Xicor developed for depositing a precise charge on a floating gate. The most interesting is Intersil’s X60008-41, which provides a precise 4.096-V reference. It provides precise 1-mV resolution when used with a 12-bit...
Low-VIN Buck Regulator Toggles Fast-Switching/Very Low-Dropout Modes
The LTC3448 goes after applications in devices powered by single-cell lithium-ion, multicell alkaline, or nickel-metal-hydride batteries. Developed by Linear Technology, this 600-mA (continuous) buck regulator transitions from switch mode (at a constant 1.5 or 2.25 MHz) to a 160-mV very low-dropout (VLDO) mode when load current drops below 3 mA. Quiescent current is only 32 ?A in VLDO mode. Once the output current again rises beyond 11 mA, the switching mode toggles back on....
Built-In Magnetics In PoE Jack Assemblies Save Assembly Hassles
The 1658821 RJ45 Ethernet jack assemblies from Tyco Electronics integrate the isolation transformers necessary to inject power in Power over Ethernet (PoE) switches, including switches intended for Gigabit Ethernet. These modular, six-wide by two-high assemblies also include the jacks and heatsink as well as two bicolor LEDs per port. In fact, one 12-jack module replaces as many as 200 discrete parts. Press-fit assembly eliminates the need for wave soldering, facilitating lead-free...
Factorized Power Module Redefines The Wall-Wart
Previously, Vicor's Factorized Power Architecture (FPA) concept seemed constrained to a role as an alternative to the intermediate bus architecture (IBA). Now, the company's newest V°I Chip family member, the power factor module (PFM), takes the company from point-of-load to the ac wall plug (Fig. 1). With it, FPA promises significant reductions in ac-adapter size and increased ac-dc converter efficiency in converter configurations from...
Teardown Reveals Mac Mini's Cutting-Edge Design
With products like the iPod nano and the iMac, Apple Computer has demonstrated its talent for packing large amounts of functionality into small form factors. Yet its Mac mini desktop PC takes high integration to a whole new level. Creative design and cutting-edge components have produced a system that is small in size and cost but big on style and elegance...
Inductive-Boost DC-DC Converters
Sponsored by: NATIONAL SEMICONDUCTOR
What is an inductive-boost dc-dc converter? Closing the switch causes current to build up through the inductor, as shown in the simplified inductive-boost dc-dc converter circuit (Fig. 1). Opening the switch forces current through the diode to the output capacitor. Multiple switching cycles build the output capacitor voltage due to charge it stores from the inductor current. This results in an output...
Transmit-Path DACs For Portables Shrink Power Demand While Adding Features
The AD970x series of transmitpath digital-to-analog converters (DACs) for portables maintains compatibility with prior generations of Analog Devices' TxDAC series while reducing power dissipation and adding an on-chip voltage reference and RSET and RLOAD resistors. Clocking up to 175 Msamples/s, the series includes the 14-bit AD9707, the 12-bit AD9706, the 10-bit AD9705, and the 8-bit AD9704. Thin-scaled small-outline package (TSSOP) versions are pin-compatible with the previous...
Low-Noise LDO Regulator Provides Whisper-Quiet Voltage For RF Signal Chains
LOW-NOISE AMPLIFIERS, VOLTAGE-CONTROLLED OSCILLATORS, and other RF chips can take advantage of National Semiconductor's LP5900. This 100-mA, lowdropout (80 mV) linear regulator offers a 6.5-µV rms noise spec and a 75-dB power-supply rejection ratio. Its patentpending architecture achieves this performance without a bypass capacitor. All it needs is a 0.47-µF ceramic on the input and a 0.47- to 10-µF ceramic on the output. Standard output voltages are 1.5, 1.8, 2.0,...
Coupling Video Amplifiers
Sponsored by: INTERSIL
What’s the difference between ac coupling and dc coupling in video and high-speed amps? Using capacitors on inputs and outputs, ac coupling simplifies circuit design by removing dc voltages on the transmission line and isolating ground connections between the transmit and receive systems. On the other hand, the presence of those capacitors compromises signal quality. Some systems can accommodate those compromises, while others cannot. Eliminating...
Microgenerator Harvests Kinetic Energy For Wireless Devices
Wireless devices depend on batteries—at least for now. Soon, they will be able to draw power from their own kinetic energy. Perpetuum Ltd. and Innos have teamed up to develop a siliconembedded self-powered wireless device that feeds off of the vibrations in the environment to produce usable energy. Smaller than a matchbox, Perpetuum's electromecanical system comprises an arrangement of magnets on a vibrating beam. These magnets move past a coil, generating up to 4 mW....
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