Electronic Design

Power> Management And Semiconductors

The Quest For Higher Density And Faster Access

The word "simplify" might just be the battle cry for current-generation power-management ICs. So many of today's components are crafted with the intention of making it easier to perform power conversion, distribution, protection, or control.

A well-defined application that justifies the development of application-specific standard products with multiple power functions integrated on-chip often makes this possible. Applications such as isolated dc-dc converter "bricks," Power over Ethernet, microprocessor power supplies, and cellular phones are just a few examples.

In these systems, highly integrated power-management chips are simplifying the power-management tasks for system designers, saving development time, board space, and cost versus existing solutions. In most cases, power-management ICs also are addressing power-specific performance concerns like efficiency, power dissipation, voltage regulation, and transient response.

In portable applications, power-chip developers are helping system designers squeeze the last coulomb of charge from their batteries. Meanwhile, for fixed applications, power-IC developers are finding ways to deliver the most amps to the loads at very low voltages while dissipating the least amount of heat.

Copackaging aside, parasitics are now becoming a concern in the development of some single-chip DACs. As converter speeds approach the gigasample-per-second range, the parasitics associated with the leadframes and bond wires in traditional IC packages begin to limit DAC performance. Fortunately, the use of flip-chip assembly and BGA-style packages can greatly reduce package parasitics and allow the DAC to perform up to the limitations of the silicon. Even more important, however, may be the chip developer's understanding of application requirements and the impact that tradeoffs at the system level have on the performance of power-management components.

TOP TEN

  • CHIP-SET OPTIONS for building isolated dc-dc converters will expand further. Power-supply controllers now offer chip-set solutions for building isolated dc-dc converters. Some system designers will opt to use these chips or chip sets to embed the power supply in their designs, rather than use purchased bricks. Or, they may employ bus-converter chip sets to build isolated converters for intermediate voltage bus architectures.
  • BUILDING AN ISOLATED dc-dc converter, either as an embedded converter or as a brick, is becoming easier as new controllers arrive with high-voltage and multiphase control capabilities. For example, National Semiconductor has introduced a forward converter with active clamp (LM5025). This part, with its 14- to 100-V supply range, will be a building block for the newer wide-input (4:1 input range) bricks and embedded converters. The chip is one of several new parts built in a high-voltage process that allows for a startup regulator to be pulled on-chip with the controller.
  • THE HOT-SWAP FUNCTION has long been separate from the dc-dc converter. That should change, though, as brick manufacturers begin to add hot-swap capability to their products.
  • EXPECT TO SEE A HOST OF PoE power managers offering varied approaches to the implementation of operations required by IEEE802.3af and legacy PoE systems. Some newer controllers will exploit smart partitioning of power-management and physical-layer functions within chip-set solutions crafted for power-sourcing equipment (PSE) and powered devices (PDs). On the PSE side, there are also plans to integrate the controller into the RJ-45 jack, creating a PoE-savvy connector. Furthermore, it's expected that PD-side power-management functions will be integrated with the needed dc-dc converter functions.
  • DIGITAL MULTIPHASE POWER CONTROLLERS will be cost-competitive with analog multiphase controllers, enabling more applications to benefit from their flexibility. This applies in particular to server applications. One innovation will be a controller with dual control loops that will let one chip replace two chips, thus generating two output voltages.
  • PORTABLE CONSUMER APPLICATIONS, such as cell-phone handsets, PDAs, and notebook computers, continue to spur creative solutions for managing power. Cell phones alone offer a variety of power-management functions, including battery charging and fuel gauging, dc-dc conversion for baseband and RF functions, supply monitoring, bias control for the RF power amplifier, and an LED drive for backlights. Some semiconductor vendors will integrate these functions to reduce design footprint, while others will separate them to give phone makers greater flexibility.
  • LIGHTING MANAGEMENT may emerge this year as its own market segment within power management. In 2003, white LED drivers proliferated as manufacturers of power-management chips sought to satisfy the growing demand associated with the widespread use of LED backlights in color LCD displays. Last year, another white LED application appeared, the electronic flash used by digital still cameras in cell phones. The white LED flash may consist of four or five LEDs in series and need to be driven with a 100-mA pulse of drive current at a voltage equal to the sum of the LEDs' forward-voltage drops. The flash application is likely to be just one of many applications that should extend LED usage beyond backlighting. In the coming year, semiconductor vendors will exploit their high-voltage process capabilities to develop LED drivers for flash and other emerging applications in solid-state lighting.
  • MOTION-CONTROL CHIP SETS NOW PROVIDE highly integrated designs for servo applications. Some of the most recently developed components will relieve system designers of the programming burden associated with developing motion-control algorithms. Digital controllers, such as International Rectifier's IRMCK201 and IRMCK203, reduce control algorithm programming to a series of menu selections.
  • ENERGY-METERING ICs make it possible to develop electronic energy meters with sophisticated features for energy measurement, power-quality monitoring, and theft protection. These components are evolving by implementing lower-cost, more integrated energy-metering designs. They're also enabling high-end power meters with greater energy measurement accuracy, LCD displays, serial communications, and other features.
  • ONLINE DESIGN TOOLS will continue to simplify the design of dc-dc converters, both isolated and nonisolated.
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