Exploring the options for distributed and point of load power in telecomm and network applications

Today´s networking and telecommunications power systems are more complex and demanding than ever before. Communications systems designers are faced with a number of voltage level requirements and a variety of products for creating DC to DC voltages. Feature sets such as power sequencing and frequency synchronization are required as complexity increases. Other requirements include sophisticated control methods, synchronous rectification, and better efficiency. As a result, designers have to wade through a sea of products that include these features and requirements. Increasingly, designers are relying more and more on the power management vendors to create total solutions. This paper provides methods employed by power management IC applications engineers for incorporating the available solutions from a topology standpoint and provides insight into design methodology for choosing a reliable solution. The solutions addressed are not particular to one company rather the majority of solutions are available from the top IC vendors. In addition, a new, proprietary technology is introduced. The new combi sync technology solves the problem of incorporating secondary side regulation and synchronous rectification into a single, all inclusive solution that is driven from a single transformer secondary as is a common, unregulated, rectified output. A second new technology to be introduced is a multiphase link controller for phasing multiple controllers thus reducing power supply noise. Subjects that are covered in this paper include secondary side regulation, control methods, interleaving of output phases, and general topology choice methods based on input and output voltages as well as required power. Additional subjects include hot swapping and power over Ethernet (PoE). The work is intended to provide insight on available solutions for seasoned power engineers as well as to explain power solutions to board level designers who don´t have a great deal of power electronics experience.