Analysis and design of a digitally controlled current source based multi-output converter

In recent years the trend to lower voltages at higher currents has gained interest. Unlike earlier processors that operated from a single voltage level, a typical modern digital power architecture now has multiple voltage levels to support various logic families. With the advancement of the relatively newer Intermediate Bus Architecture (IBA), interest in point-of-load converters has increased. To support multiple output voltage levels from a single input voltage level, a power distribution system having a central power supply that acts as a controlled current source is analysed. Unlike the prevalent multiple output converters where different output voltage levels are determined by transformer turns ratios, here output levels are determined by share of input current for each individual output. All the magnetic components are concentrated in the front end converter acting as the current source resulting in reduced magnetic count. The current source is realized by a output current controlled buck converter.; This topology can also be extended to the idea of simultaneous charging of multiple batteries at different voltage levels. With the growing interest in Lithium-ion/polymer cells, the research work is concentrated to lithium charger application. The charger is modified to accommodate "Pulse charging" technique as well as the prevalent "Constant Current Constant Voltage" (CCCV) technique to charge the lithium cells. A cell balancing method that relies on economic distribution of charge to the cells from the source, and not on charge shuttling or dissipation between the cells, is proposed.; An FPGA based digital controlling technique for the multi-output converter is discussed along with the detailed design process. Comparisons of analog and different digital controlling technique are carried out with supporting results from the laboratory prototype of the multi-output converter.