Logic designers hate two things: analog and power. Many designs don ’t require analog, but power is needed everywhere. Proper distribution of power across a system is critical to a product’s success. An improperly designed system could generate too much heat or not maintain the proper voltage. A power distribution system may work well but be overdesigned, thereby unnecessarily increasing system cost.Today’s distributed power designer must provide a multitude of voltages while up against ever increasing demands on transient load handling. Not every system developer has the luxury of a crack team of power analysts and designers. But following some guidelines can help one to tailor a good power distribution system. In general, there are two basic approaches to power distribution. One is a single-source conversion system. The other is intermediate bus architecture (IBA) conversion that utilizes point-of-load (POL) converters. The new factorized power architecture extends the distributed IBA approach to enhance system performance.
Single-Source Conversion Converting the supply voltage into the required combination of voltages for a system can occur at a single point. Typically, this is done using power bricks that provide isolation and multiple voltages. This approach works well when standard bricks are available that deliver the needed voltage at the appropriate power rating. The difficulty for a designer is finding this match. Otherwise, a brick may exceed a system’s power needs resulting in unnecessary cost.Intermediate Bus Architecture Conversion The IBA approach uses small, low-cost, and high-performance non-isolated POL converters (niPOL). While the ultimate configuration may be a combination of various power architectures, an intermediate bus is likely to prove beneficial in many power systems. The IBA concept is simple. A dc-dc converter is used to derive an isolated, low-voltage bus from the system voltage for distribution to niPOLs. High system efficiency is maintained due to the exceptionally high conversion efficiency of an intermediate bus converter (IBC). Efficiencies above 95% are realized because the IBC does not regulate output voltage. IBCs provide an output voltage that is a fixed-ratio lower than the input voltage. IBA systems can use less board space than an isolated brick converter solution but cost half as much. Cost cuts come from eliminating multiple isolation barriers included in isolated converters. The small size of niPOL converters…Click here to download the PDF version of this entire article.