“One advance in technology could have a big impact on PDN design: the incorporation of nonlinear features into DC-to-DC converter control loops.”
The trend in power distribution network (PDN) design has been to support tighter voltage tolerances and higher currents. Market demands are forcing design engineers to create designs that push tighter specifications. Meeting these specifications means creating PDNs that service greater device density with higher power efficiencies and, in many cases, at lower cost. All these requirements make the whole design process more difficult.
The standard approach in PDN design is to use a target impedance methodology in which we design to a target impedance calculated by the worst-case voltage fluctuation we can tolerate divided by the worst-case current excitation we can expect. The goal is to have a PDN that operates below the target impedance over the bandwidth of the load the converter is supporting. As current demands rise and voltage fluctuation tolerances fall, we must lower impedance further with higher-density capacitance. This shift requires the use of more expensive parts, such as capacitors capable of surviving the higher heat that will be created by the higher currents in a denser design. It’s necessary to balance all these factors when designing a PDN.
This is an excerpt from 7 Experts on New Approaches for Power Distribution
Network Design. The eBook was generously sponsored by KEMET Corporation and Mouser Electronics.