How to build a better DC/DC regulator using FPGAs

Adam P. Taylor, EADS Astrium
EETimes (11/2/2011 3:07 PM EDT)

Designers traditionally build switch-mode DC/DC converters using analog components (bespoke ICs, operational amplifiers, resistors, capacitors and the like) to control the feedback loop and to generate the pulse-width modulation required for switching. When using analog components like these, you must consider a number of factors, taking tolerances, electrical stresses, aging drift, and temperature drift into account to ensure the stability of the design. Now, the availability of affordable low-powered FPGAs coupled with analog-to-digital converters allows the FPGA to replace the traditional analog approach.

DC/DC converters are designed in one of four main topologies: buck (step-down), boost (step-up), inverting (converting a positive input to a negative output), and SEPIC (single-ended primary inductor converter). SEPIC devices maintain a constant output voltage, stepping the input voltage up or down depending upon the circumstances. For this reason, they are a popular choice for battery-based applications.

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