The use of a switching power supply to provide the anode, grid and filament power for a vacuum fluorescent display has been the recent subject of numerous papers, periodicals and manufacturers' application notes. This paper, however, develops a math modeling technique that can be used to evaluate many different types of supplies. The results show that none of the power supplies available truly regulate both filament and display power. A control method that could be used to regulate both is evaluated. A simple pulse width modulation control design driving a miniature autotransformer, which results from use of the math modeling technique, will also be evaluated. The electromagnetic interference (EMI) properties missing from most of the evaluations for the other switching regulator power supplies shall be given along with a discussion on designing for low EMI properties.