Audio-Susceptibility in Peak Current Controlled CI-SIDO Buck Converter

The current trend towards miniaturizartion of consumer electronics have led to, rapid adoption of single input multi-output (SIMO) class of DC to DC converters. SIMO class of converters are fast replacing the single input single output(SISO) class of converters. SIMO DC to DC converters are capable of providing multiple regulated voltage levels, for various auxilliary units present in consumer electronics. This paper introduces a specific SIMO converter: the coupled inductor based single input dual output(CI-SIDO) buck converter. The input voltage fluctuations fed to CI-SIDO buck converter affect the output voltages of these converters. This phenomenon is called audio-susceptibility. As, CI-SIDO converters, need to have strictly regulated output voltages. The effect of input voltage fluctuations need to be studied extensively, for proper design and operation of CI-SIDO buck converters. Peak current mode(PCM) control is a commonly used controller in regulated DC to DC converters. The two control loops that make up PCM control are the outer voltage loop and the inner current loop. Current literature lacks investigation of the inner current loops effect, on audio-susceptibility of CI-SIDO buck converters. This paper develops a complete small-signal(SS) block diagram model of PCM controlled CI-SIDO buck converter. The effect of PCM control inner loops on audio-susceptibility of CI-SIDO buck is investigated using the developed model. The audio-susceptibility due to PCM inner loops, are shown using MATLAB Simulink, and the open-loop audio-susceptibility is used to compare the outcomes.