Digital Control of Single-Inductor Dual-Output dc-dc Converters in Continuous-Conduction Mode

This paper investigates the application of digital control for non-isolated single-inductor dual-output step-down dc-dc converters operating in continuous-conduction mode (CCM). The accurate and independent control of each output requires sophisticated digital control architecture so as to minimize cross-regulation problem. The adopted control includes a separate regulation of common-mode and differential-mode output voltages. Moreover, variable gain of the differential-mode regulator and a non-linear evaluation of the common-mode voltage have been investigated in order to improve the system dynamic response at different load conditions. Experimental investigation has been performed using discrete components, implementing the digital control in a field programmable gate array (FPGA). Simulation and experimental results on dual output converters (Vin =2.5/5 V, Vo1=Vo2=0.9/1.5 V, Io1=Io2=0/0.6 A) confirm the proposed analysis.