Design and implementation of step-down converter with D-Σ digital control

This paper presents design and implementation of a dc/dc converter with division-summation (D-Σ) digital control. With the control, the converter is allowed to have wide inductance variation caused by high current flowing through inductor, and to track current reference precisely for achieving tight output voltage regulation. Moreover, the control can reduce steady-state error as compared with peak current-mode control and achieve faster dynamic response over average current-mode control. This paper also presents a precise current reference calculation to avoid sub-harmonic oscillation of inductor current under discontinuous conduction mode. Experimental results have verified the analysis and discussion.