Analysis of a Mixed-Signal Control for DC-DC Converters based on Hysteresis Modulation And Estimated Inductor Current

Abstract

This paper investigates a mixed signal voltage- mode controller for dc-dc converters based on hysteresis modulation. Both switch turn-on and switch turn-off instants are determined asynchronously through comparison of the converter output voltage with a voltage ramp driven by the digital controller and generated through digital-to-analog conversion (DAC). With respect to a previously reported mixed-signal solution, the implementation proposed here generates different slope voltage ramps during the switch-on and switch-off phases and it fully approximates the dynamic capabilities of a multi-loop control with an internal hysteresis current control based on the estimated inductor current. Simulation and experimental results on a synchronous buck converter are also reported.