Microchip Technology Incorporated
Control of Four-Switch, Single Inductor, Non-Inverting Buck-Boost Converters

Abstract:

A power converter includes a buck leg circuit connected between a voltage input of the power converter and ground, a boost leg circuit connected between a voltage output of the power converter and ground, an inductor connected between the buck leg circuit and the boost leg circuit, an error amplifier configured to compare the voltage output of the power converter against a reference voltage to yield a feedback signal, and a control circuit. The control circuit is configured to generate a reference buck ramp configured to be compared against the feedback signal to determine whether to operate the buck leg circuit in buck mode, and to generate a reference boost ramp by superposing a variable boost ramp portion on to the reference buck ramp, the reference boost ramp configured to be compared against the feedback signal to determine whether to operate the boost leg circuit in boost mode.