Digital CPM Controller for a Non-Inverting Buck–Boost Converter With Unified Hardware for Steady-State and Optimized Transient Conditions

This paper introduces a new current-programmed controller for non-inverting buck-boost (NIBB) converters. The controller facilitates tight voltage regulation and excellent transient convergence, all carried out through a simple current programmed mode (CPM) controller hardware. Steady-state operation for the full range of conversion ratios is supported with seamless transitions between modes and improved efficiency and ripple characteristics around unity conversion gain. In case of a load transient, an optimized boundary control scheme achieves near-optimal recovery, with programmable constraints for the voltage deviation and inductor current, covering the entire range of conversion ratios. The operation of the controller is experimentally verified on a 2-15 V input to 3.3 V output, NIBB converter, demonstrating a significant improvement in steady-state around unity gain as well as fast convergence for load transients with programmable constraints for the output voltage deviation and inductor current.