A Hybrid Constant On-Time Mode for Buck Circuits

Abstract

To achieve a designed and fixed operating frequency for a controller with high dynamic performance and a high load capacity, a hybrid constant on-time (COT) voltage mode for a Buck circuit is proposed and discussed in this paper. The proposed hybrid strategy is a combination of the classical COT method, a dynamic reference voltage technology and a proportional–differential (PD) module. The workflow is demonstrated in brief, simulations of a Buck circuit with the proposed hybrid COT mode are conducted and comparisons with developed pulse-width modulation (PWM) technology and the hysteresis mode are made. The results show that, with the help of the proposed control scheme, impressive performance from the Buck circuit can be expected. The operating frequency can be fixed well by the hybrid technology without losses of performance and robustness in steady state and will not jump much even with the sudden change of the inputs and the load. The proposed control strategy contributes to the foundation of circuit design and optimization.