Multiphase digital integration constant on-time-controlled Buck converter with high-resolution current balance scheme for ultrafast load transient

In this paper, a multiphase digital control called digital integration constant on-time (DICOT) control is proposed, which applies the concept of signal accumulation, solves the drawbacks of ripple-based digital COT control that the switching frequency and transient performance are affected by the A/D sample delay and sampling noise. Besides, the multiphase interleaving approach of the proposed DICOT control is well-suitable for digital control and no higher calculation frequency is required compared to single-phase. In the aspect of the current balance, almost all existing researches work on analog COT current balance scheme and few works are investigating the resolution improvement of digital COT current balance. In this paper, the current balance model of multiphase COT control is derived and can be applied in the Buck system with an arbitrary number of phases, the delay-line-based high-resolution COT current balance scheme is proposed to enhance the control resolution. Finally, the two-phase DICOT control is tested on the multiphase Buck system, the transient performance is tested of 100 A load step with the slew rate of 1000 A/mu s, and the voltage undershoot and overshoot are 20 and 36 mV, respectively. The current balance is tested and the errors are 0.01% and 0.11% at the light and heavy loads, respectively. This paper proposes a multiphase digital integration constant on-time (DICOT) control algorithm and a delay-line-based high-resolution COT current balance scheme. The proposed DICOT control is more suitable for digital control and can be applied to the multiphase Buck system with an arbitrary number of phases.image