关键词: 数字电路；COT控制；电流模；Buck变换器

Abstract: In this paper, a DC-DC converter based on the current mode controlled by digital COT is designed. By time-sharing multiplexing, a single ADC is used to quantify the input/output voltage and error voltage, and the inductance current information is obtained by internal digital signal calculation. In order to overcome the contradiction between ADC range and accuracy, PGA and DAC were used to extend the 6 bit ADC range. The Buck converter was simulated and verified at 3.3 V input voltage, 1.8 V output voltage and 1 MHz switching frequency. The step response time of the input voltage dropped from 276 s/324 s to almost no influence, the load step response time reached 39 s/39 s, the power adjustment rate was 0.14%, the load adjustment rate was 0.14%, and the output accuracy reached 1.95 mV.

Key words: digital circuit; constant-on time; current-mode feedback; Buck converter