一种数字COT控制Buck变换器设计

Design of Digital Constant-on-Time Buck Converter

设计了一种基于数字COT控制的DC-DC变换器。通过分时复用的方法,采用单个ADC实现输入/输出电压和误差电压的量化,并通过内部数字信号计算得到电感电流信息。为克服ADC量程和精度之间的矛盾,使用PGA和DAC实现对6 bit ADC量程的扩展。Buck变换器在输入电压3.3 V、输出电压1.8 V、开关频率1 MHz下进行了仿真验证,输入电压阶跃响应时间从276μs/324μs下降到几乎无影响,负载阶跃响应时间达到39μs/39μs,电源调整率为0.14%,负载调整率为0.14%,输出精度达到了4 mV。

A DC-DC converter based on the current mode controlled by digital constant-on-time(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 μs/324 μs to almost no influence, the load step response time reached 39 μs/39 μs, the power adjustment rate was 0.14%, the load adjustment rate was 0.14%, and the output accuracy reached 4 m V.