一种分段输出PWM Buck DC-DC转换器设计

Design of a PWM Buck DC-DC Converter with Segmented Output

为了解决PWM DC-DC在轻负载时转换效率骤降的问题,设计了一种分段输出级PWM DC-DC电路结构,用以优化轻负载时的转换效率。该设计引入了负载电流检测电路,对输出电流进行采样并检测。在重载情况下,所有功率MOSFET同时输出。当负载电流减小,逐级关闭各段功率MOSFET,直至在最轻载情况下用最小尺寸的功率MOSFET进行输出。实验结果表明,在1~200 mA负载范围内,电路的转换效率变化较为平缓;在负载为1 mA时,电路的转换效率为81%。

In order to solve the problems that the conversion efficiency of PWM DC-DC dropped sharply at light load, a PWM DC-DC circuit with a segmented output stage was proposed, which was used to optimize the conversion efficiency of light load. A load current detection circuit was introduced to sample and detect the output current. When the load was heavy, all power MOSFETs were output at the same time. When the load current was reduced, the power MOSFETs were turned off from the first stage to the second stage gradually, until the smallest size power MOSFET was only working in the lightest load. The simulation results showed that within a load range of 1~200 mA, the conversion efficiency of the proposed DC-DC converter changed more smoothly. At the light load of 1 mA, the conversion efficiency of the circuit was 81%.