1MHz单周期控制同步整流Buck变换器的设计

摘要

An effective way to improve the power density of a power converter is to increase the switching frequency. The switching frequency of the traditional one-cycle controlled chip IR1150 is limited to 200kHz. Therefore, an im-plementation scheme of a one-cycle controlled synchronous buck converter with 1 MHz switching frequency was pro-posed. A combination of UC3825 and TPS28225 was used in the control circuit with UC3825 as the main chip and TPS28225 as the drive chip. The working principles of the system were analyzed and the design guidelines were pres-ented as to the main switching device, synchronous rectifying device, output filter and the integrator. A prototype with 1. 8V and 5A output was made, and its efficiency could rate up to 80. 74 percent. The experimental results verified the effectiveness of the proposed scheme.%提高功率变换器功率密度的有效方法是加大开关频率。传统的单周期控制芯片 IR1150只能工作到200 kHz的开关频率,为此提出了一种1 MHz工作频率的单周期控制同步整流Buck变换器实现方案,控制电路采用“UC3825+TPS28225”这两款芯片实现,其中UC3825作为主控芯片,TPS28225作为驱动芯片。分析了整个系统工作原理,并对同步整流Buck变换器的主开关管、同步整流管、输出滤波器和积分器等进行了详细分析及设计。制作了一台1.8V、5A输出的样机,样机运行稳定,额定效率可达80.74%。实验结果验证了该设计方案的有效性。