单片降压型DC-DC转换器的控制电路设计

Design of Control Circuit for a Monolithic Buck DC-DC Converter

基于峰值电流检测脉宽调制技术原理,设计了一种新颖的应用于单片降压型DC-DC转换器的控制电路。针对峰值电流采样和PWM比较器电路技术,提出了一种新颖的电路结构。其中,PWM比较器和逻辑及驱动电路由升压电路驱动,节省了一个电平转换电路,降低了电路功耗;PWM比较器直接对功率管和镜像管电流采样,无需使用运算放大器,简化了电路结构。采用华虹宏力BCD350GE工艺进行设计,流片测试表明,电路可实现3V到36 V宽幅输入,500 mA满载输出。在输入24 V电压,输出3.3 V电压时,纹波为2.3 mV。

Based on the principle of peak current detection pulse width modulation technology,a novel control circuit for monolithic buck DC-DC converter is designed.A novel circuit structure is proposed for peak current sampling and PWM comparator.Among them,PWM comparator and logic and drive circuit are driven by boost circuit,which saves a level conversion circuit and reduces circuit power consumption;the PWM comparator directly samples the current of power tube and mirror tube without using operational amplifier,which simplifies the circuit structure.Designed by HuaHong BCD350GE process,the chip tape-out test shows that the circuit can achieve wide input from 3 V to 36 V and 500 mA full load output.When the input voltage is 24 V,the ripple is 2.3 mV at the output voltage of 3.3 V.