一种PWM/PFM的同步整流升压转换器设计

The Design of a Synchronous Step-up Converter with PWM/PFM Switching Control

文章介绍了一种工作在PWM/PFM双模式下的同步整流升压转换器设计,剖析电路的工作原理,采用0.35μmn阱CMOS工艺流片。通过SPECTRE仿真器模拟,结果显示该电路在输出负载电流是1mA时,输入电源电压0.9V启动,在关机模式下静态电流小于1μA,输出电压调节范围2.5V～5V,输入电压1V～5V,固定频率1.4MHz,允许采用外形扁平而小巧的电感器和陶瓷电容器,从而极大地节省了PCB板的面积,效率高达92%,可以从单节AA电池产生3.3V/260mA的输出或从双节AA电池产生3.3V/600mA的输出。该器件包括驱动管NMOS和同步整流管PMOS,具有斜率补偿的电流模式PWM设计,减少了外部元件的数量。抗振铃电路通过在不连续工作模式下对电感器进行阻尼来抑制EMI。在轻负载情况下工作在PFM模式,重负载情况下工作在PWM模式。

A synchronous step-up converter with PWM/PFM Switching control. The structure and principles were analyzed and simulated by using 0.35 μm n-well CMOS process. The Spectre simulation results show, power supply achieving up to 0.9V works at 1mA. The quiescent current is less tan 1 μ A in standby mode, efficiency achieves up to 92%.The devices work under the input voltage between 1.0V and 5V with a 1.4MHz fixed frequency switching .These features minimize overall solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors.The devices is capable of supplying an output voltage between 2.5V and 5V. The devices featured providing up to 260mA from a single AA cell input or up to 600mA from a 2-cell AA with a 3.3V output.The devices contain an driving NMOS and PMOS synchronous rectifier. The current mode PWM design is internally compensated, reducing external parts count. Antiringing circuitry reduces EMI concerns by damping the inductor in discontinuous mode.It works in PFM mode at light loads,and works in PWM mode at heavy loads.