高频PWM DC/DC转换器设计

Design of high frequency PWM DC/DC converter

设计了一种基于2．5μm 40V双极工艺的高频低功耗的PWM升压型DC／DC转换芯片．采用了恒定频率、电流模式的控制结构以提供优秀的电源和负载稳压．同时内部的电流监视电路可以保护功率开关以及连接到芯片上的外部元件．通过对开关脉冲宽度的调节，加快了升压速度，减小了稳压状态的输出纹波，提高了转换效率．仿真结果表明，在2．7～12．0V的输入电压范围内，芯片的开关频率为1．2MHz，开关电流限制值为1．2A，转换效率可达85％以上．使用很小体积的外围元件就可获得满意的输出纹波，在很小的电路板面积上产生大电流输出，降低了电路尺寸和成本．

A high frequency PWM step-up DC/DC convert with low power dissipation was designed by using 2.5μm, 40 V high voltage bipolar process. The chip uses a constant frequency, current-mode control scheme to provide excellent line and load regulation. Internal current-monitor circuit helps protect the power switch as well as the external components connected to chip. Regulating pulse width can accelerate the step-up speed, reduce the output ripple voltage and improve the conversion efficiency. The testing results showed that the input voltages were within 2.7-12.0 V, the conversion efficiency 85 % and PWM switching frequency 1.2 MHz, the switch current limit is set to 1.2 A. Using the converter, few size external components are used to achieve satisfied output ripple voltages and high current outputs can be generated in a small footprint.