小功率开关电源CLC纹波抑制电路特性分析

Characteristics of ripple attenuates with low power SMPS based on CLC circuit

在便携式仪器中通常使用小功率开关电源为系统供电,电源的纹波噪声直接影响系统的性能。采用MAX606芯片设计了12 V的开关电源,以π型CLC低通滤波器对其输出纹波进行抑制,通过改变电解电容的类型(贴片铝电解、直插铝电解、贴片钽电解)、电容值大小、电感值大小以及负载,分析了CLC电路纹波抑制特性。结果表明,小功率开关电源CLC滤波电路中,电感对纹波抑制作用较大,电容作用较小;贴片铝电解效果最好,钽电解次之,直插铝电解效果最差;应选用mH级电感和100μF以上电容。

The low power switching power supply is commonly used for the system energy supply in portable instruments.And the ripple noise of power supply directly affected the system performance. A 12 V switching power supply based on MAX606 was designed with a π-type CLC low-pass filter to attenuate the output ripple. By changing the type of electrolytic capacitors （SMD aluminum electrolytic, line electrolytic, SMD tantalum electrolytic）, the size of capacitor, inductance and load resistance, the dpple attenuates of CLC circuit was illustrated. The results show that in the CLC circuit of low power switching power supply, the inductance plays an important role in ripple rejection, and capacitor takes the second; the effect of SMD aluminum electrolytic is the best, line electrolytic is the second and SMD tantalum electrolytic is the worst; the capacitance above 100 μF and mH inductance level should be used.