开关电源IC中误差放大器的自激振荡及解决方法

摘要

The error amplifier in the switchmode power supply control IC is one of the operation amplifier. Although most of them are compensated, oscillation is sometimes produced by the influence of the components and the other factors outside.As an example, the self-excited oscillation of the error amplifier in UC3875 is analyzed. We use a sero created by a phase compensate network to counteract the pole created by components and the other factors outside. Through experiment, this compensating method is effective in restraining the self-excited oscillation.%开关电源控制IC内部的误差放大器是一种运算放大器,尽管大多数都进行了相位补偿,但由于外部元件等因素影响也会产生自激振荡.以UC3875为例,分析了其内部误差放大器的自激振荡,并用外部补偿网络对其进行补偿,使用一个零点对外部电路产生的极点进行抵消,从而抑制其自激振荡.通过实验验证,此补偿方法可以有效抑制误差放大器的自激振荡.