峰值电流控制开关电源的反馈补偿问题研究

针对电流控制模式降压型开关电源芯片，探讨了输入电压的不同以及工作温度的差异造成对输出带负载能力和峰值电流的影响。在电流反馈回路的斜坡补偿模块中，加入随输入电压线性变化的基准电流源，以补偿不同输入电压对采样与斜坡补偿峰值电压造成的差异。此外，对反馈环中的比例电阻采用不同的工艺制作，通过电阻的温度系数补偿由采样电阻随温度变化所造成的采样电压的变化，减小温度对电路的带负载能力和峰值电流的影响。改进后，在相同环境温度下，4．7V到30V输入时，输出最大负载电流差异由2A降为0．5A。电阻改进后，从27℃到150℃，输出最大负载电流几乎不变。

Research on Feedback Compensation Problems of Peak Current Control Switching Mode Power Supply

The impact of the different input voltage and environment temperature on the loading capacity and peak cur rent are discussed for peak current control DC-DC switch power chip. In the module of slope compensation the linearity changed benchmark current source is applied to compensate for current feedback loop, the difference of sense voltage and slope voltage caused by different input voltage. Furthermore, the process of proportion resistance in the feedback circuit is changed, and the change of sampling voltage caused by sampling resistance with temperature changes is compenstated with resistance temperature coefficient. The impact of environment temperature on loading capacity and peak current is reduced. With the circuit improved, the difference of the most loading current is reduced from 2 V to 0. 5 V with 4. 7 V-30 V in the same working temperature. The most loading current is almost unchanged at 27 ℃-150 ℃.