一种应用于直流电压转换芯片的新型数字软启动电路

A Novel Digital Soft-Start Circuit for DC-DC Switching Regulator

提出了一种新型的用于高效率、低功耗双模式直流电压转换器(DC-DC)芯片的数字软启动电路。该电路采用数字分频和电流限制电路相结合的设计方法实现了软启动的功能,避免了常规设计中使用大的启动电容,因此容易实现全集成的设计,可减小面积、降低成本。芯片采用CSMC公司的0.5μmCMOS混合信号模型设计和流片。测试结果表明这种数字软启动电路约在750μs内完成软启动的功能,避免了启动过程直流电压转换器(DC-DC)芯片中的浪涌电流和输出过冲电压的现象。

A novel digital soft-start circuit, used in a high-efficiency, low-power dual-mode DC-DC converter, is presented. The soft start circuit was designed on the base of frequency divider and current limit circuit. Therefore,it avoids a large soft-start capacitor which was used in the traditional design. It could be fully in- tegrated on a chip, leading to the reduction of the board space and component cost. The chip was implemented by using CSMC 0. 5μm CMOS mixed-signal process. Chip test results indicate that the process of softstart can be carried out in approximately 750μs. Thus, the circuit could effectively eliminate the inrush cur- rent and avoid the overshoot of the output voltage.