Design Of Single Inductor Dual Output DC - DC Converter With Dynamic Voltage Regulation

With the rapid developments of electronic products, such as smart phone, PAD, electronic books, music player and so on, have become an essential part of people’s life. The contradiction between the more features and the time of electronics’ endurance is becoming more and more serious. High efficiency is critical for a power management chip and is also consistent with the concept of environmental friendly. The topology structure of the power stage and control loop is the core of the study in the DC-DC converter system. The single-inductor multiple-output (SIDO) DC-DC converter has become a research hotspot in recent years since it can provide more than one output using only one inductor only. Some parts of the electronics can still function well with low voltage that can reduce power consumption effectively. As a matter of fact, many electronic products have dynamic voltage scaling (DVS) function which requires power management system provides programmable voltage outputs.A single-inductor dual-output DC-DC converter having one output of0.7V-1.2V and another output can be1.2V/1.8V is presented. Dynamic voltage scaling is applied on V2which gets control data through SPI. Both channels can have the maximal load current of500mA. The converter can switch between pulse-frequency modulation (PFM) and pulse-width modulation (PWM) mode automatically according to load condition that can improve the system efficiency under light load condition. Adaptive dead time adjustment is introduced in the system to improve efficiency and the segment driving for power switches is implemented to reduce spikes. This converter has been fabricated in0.25-um CMOS mixed signal process. The peak conversion efficiency can reach90%. Adaptive dead time adjustment function can enhance the system efficiency3%to5%. The cross regulation is limited within40mV under DVS.