Research And Design Of Large Current High Efficiency Switched Capacitor Divider

Consumer electronics products are developing rapidly,which brings new requirements for power management technology.In a variety of types of DC-DC converters,switched-capacitor converters are increasingly favored for their integration,high power density and low noise.Load capacity and system conversion efficiency are the main factors limiting the commercialization of switched-capacitor converters.Starting from the market demands for portable devices,combined with the current research hotspots of switched-capacitor converter,a two phase switched-capacitor voltage divider with large current and high efficiency is proposed in this thesis.The input voltage of the voltage divider system designed in this thesis is 5?10.5 V,a maximum output current of 5A,and a minimum output current of 5mA.Due to the open-loop control method,no compensation circuit needs to be designed.Focuing on system efficiency optimization under wide load range,a novel charge transfer technique is proposed to reduce the dynamic loss of power transistor,in the meantime,frequency reduction method is adopted to improve the light load efficiency of the system.Aiming at the problem of surge at the moment of power on,the soft start is designed.In addition,a voltage pre-regulator module based on bandgap structure is designed to supply power to the low voltage modules in a wide input voltage range,which reduced the complexity of system design and improved reliability.Moreover,this chip is also designed with input under voltage protection,over temperature and current protections to ensure the safe operation of the switched-capacitor converter.The chip is designed with Global Foundries 0.18?m BCD(Bipolar CMOS DMOS)process.The simulation results show that the chip can start normally when the power is on,and the system response with load jumping conforms to the design expectation.The test results demonstrate that the two phases of the chip work normally,and the maximum operating frequency of the systcm is 500KHz.At 1A heavy load,the output voltage ripple is only 23mV.At light load,the system operating frequcncy is significantly reduced,and with 67mV output voltage ripple.System efficiency consistently exceeds 60%and peak efficiency exceeds 93%in the test load range.