Design Of A Low Voltage Start-up Boost DC-DC Converter Control Chip

In recent years,more and more smart wearable devices have emerged in the market.Portable smart wearable devices put forward higher requirements for boost DC-DC converter.How to make the chip work in low-voltage environment,and have low static power consumption and high conversion efficiency has become an important research direction of DC-DC converter.In this paper,through the in-depth analysis of the working principle,working mode and different negative feedback modulation modes of boost DC-DC converter,according to the design requirements of low-voltage start-up and low static power consumption,the hysteresis current mode control mode is adopted as the system control scheme.Firstly,the design and analysis are carried out from the system level,and the loop stability,the selection of peripheral devices and the circuit loss of the system are analyzed to ensure the stability and efficiency of the system.And a variety of hysteresis window generation modes are compared,and the hysteresis comparator scheme with simple structure and low power consumption is adopted.Finally,based on GSMC 0.18μ The module and the whole circuit are designed and verified by Cadence simulation software.The starting circuit,zero crossing detection circuit,hysteresis comparator circuit and full cycle sampling circuit are mainly studied.The simulation results show that the boost DC-DC converter designed in this paper can boost from 0.7V to 5V,the load current range is 5 m A to 300 m A,and the output voltage can be adjusted by changing the voltage feedback network resistance.When the voltage is 0.7V to 5V,the voltage ripple of the circuit is less than 10 m V in CCM mode and less than 5m V in DCM mode,and the built-in zero crossing detection module can realize the automatic conversion between CCM mode and DCM mode when the load jumps,so that the efficiency can reach 70% when the load current reaches 15 m A,and about 80% when the load current reaches 50 m A,When the load is 200 m A,the efficiency can be as high as 91%.