| Nowadays,the electronic information technology develops dramatically with each passing day.Intelligent mobile phone,tablet computer,camera,wearable devices and other portable products emerge in an endless stream,which not only brings great convenience to people's lives,but also stimulates the economic development.However,with the increasing richness of functions and performance enhancement of portable devices,the standby problem becomes increasingly prominent.In order to improve the bad user experience caused by this problem,either the battery capacity can be increased or the charging time can be shortened.But the specific capacity of battery is difficult to break through because of the slow progress of battery materials and processing technology,while the volume increase in exchange for capacity runs counter to the thinning trend of portable equipments.Therefore,the fast charging technology gets a rapid development as the best solution at present.The essence of the fast charging scheme is to improve the charging power,which is mainly achieved by increasing the current and raising the voltage.The first method requires special customization of hardware such as charging line,charger and battery,otherwise it will lead to increased power consumption and can not realize the true significance of fast charge;in contrast,the second way has a stronger compatibility with the hardware and has received a higher degree of attention,but the power increase problem of the internal DC-DC converter is inevitable due to the direct boosting.In view of the above problems,a lithium battery charging interface chip XD9523 is designed in this paper which is compatible with a variety of charging protocols on the basis of high voltage fast charging scheme.As a bridge between the adapter and the terminal equipment,this chip is mainly to complete functions such as recognition of the charging protocol,charging current real-time tracking detection and feedback control.The design and implementation of the program have gone through the following stages:(1)Access to information and decide the realization scheme of this design on the basis of understanding of the existing fast charging technology;(2)Develop the chip specification and determine the system level design scheme and the concrete implementation architecture;(3)Divide the whole system into function modules and carry out the specific module design;(4)Verify the functions of the key sub-modules and the whole system by simulation.In this paper,the Cadence software is used as the design and verification platform,and the Spectre simulator is used to carry out schematic design,parameter analysis and functional verification,while the AMS mixed signal simulation is adopted to realize the function validation of the overall system.The simulation results obtained show that the chip has a complete charging protocol identification function,including USB DCP charging protocol such as divider1/2/3,BC1.2 and QC3.0 and USB Type-C interface protocol.In addition,constant power control is achieved in the fast charging stage,that is,keeping the output voltage changing in small steps while maintaining a relatively constant charging power,which ensures that the battery can be charged at a constant maximum constant power at low SOC,improves the power consumption of the boost scheme,and realizes a high degree of compatibility and reliability.In this paper,the lithium battery charging interface chip has been designed which alleviates the bottleneck problem caused by the lack of portable equipment endurance,and plays a significant role in the development and popularization of the fast charging technology. |
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