A Design Of A Multi-Model Lithium Battery Chip

As technology advances, the applications for portable devices increase. The use of lithium batteries is more extensive,too.It gradually penetrates into both economic and social fields. How to charge the lithium battery has been a hot research point.This paper analyzes the development history of power management technology and switching power supply technology.Then, it introduces the significance of this issue.It also presents the charging technology of lithium battery.It compares several advantages and disadvantages of different ways. Finally, we designed a suitable multi-mode portable devices lithium battery chip.First, we know the feather and some basic index of lithium battery chip.And then we begin to design the sub module of the chip. The chip we designed can charge quickly and efficiently. The charging mode is constant current-constant voltage(also called three-stage charging). The input voltage is high,and it greatly extends the scope of application. In addition, this chip has three operating modes: charge mode, boost mode,high-impedance mode. The synchronous BUCK PWM converter with high freqence has a wide range of duty cycles. Moreover, the switch of different modes is controlled by the I2 C interface. The chip contains a highly integrated switch-mode charge circuit. It can be charged by an external USB power supply,and it also contains a internal boost regulator. So, the chip can be used alone to charge USB devices.The chip has many functions such as over-temperature protection, under-voltage protection and so on.These functions can ensure the chip work in a stable and secure environment.According to design requirements,we respectively design the reference voltage module, the oscillator, the under-voltage protection and the over temperature protection.We checked a lot of papers and data, and we thought deeply about these four modules.We listed many circuit structures and made an assess about different structures.After the design is completed, we used both Cadence and Hspice circuit simulation software to simulate the four modules. The simulation results meet the design requirements. Then we simulated the some key features of the whole circuit, the results are consistent with the design requirements of the index, finally.