| With the rapid development of modern electronic technology, especially the increasing of the type and quantity of the portable handheld devices, integrated power management system has been widely used in communications, computer, consumer electronics and other fields. Integration has become the major trends in power management chip in the future. The topic that how to integrate multiple power management functions in one power management chip has become the research focus in the field of power management chip. While the functions are integrated, what must be considered when the chip is being designed is that how to keep its good performance and lower power consumption.The power management chip XD1528 designed in this paper use integrated power management technology, this paper will integrate the power management functions of Charger and Boost converter into one chip, the power display function based on LED will also be added in. It is in line with the main trend of the power management. This paper gives a detailed introduction of the basic principle of lithium rechargeable technology and the Boost converter, the stability and efficiency of the system are also discussed in detail. Based on this, the design of modules and overall is completed. Charger module uses linear charging architecture, it reduces the complexity of the circuit. Also this paper uses three-stage trickle current constant current constant voltage charging method. It will be more conducive to protect the battery, preventing overcharge or less charge. The charging current will be reduced before the battery voltage reaches saturation; when temperature is over, the charging current is reduced to reduce temperature, rather than directly shut down the charging circuit, the above two points are the innovation of this part. Boost converter module uses synchronization architecture and selects peak current mode control mode, it can achieve a stable 5V output and provide maximum load current of 2A. Based on the fact that the chip is using the energy stored in the battery as the power source in practical applications, therefore, how to control the power loss to the minimum value will become the key design. This paper adopts two approaches: firstly, Boost module uses synchronous rectification technology and PWM/PSM hybrid modulation. When Boost converter is overloaded, PWM is used, when it is in light load, PSM is used. This can greatly reduce the loss, especially in the lowest system efficiency in light load or no-load; secondly, standby mode is introduced to the system work, when the system is in non-charging state and the load current is less than 35 m A, the system enters standby mode, the vast majority of circuit module will be shut down. When recharging or connecting to a large load, system re-enters the normal operating mode. By using these two methods, the loss of the system is reduced greatly, extending the battery life. Power display module uses the popular display mode in the market. Power display module uses four LED to indicate the size of the battery, it will make users to know the stored energy when charging and the remained energy when discharging easily and clearly. This will be more convenient for practical applications.The chip uses 0.35?m standard CMOS process. In the Cadence platform, the design and simulation of each sub-module and the overall has been done. The results indicate that the chip's performance and index parameter match the design goals. The chip designed in this paper matches the integrated development trend of power management chip, the market prospect is well. The chip has already completed flow sheet, currently awaiting further test results. |
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