A Design Of Advanced Full Function Integrated Load Switch With Constant Current Operation Mode

Recently, the development momentum of portable electronics power supply system which is based on battery-operated and with USB compatible is very strong. However, due to slower development of battery technology, the drive capability is limited for USB, and a growing number of subsystems require power distribution, the quantity of power supply channel and quality of power provided by traditional PMIC is no longer able to meet the needs of effective power management and high efficiency utilization in modern consumer electronic products. So the design of switch power path management becomes more important, among of which the advanced full function integrated load switch are widely used in power management solutions for portable electronics production due to its comprehensive protection features, low static power consumption, small physical size as well as flexible configuration. In this paper, an advanced full function integrated load switch used in portable electronics production with power path management build in are researched and designed based on complementary mixed signal silicon base(CMOS)process.The research and design of thesis start around low power, low cost, high accuracy, completed protection features as well as easy and flexible testability. The design work includes system define in early stage, circuit design, simulation and verification, layout design and chip testing, whole work implemented in design and test are done to completed the chip.Because of the needs to achieve low power consumption, some redundant circuit can be used in chip are avoid during design work and the circuit block will be implemented in the chip are also designed with power consumption use as little as possible. For the sake of cost down, the components used in circuit are based on basic mask layers, and the design work keep from using components which require extra mask layers usage, such as the NPN bipolar will be replaced by PNP with CMOS base. Due to the needs to achieve high precision of over current protection, the design will employ the trimming technology to accomplish this specification. Since the trends of load switch development are high integration and full function feature combination, so in addition to built in soft start to control the inrush current, over temperature protection and under voltage lock out, adjustable constant current limitation, auto restart, the chip has also integrated the reverse current blocking protection feature, and it is independent of whether the chip is in on state or off state. As the cost of testing become more and more higher in IC development compared with the design work and other portion, this paper present a simple and convenient test mode method, which can be used both in wafer sort or final test, due to it is cable of covering almost all of the basic function and performance for inner circuit in chip, the test mode is preferred to facilitate the testing debug.