Switching Power Supply For Driving LED

With the prosperous development of electronic science and technology, the power supply has become an indispensable part to modern electronic equipments. What's more, the Switching Power Supply, featuring high-integration, high ratio of performance to cost, simple peripheral circuit and high efficiency, has been more and more familiar to people. By virtue of HSpice tool, a kind of DC/DC switching power supply chip has been designed, which utilizes the charge pump to fulfill the double increase on output voltage.The chip ensures the regulated 5V voltage output,in condition of no load, in the range from 2.8 to 5V of input voltage. Bandgap, softstart, and error-amplifier module all play important roles in the whole chip:Bandgap is used to supply a benchmark characteristic of low temperature coefficient, high accuracy and high stability, serving as the reference of other modules; Softstart effectively reduces the in-rush current when start-up and mode-changing, guaranteeing the normal operation of the chip; Error-amplifier is able to sensitively detect the change in output voltage, realizing the steady 5V output, in condition of no load, and 15mV with worth of ripple in condition of 60mA load. In addition, low quiescent current 0.3mA, over current protection threshold 250mA, short circuit current 50mA, as well as two types of charging mode also glitter the chip's performances.This paper firstly researches the operation principle of switching power supply, related hierarchy design corresponding to the necessity, and detailed sub-module structure's building. Then with the help of HSpice, the expected indices have been successfully achieved. Last, in the Cadence environment the layout of whole chip has been finished and passed the DRC, LVS verification as well.