Design Of Low Noise And High Current LED Charge Pump DC/DC

This paper is based on the project"Theoretical research and design of key technique for deep-submicron power management IC"and mainly deals with the design of low noise and high current LED charge pump DC/DC converter. A CMOS charge pump switching voltage converter IC, named XDJ6316, is described detailly, including definition of the IC specification, further analysis of the electrical characteristics, and implement of subsystem circuits and simulation of the whole chip.The basic principles of charge pump DC/DC converter which is the theory guidance of the design and the implementation of XDJ6316 have been analyzed and studied in this paper. The chip includes a current source capable of driving loads LED up to 1A from a 2.9V to 4.4V input. Independent low and high current settings are programmed by two external programming resistors. Shutdown mode and current output levels are selected via two control logic inputs. It will automatically switch from 1x mode to 1.5x mode, and subsequently from 1.5x mode to 2x mode whenever a dropout condition is detected. The main switches will connect supply input with output in 1x mode until the output voltage has decayed to less than or equal to the voltage at the supply input. In addition, lots of protection circuits are integrated in the chip, such as thermal protection, soft-start, overcurrent shutdown, and so on.The chip is a novel analog IC based on the 0.6μm standard process. All simulations have been completed under various supply-voltages and operating-temperatures by using the EDA software, such as Workview and Hspice. The results of simulations indicate that the function of XDJ6316 is excellent with a 4% LED current programming accuracy as well as 1x, 1.5x and 2x output voltage. And all of other characteristics meet the specification too.