Design Of Fly-back Peak Current Mode PWM AC-DC Converter XD1230

The microelectronic technology has been developing rapidly, the market demand for power management ICs is also increasing. Various topologies and control techniques have been developed in AC-DC converter, which acts as an important part of the category.This paper is back grounded by the project of "Theoretical research and design of key technique for AC-DC IC based on BCD process", with the Key Lab of High-speed Circuit Design and EMI, Ministry of Education. Based on the principles of SMPS, a peak current mode PWM controller XD1230is designed in this paper. This power management IC works in fly-back converters, which is popular recently.The operation principles of fly-back converters are introduced. In order to accurately predict its behavior, a model based on non-linear state equations has been established, which makes a solid theoretical basis in later designs. This paper derives the values of components in fly-back converters in details, with emphasis on the principles and the modeling method for the transformer, which is the only magnetic component in fly-back converters. XD1230can be directly powered by a high voltage, which saves the charge pump circuits in most AC-DC converters. In light load condition, the controller automatically goes into cycle skipping mode, thus reducing light load consumption. EMI can also be optimized by its unique frequency jittering function. The design process of each core module in XD1230is introduced and analyzed in details.Based on the design of a lμm,5V/20V/700V BCD process, XD1230is verified with the simulation tool Hspice. According to the results, its function and performance both meet the design requirement.