The Design Of Single-chip AC/DC Switching Power Supply Management IC

Single-chip switching power supply management Integrated Circuit (IC) has many virtues such as high integration level, most cost effective, lowest component count switcher solution, and high performance. Its being used can form high efficiency insulated switching power supply without using utility power transformer. The switching power IC is selected firstly in the design of high power switching power supply, precision switching power supply, application specific switching power supply and so on in the world, which has been making switching power supply short, small, light and thin.Based on CMOS technology and using the tools of Cadence EDA, a type of single-chip switching power supply management IC is designed for the switching power supply of AC/DC. It works at high frequency with pulse width modulation (PWM) mode; the working frequency is fixed at 100 KHz. So far as the output signal of the single-chip IC is concerned, the maximum time proportion of its high level is 62 percent, but the minimum one is 7.5 percent, In sum, the single-chip IC is mainly used in charging devices such as battery charger.In this paper, the basic theory of PWM mode is given firstly. Then the total structure of the IC is present according to the function requirement. Based on its actual application, the working theory and the working principle are showed. In the meantime, the all sub-circuits are also designed and emulated carefully including inverter, AND gate, OR gate, RS type flip-flop, 8 frequency divider, voltage reference circuit, error amplifier, voltage comparator, sawtooth-wave generator, PWM comparator, Soft activation circuit, Power-up reset circuit, uder-voltage protection circuit, thermal shut-down circuit and so on. As a result, all of the sub-circuits answer the requirements.What is more, the synthetic circuit is emulated about power-up working, normal working, automatic restart working and over-current working; the results of emulation meet the function requirement. The forward design of Single-chip switching power supply management IC has been finished.At last, the usage of software of Cadence EDA in design is introduced in this papar.