| With the power electronic technology has been developing to high frequency and high integration,The switching power supply had became a hotspot in the field of power electronics.The new types of PWM controller are the most important.In this thesis, a buck DC/DC switching converter is designed to use EPISIL 0.8?m BCD 12V/5V/30V 2P2M Psub (DF3) process. The converter uses pulse width modulation controller. It has a very high efficiency, up to 95% .In this thesis,the basic principle DC/DC switching converter is introduced firstly, the buck topology and current mode PWM controller are further analyzed in details.Then after the analysis of the system stability,the slope compensation and system frequency compensation are used. Meanwhile, the small-signal model of the system is established and used to verify system stability and predict performance.According to the specification of PWM switching converter every subcircuit is designed reasonably,such as:bandgap, error amplifier(EA),current sense amplifiers,PWM comparator, oscillator,and so on.It is analyzed in detail that how to realize every subcircuits'functions in different needs.Then, the paper used the tool of Cadence, finished circuits design in transistor level and functional simulation. These simulation results indicate the circuit design well satisfied the requirement. At last the layout is designed and the test result of the chip is listed. The converter has a wide 4.75V to 23V operating input range and output range adjustable from 0.91V to 16V. It has 2A output current, 0.1uA shutdown mode current.The converter has a fixed 380KHz frequency, when the output voltage falls below a certain value, the frequency of the oscillator will be reduced to 240kHz. The converter also has the function of OTP,OCP and short protect.Current mode operation provides fast transient response and eases loop stabilization. It can be widely used in the field of distributed power systems, battery charger and DSL Modems and so on.
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