The Design Of High Voltage High Efficiency DC/DC Converter Based On BCD Process

With power electronic technology has been developing to high frequency and high integration,switching power supply 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 using 0.5um 20V BCD process. The converter uses buck DC/DC topology and pulse width modulation controller. It has a very high efficiency, up to 95% .In this thesis, firstly,the basic principle DC/DC switching converter is introduced, and topology of the operational principle of current mode PWM controller is further analyzed in details.Then every subcircuit is designed reasonably according to the principle and character of PWM switching converter, such as:bandgap, over temperature protect circuit, error amplifier(EA), PWM comparator, oscillator, output stage, bootstrap circuit and so on.It is analyzed in detail that how to realize every subcircuits'functions according to different needs. Then, the paper used the tool of Cadence, finished circuits design in transistor level and functional simulation. These simulation results indicated the circuit design according with the requirement.The converter has a wide 4.5V to 24V operating input range and output range adjustable from 0.81V to 15V. It has 1.2A peak output current. The converter has a fixed 1.4MHz frequency, when the output voltage falls below a certain value, the frequency of the oscillator will be reduced to 460kHz. 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, LED drivers and so on.