The Research Of Amplifier And Relative Protection Circuit In Power Switch Supply Control Chip

With the development of electric power and electron,the relationship between the equipment of electric power and electron and human-being is getting more and more consanguineous,and it is well known that any equipment can work without power supply. Power supply can be divided into two kinds,which are linearity power supply and switch power supply.Switch power supply is applied at large nowadays because of its low consumption,high efficiency and simple circuit configuration.So it is widely used in computer,electronic equipment,communications equipment.Switch power supply is becoming light,small,thin and high efficiency.A new type of current-mode,low consumption single-chip controller is designed for the fly-back switching power supply of AC/DC.The keystone is the research and simulation of protective circuit.Firstly,study the operation amplifier which is widely used in switch power supply carefully.Design for a new scheme for rail to rail operational amplifiers.The configuration is adopted 0.35um process of charter to draw layout,do post simulation and tape out.The common level of input stage is kept constant by floating gate transistors and feedback circuitry. Also,as the middle stage,a folded cascade added by assistant operation amplifiers is employed to advance the performance.The new configuration has a wide input range,little fluctuation of gm,high gain,large bandwidth and SR.What's more,it takes up less area. When the power supply is -1.5V—+1.5V and the input voltage range is -5V—+5V.,the gm variation of input differential transistors is 3%;when the input common voltage range is -2.5V—+2.5V,the gm variation of input differential transistors is 0.7%.The gain is 68dB. Bandwidth is 4.73MHZ.SR+ is 33.6V/US,SR- is 35V/US。Secondly,design and simulate bipolar protective circuit.The detailed modules of bipolar protective circuit are Oscillation,Limit current protection,1.8V compare,PWM comparison, Over voltage protection,Slope current drive,Voltage adjuster,Slope compensation,Voltage reference.Lastly,design and simulate CMOS protective circuit.The detailed modules of CMOS protective circuit are over-temperature protection,digital logic circuit,comparison,Limit current protection,over-voltage protection,LDO,soft-startup.