Design Of An AC-DC PWM Controller Based On BCD Process

With the rapid development of the electronic technology, the application of electronicsystem is more and more wide, and any electronic equipment cannot work without reliableregulated power supplies. Switch power supply is considered as the energy-efficient power. Itrepresents the direction of the development of regulated power supply, and becomes themainstream product. BCD process is an advanced single-chip integration technology, whichhas the following advantages: high efficiency、high integration、high performance price ratioand the simplest peripheral circuit, so its market prospect is broad. Therefore, the study of therelevant process and products has important economic value.An AC-DC controller based on CSMC0.5um40V BCD process is presented, it isapplied in portable adapter and works in peak current control mode. The development history,trend, fundamental and application of BCD process are introduced first; Then, through theresearches on the withstand voltages and on-resistances of high/low-voltage devices andpower devices, the isolation, the PN junction terminal processing technology in BCD process,the structure and layout of the high-voltage power devices are designed; According to thefunction and design requirements, the circuit is divided, which includes the band-gapreference, UVLO, oscillator, soft start, driver and OVP; High-voltage devices and low-voltagedevices are separated based on the analysis and calculation of each module; Finally, after thekey modules and the whole application circuit are simulated by Spectre, the layout is designed,and the verification of DRC and LVS are successful.The simulation results show that the indexes of designed controller reach the expectedgoal. The normal operating voltage of the chip is9~28V, and it can be applied in mobilephone, PDA, the charger and the adapter of MP3, PC, the standby power equipment of colorTV and monitor.