Research And Develop Of Digital Controlled Switching Power Supply

With the development of science, the switching power supply has become an ideal power source for people to use. The digital controlled switching power supplies have the advantages of high degree of intelligence, good accuracy, easy operation, high stability, high conversion efficiency and flexible output adjustment, and the replacement of the traditional analog power supply is the future development trend .Thus, the researches on the digital controlled switching power supply applied in precise conditions are very necessary.The overall design method can be obtained by comparing and analyzing the module program of the digital controlled switching power supply. The digital controlled switching power supply consists of auxiliary power supply circuit, the smallest single-chip system, the digital-analog conversion module, the key circuit module, digital tube display module and regulated output circuit. The module hardware circuits of the controlled circuits are designed and specific analysis and calculation is made on the selection of related devices for power supply modules. The circuit component parameters of the Boost converter are designed, the design consists of the energy storage inductor, the output voltage sampling resistor, the switch,the output diode, the output capacitor, the compensation network, the slope compensation and the protection circuit. The selection of the power field effect transistor MOSFET is researched.The main program and related subroutine are programmed by using the assembly language and the programs consist of the keyboard scanning subroutine, the preset value subroutine, the D / A conversion subroutine, the A / D conversion subroutine, the calibration subroutine and the host computer communication subroutine. A digital controlled switching power supply controlled by STC89C52 is made through the joint debugging of software and hardware. The system is programmed by the single-chip digital signal output, the analog quantity is output via the D / A converter (DA0832), and then amplified by the op amp, the obtained voltage can be used as the reference voltage of the pulse width modulator, and its output voltage can be changed with the change of the preset value. The output voltage can be set through the keyboard, the step level can be set to 0.1V and the actual output voltage can be displayed by the digital tube.The real-time monitoring of the switching power supply can be realized by single-chip system, the output voltage is converted through the A/D converter chip, the real-time analog parameter is converted into digital parameter and then processed by the micro-controller, and the obtained parameter is sent to the digital tube for displaying. The functions of the error correction, the fault self diagnosis and the over-current over-voltage protection are considered in the implementation process and it has higher practicality.Combining with the obtained parameter design method, a digital controlled switching power supply prototype is made, the joint debugging of software and hardware is made, and the experimental results show that the system have the features of stable output voltage, good load regulation rate, adaptable environment and the output voltage can be set in the 12V ?18V range. The adjustable output voltage accuracy has been obtained and the real-time display function can be realized. The design requirements have been met.