| DC-DC switching power supply with high conversion efficiency was widely used in the fields of portable electronics, computer, communications and automotive electronics and so on. With the expanding of its application areas, it is required that switching power supply has a small size, low power consumption, high reliability, electromagnetic compatibility and modular features.In this paper, a current-control mode of the Buck-type PWM DC-DC single-chip switching power supply, which use the CSMC 0.6μm BiCMOS process was analysed and designed. Firstly, the basic principles of switching power supplies and classification were introduced and were compared with the linear regulator, capacitive and inductive switching power supply with their own characteristics.Then the inductive switching power supply topology, modulation mode, control methods and work mode were highlighted. Secondly, the stability and conversion of Buck-type PWM switching power supply efficiency were analyzed. On this basis, the analysis and design of the bias circuit, bandgap reference, over-temperature protection, output detection, undervoltage lockout, current sampling, oscillator, slope compensation, PWM comparator, error amplifier and logical drives were completed. Finally, upon the completion of circuit design, based on the use of Synopsys's HSPICE software, the module circuit simulation was excuted. The simulation result revealed that the variation of the reference voltage was about 3mV with the temperature range from-40℃to 125℃. The typical output frequency of the oscillator was 1MHz. The maximum delay of the PWM comparator was less than 50ns. The gain of the error amplifier reached 72dB. Other modules also completed their function. The whole design meets the design theory of PWM type DC-DC converter, providing a reference for the future design of superior Switching Power Converter.
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