| Nowadays, switching power supply management ICs are largely used in the computers that dominant in the field of terminal devices, communication equipments and almost all electronic equipments for its outstanding small, light and high-efficiency features, which have become the indispensable power supply mode for the fast growing of today's electronic information industry. For these cases, the program discussed in the paper makes a significant sense.The paper presents a design of a PFM (Pulse Frequency Modulation) step-up DC/DC converter with LDO. Based on 0.6μm CMOS technology of CSMC, the program uses the Cadence EDA tools and will adapt 8-pin TSSOP package. The normal operating temperature of this chip ranges from -30℃to 85℃, the output voltage are 1.8V/3.0V/3.3V, the low quiescent current is 32μA and the maximum efficiency reaches 90%. The chip is ideal for 1 Cell or 2 Cell Alkaline battery and USB applications. For example, MP3s, power source for PDAs, Cameras and VCRs and so on.The paper, first, analyses the basic principles of linear-voltage regulator and presents the electrical characteristics of the circuit system. Second, it briefly introduces the circuit topologies of DC/DC converter and the control modes of switch power supply. And then, based on the above theories, the circuit design and simulation means have been concretely applied in the internal modules of voltage reference, bias circuit, oscillator, error amplifier and drive circuit of the chip and so on. The relevant design indexes are successfully achieved. At last, the whole circuit simulation and layout design are completed. |
