Design Of A Low-power Boost DC/DC Converter With Selectable Current Limit

With the development of the portable electronic production, the demand of low-power, high-efficiency and small DC/DC converter has been enhanced. Therefore, the DC/DC converter has a very high prospective in the markets, whith a good future. Consequently, the research about the control circuits in DC/DC power supply with low-power, high-efficiency for driving LCDs has important significance.This thesis firstly discusses the basic principle of the boost DC/DC converter which focused on the current feedback mode and pulse frequency modulation. According to the strict request for the bulk, cost and power, the architecture of the system is designed. In the circuit design chapter, the operation principle of the whole-chip circuit and function of each sub-block circuit are given. Subsequently, detail operation principles of several sub-blocks including bandgap reference, current-sensing circuit as well as PFM control etc, are analyzed. Simulation results with Spectre indicate that the circuit has achieved its function target and the expected electrical characteristics.Then the parameter designs of the external application circuit are detailed presented. And the system simulation of the current limit setting to 125 mA, 250 mA, or 500 mA with Spectre is given.At last, the special structure of internal power MOSFET is given. The chip was taped out with a foreign company Bi-CMOS 0.6 um process, the results of both the simulation and test are achieved its function target of efficiency at the variable loads and the expected electrical characteristics.