Design of a Low Power, High Performance BICMOS Current-limiting Circuit for DC-DC Converter Application

Abstract

A low power, high performance current-limiting circuit implemented in 0.6um BICMOS process, which has been successfully applied to the chip of high e-ciency, wide input voltage range DC-DC boost switch power management chip, is presented. The circuit as the core sub-block of the chip consists of current-limiting comparator, soft starting and slop compensation. The dynamic bias and slop compensation technology in current-limiting comparator is adopted to improve the performance and to reduce power consume. In this paper, the deign methodology and process of the circuit is analyzed in detail. The simulation and test results based HSPICE show: under the power supply of 3.3V, the circuit has the gain of 117dB and low quiescent current of 15UA. DOI: 10.2529/PIERS060817034009 With the rapid development of the integrated circuit technology, the requirement of low power consumption, small volume, low cost for portable and powered equipment such as MP3, PDA and digital camera can be satisfled impossibly, meanwhile, the new functions belonging to the \energy hunger and thirst type are increasing with day, so it is key issue in this fleld how to integrate these new functions in smaller volume and to prolong the service time of battery-operated equipments. At present, the switch-mode DC-DC converters have been widely used in power supply systems and are becoming a common building block in modern VLSI systems, which are taking place of LDO and will be the best solution because of its high e-ciency. Therefore, it is meaningful and better market prospect to research the power management IC of high e-ciency, low power. Figure 1 illustrates a simplifled boost dc-dc converter's functional block diagram. Its main function is to convert input dc voltage to higher output dc voltage with minimum power loss. The converter is composed of a power stage and feedback control circuits. VS is a battery voltage, which supplies input dc voltage, and is the boosted output dc voltage. The inductor L, diode D1, and capacitor C are ofi-chip components. Resistors R1 and R2 sense the output voltage and generate the scaled output voltage to the error amplifler. RLOAD is the load of the dc-dc converter.