A Multi-Mode Four-Switch Buck-Boost DC/DC Converter

Considering that the output voltage of battery will decline during its use, a four-switch buck-boost converter was proposed, which could provide stable output voltage over a wide voltage range of battery so as to extend the use time of battery and enhance its use efficiency. To improve the efficiency, the converter is designed to operate in multiple modes, which controlled by different strategies that depends upon the difference between output and input voltages as well as the different load conditions. As results, the proposed converter could provide a steady output voltage over the entire fluctuating range of battery voltage. The converter chip was designed in 1.5-mum BCD (Bipolar-CMOS-DMOS) technology and the expectations were well achieved.