Digital Low Power Mode Control Technique for High-Frequency Synchronous DC-DC Buck Converters

This paper presents a low power mode control technique for digitally controlled synchronous buck converters optimized for the heavy load regulation. The proposed control mode achieves compact area and low complexity thanks to an efficient logic partitioning and reuse of the digital controller. The inductor peak current is controlled with a predictive algorithm that does not require current sensing. A prototype of a digitally controlled synchronous 5—0.9 V, 1.5 A buck DC-DC converter that embeds the low power control technique is implemented. A custom IC in a 28nm CMOS process has been designed for the digital controller and the gate drivers. Experimental results indicate that the high efficiency range is extended, obtaining an efficiency improvement up to 43% at light load.