Digital dead-time control for an integrated tri-mode buck-boost DC-DC converter

摘要

Traditional fixed dead-time driving strategy can lead to unwanted body-diode conduction or momentary cross-conduction. Since the optimum dead-time varies with the load current, it is important to continuously adjust the dead-time on a cycle by cycle basis. The turning on and off of the switching node also require different dead-times. This paper introduces a digital continuous dead-time correction circuit that can adjust the optimum timing for both the rising and falling edges of the output switching waveform for an integrated non-inverting tri-mode DC-DC converter. The converter is designed to operate with a Li-ion battery as the input power supply (2.7 V to 4.2 V) and to provide an output voltage ranging from 1 V to 5 V. An improvement in peak power conversion efficiency of 3% is observed when the output current varies from 0 to 0.5 A with a switching frequency of 1.5 MHz.