Dual 3-phase buck converter for multi-core CPUs power supply in mobile devices

Abstract

The power supply system in mobile application needs to make a tradeoff between large current ability, lower output voltage ripple, fast transient response, good efficiency and component size and so on. The interleaved multi-phase buck topology offers a good solution to this conundrum. In this paper, the relationship between ripple and duty cycle and phase number is established as a ripple cancellation principle. A dual 3-phase buck converter with 2*6 A maximum current ability is designed very suitable for supplying CPUs/GPUs processors. The proposed buck converter is controlled by peak current mode, which contains an automatic phase adjustment module. At last, the design is implemented in a chip fabricated by SMIC 0.18 um process and WLCSP package, with less than 6 mV ripple and above 80% efficiency during load rang up to 4 A.