An Adaptively Controlled 10-Output Reconfigurable Dual-Bus SIMO System With Group Allocator for Diversified Load Condition

Abstract

Portable electronic devices require multiple supply voltages with relatively large differences in load currents, causing serious regulation, EMI, and efficiency problems when adopting a single-inductor multiple-output (SIMO) dc-dc converter. To resolve these issues, this paper presents a reconfigurable SIMO system with ten-output having two buses, one for heavy-load and one for light-load outputs. The converter maintains the load current condition so that each bus is well balanced even when the load currents are diversified by using the proposed group allocator, which properly assigns a bus for each output depending on its load current. Due to this load balancing function, regulation issues that could occur under diversified load conditions are resolved, and high efficiency is achieved over a wide load current range. The test chip was fabricated in 1P4M 0.18 mu m CMOS process. The system has ten independently regulated outputs with an output voltage ripples below 25 mV, and greater than 81% efficiency is achieved across a wide load range (0-300 mA).