An Ultralow Cross-Regulation Single-Inductor Multiple-Output (SIMO) Buck Converter Using Reordered Power-Distributive Control

A single-inductor multiple-output (SIMO) buck converter employing reordered power-distributive control (RPDC) is presented to achieve ultralow cross regulation. Adedicated power-distribution controller implements RPDC by adaptively adjusting the switching sequence: when the inductor current is insufficient, the switching period is extended, and when excessive, an end phase in the form of a freewheeling phase is inserted to minimize cross regulation. During large transients, RPDC is activated; aided by transient detection and processing (TDP), the controller prioritizes victim outputs and defers transient outputs to the end phase, thereby further suppressing cross regulation without hurting the transient outputs. The converter, fabricated in a 0.18-$\mu $m BCD process with all power transistors integrated on-chip, demonstrates a measured voltage droop of 188mV and cross regulation of 9mV/A in the worst-case scenario under a 2-A load transient. Without the freewheeling period in the steady state, the converter achieves a peak efficiency of 89.6% at 2.7W.