31.8 A 11.7W 9mV/A-Cross-Regulation Single-Inductor Triple-Output Buck Converter Using Unordered Power-Distributive Control for a 2A Load Transient

Single-inductor multiple-output (SIMO) converters, capable of providing multiple outputs from just one inductor, are highly favorable in cost- and size-constrained applications such as mobile devices. However, they inherently face cross regulation issues, especially during large load transients. Time-multiplexing control (TMC) combined with a digital non-linear technique is adopted in [1] to address these issues by separating the charging of each output. Nevertheless, the converter needs to operate in discontinuous conduction mode (DCM), resulting in large output ripples and low power delivery. Hence, ordered power-distributive control (OPDC) is widely adopted in SIMO converters [2–5] to reduce output ripples and enhance power delivery. However, it aggravates cross-regulation since all outputs draw energy from the inductor sequentially within one cycle [2]. A cross-talk reduction error amplifier (CREA) is proposed in [3] to reduce cross regulation by adaptively correcting the inductor current level for each victim output, but the correction accuracy is influenced by PVT variations. In [4], charge control with a freewheeling period is proposed to precisely regulate per-cycle charge of the outputs to effectively mitigate cross regulation, while the efficiency is significantly compromised due to the power loss of the freewheeling period. In [5], ripple-based control offers rapid responses. However, its variable switching frequency during transients adversely affect victim outputs. It is worth noting that the cross-regulation performance of these converters [1–5] was measured with load steps up to only 300mA. In scenarios with larger load steps, such as 2A, performance may deteriorate significantly as the charging or discharging durations for the victim outputs are changed more drastically.