A 10 W 93.7% peak efficiency load balanced single inductor double output (SIDO) hysteretic buck converter with 0.0063 mV/mA low cross regulation

Abstract

This paper presents a novel Single Inductor Double Output (SIDO) Hysteretic Buck converter which balances one output with respect to the other by continously monitoring the load demands of both outputs and then aligning the outputs such that each output regulates its load with minimal disturbance to the other. Load balancing prioritizes the inductor current delivery in the case of a large load current request. The controller aims to finalize the ongoing regulation of the recent output in a prompt manner and then directs the inductor current to the steep load demand output and afterwards returns to the initial output regulation in an iterative way. In conjunction with iterative duty cycle adjustment of outputs, a frequency counter is utilized to accelerate the iteration process to enhance the transient response further. In addition, a delay locked loop fine tunes the duty cycle further to reduce the steady state cross regulation and also limits the switching frequency spectrum. Consequently, both static cross regulation and transient cross regulation performance are further improved compared to previous SIDO architectures. Post-layout simulation results indicate that this architecture has a static cross regulation of 0.0009 mV/mA and transient cross regulation of 0.0063 mV/mA. This SIDO buck converter outperforms the previous studies with a total power delivery capability by supplying 3A load current at each output and 10 W of total power with a peak efficiency of 93.7%.