A Single-Inductor Triple-Output Buck-Boost Converter with Output Ripple Control for Wearable Devices.

This paper presents a single-inductor tripleoutput (SITO) buck-boost converter for wearable devices. It converts a 2.8V to 4.8V Li-ion battery voltage to three regulated output voltages: 1.2 V, 1.8V, and 3.3V for different back-end circuits, such as digital circuits and analog circuits. The converter operates at discontinuous conduction mode (DCM) and regulates the output using pulse-skip modulation (PSM) to reduce cross-regulation. Furthermore, the converter includes an adaptive on-time (AOT) generator to improve the output power range at low input voltage and control the maximum output voltage ripple under different inputs. Furthermore, three selftracking zero current detectors (ST-ZCD) provide appropriate off-time periods for power MOSFETs to reduce the reverse inductor current. The measurement results show that the proposed SITO buck-boost converter achieves a maximum peak power conversion efficiency of 75.8% under 315mW output power. In addition, the peak inductor current is well controlled under different input voltages.