A Single-Inductor-Dual-Output Buck/Boost/Buck-Boost Converter for Wearable Devices

This paper presents a single-inductor-multiple-output (SIMO) buck/boost/buck-boost converter for wearable electronic devices.Aiming at high light-load efficiency and low ripple, the converter applies fully asynchronous burst mode control. The circuit enters sleep mode intermittently during light loads, significantly reducing static power consumption. The peak inductor current is fixed, effectively limiting the maximum output ripple. The converter features three conversion modes: buck, boost, and auto-gain buck-boost. DC analysis is conducted to derive expressions for output ripple and maximum load in relation to the peak inductor current. AC stability analysis is performed with small signal perturbation and linearization methods, proving the stability of all three modes. Measured results indicate that the converter achieves a peak efficiency of 91.0% at an output power of 77.5 mW. The maximum output ripple is 27.0 mV, and the overshoot or undershoot during load transients is not observed. Compared with existing converters, it exhibits higher efficiency and lower ripple, along with a fast load transient response, offering a highly efficient power management solution for wearable devices.