Cumulative Charge Balanced Single-Inductor Dual-Output Converter for Improved Transient and Cross Regulation

Increasing complexity and applications in highly integrated systems on chips (SoCs) for consumer electronics, automobile infotainments, wearables etc. the power management unit (PMU) is required to provide several power supplies efficiently for individual applications. Such multiple rails to cater to high performance in the applications involve high form factor and BOM size on the chip. This paper proposes a Single-Inductor Dual-Output (SIDO) Boost converter topology with an application-specific switching scheme induced with a novel control methodology to power two step-up (boost) outputs 6.3V and 5.0V from a Li-ion Battery (2.7V – 4.5V) input. The target application is a mid-power wearable application (6W) with very high load transients. The novel control scheme almost eliminates the cross-regulation amongst the outputs across all load transitions. Results show a cross-regulation of 0.06 mV/mA at VOUT2 when VOUT1 is stepped up from low to rated load and 0.06 mV/mA at VOUT1 when VOUT2 is stepped up from low to rated load. Even with simultaneous maximum load transitions at both the outputs the droops in VOUT1 and VOUT2 is 0.168 mV/mA.