A 92%-Efficiency Battery Powered Hybrid DC-DC Converter for IoT Applications

A two-stage hybrid power management unit (PMU) is presented with a highly-efficient novel ON-OFF LDO as the second stage and uses a switched-capacitor dc-dc divider as the first stage. The design targets IoT applications that operate across a wide range of load from sub-microwatt to 100's of microwatts. The first stage provides a step-down using selectable sizing of its switches to improve efficiency to >95% across the target range of load current. The output voltage that is divided from the first stage is then regulated using the proposed ON-OFF LDO with a dropout voltage of <; 30mV. The hybrid architecture regulates a 1.3V input to 0.4V and achieves a power efficiency of >80% for load ranges 1μ-240μA . The design is fabricated in 28-nm CMOS technology.