Low Input Power Management Circuit for Ambient Energy Harvesting

Due to the input low power (less than 1mW), the Internet of Things (IoT) nodes cannot be powered directly by harvesting energy from the ambient. In most cases, the output DC voltage is so small that it can't drive the load circuit such as microcontroller unit (MCU) whose threshold voltage should be at least larger than 1.8V. In this paper, we propose a power management circuit based on BQ25504 chip, which has very low start-up voltage of only 330 mV and can work continuously at voltages as 80 mV after start-up. Through designing the DC-DC circuit, the output voltage of the chip can be in the range of 3.5~4.2 V so that the RF energy in the ambient can be harvested to power the proposed low-power IoT node.