In this paper, a design of a fully integrated adaptive Power Management Unit (PMU) for self-sustainable sensor is presented. A compact image sensor is implemented to harvest the micro ambient solar energy and extract the relevant information as well. By combining PMU and communication block on the sensor, the PMU could efficiently manage harvested energy from focal plane, then power up the communication block for transmitting the processed image results out of image sensor. The system presents a complete solution for self-powered sensing and communication micro system, which is of great potential for the deployment of self-sustainable smart IoT nodes on a large scale. The proposed PMU is designed with TSMC 0.18 µm CMOS technology. Through the incorporation of a reconfigurable main charge pump and adaptive control strategy, the PMU takes the capability to adjust its topology in response to the variations of light intensity dynamically, which greatly enlarges the input voltage range. By utilizing a cold-start circuit, the PMU is capable of starting up from a 0.08V harvested input voltage without any external kick-off signal. At a light intensity of 8.54kLux, the PMU achieves peak power conversion efficiency of 93.38%. The presented simultaneous energy harvesting and power management approach ensures self-sustainable operation of the entire system.