Energy harvesting, also known as power harvesting or ambient power, is the mechanism by which energy is obtained from natural sources (e.g. solar power, piezoelectric) collected and processed for portable, autonomous systems, such as those implemented in wearable systems and wireless sensor networks. Solar energy plays a most important role in renewable energy production, since it is clean, smog-free, sustainable energy and due to rising electricity costs, there is a high demand among utility customers. Electromechanical equivalent circuits can be used for dynamic modeling piezoelectric devices. Piezoelectric materials transform mechanical strain into electric charge or voltage through the direct piezoelectric effect during vibration energy harvesting. It can be implemented to convert walking movement from the person body to electrical energy. The converter regulates the flow of power from the piezoelectric part to the preferred electronic load. Investigation of the converter in irregular current conduction mode is an expression for duty cycle power associations. In this paper, the design and analysis of DC-DC buck converter has been carried out for renewable energy and low power applications. The application sensors are tested with Mock temperature sensor, Motion sensor and also using CMOS temperature sensor for low power applications.