This report introduced design process of the DC-to-DC step-down converter. In the report analytical solution of the problem, design process, simulation details, stress tests and experiments were discussed. As it can be seen from the results of the experiments, controller fulfill given tasks and shows good results for given specifications. In addition, controller and the circuit is able to perform under extreme and dynamic conditions, i.e. when the power increased dramatically or reference changed. Moreover, some additions such as ramp reference voltage introduced in order to avoid overshooting. Finally, I feel very happy with obtained results.