This paper deals with the control and observation of DC output power electronic converters. In order to propose a general approach, a unified modeling methodology is first introduced. A switched state feedback control law using perturbed measurements and a full-order observer are then designed separately based on LMI conditions. The observer is used to compute the control law while the input and output voltages are measured, as well as perturbations. The resulting conditions ensure the exponential convergence of the reconstruction error towards zero. Then, showing the input-to-state stability (ISS) property of the system, we prove that the estimated state can be used instead to asymptotically stabilize the system. Therefore, the control scheme satisfies the separation principle property. Results are illustrated by simulations in PLECS with a noninverting Buck-Boost converter (DC-DC) and a Half-Bridge Boost PFC converter (AC-DC).