Abstarct: Portable electronic devices often require a regulated dc voltage that is within the range of fully charged to semi-discharged batteries. Due to highly variable nature of batteries voltage (e.g., 2.7 V for semi-discharged to 4 V for fully-charged) power supply of these devices need to work both in higher and lower voltage than output. The optimal solution to this demand is a high efficiency and low cost non-inverting buck-boost converter which can provide programmable constant output voltage from a wide variable range input supply. DC-DC converter feedback loops are typically designed conservatively so that the closed loop regulation and stability margins are maintained over expected range of operating conditions and they may lose the performance by using this kind of structures. This thesis presents an approach to adaptive control and system identification of this converter in the presence of large signal changes, uncertainty of converter’s component and effects of imperfect modeling. The proposed approach is capable of maintaining a high performance response without the in-stability issue of large signal disturbances or dynamic change of converter. In the case that the plant parameters are uncertain, a digital adaptive controller baxsed on system identification and minimum degree pole placement is also proposed. To verify the validity of the proposed digital controller, an experimental set-up is built for non-inverting buck boost converter and the fully digital adaptive control algorithm is implemented by a digital micro-controller ATxmega128A1.