In this paper, the problem of robust stability and tracking of saturated control systems for buck DC-DC converters is considered. Linear Matrix Inequalities (LMIs) are used to insert the constraints in the design phase while imposing positivity in the closed-loop state. The control objective is to design a control law for the converter that limit duty ratio between 0 and 1. This will allow the system to switch between two topologies in the continuous conduction mode (CCM), to achieve a tracking reference condition. This has been developed using uncertain saturated control and regional pole placement techniques. The proposed controller is applied to a real DC-DC buck converter through a Hardware-In-the-Loop (HIL) test system. Experimental and simulation results show the effectiveness and the success of the proposed controller in tracking a reference voltage with limiting the duty ratio between 0 and 1. Results also show that the proposed controller performed better than the conventional one.