The DC micro grids consist of multiple power electronic converter units interconnected in a network with sources and loads. The constant power loads (CPLs) have negative impedance effects, which may cause instability in a DC micro grid. This paper develops a framework that can analyze the DC micro grid stability for a given range of constant power loads (CPLs). The power systems in the more electric aircraft, navy ships, or automotive is composed of generation units and multiple ac/dc loads interconnected together through filters and power converters. The effectiveness and non-conservativeness of the proposed framework are demonstrated using simulation examples.