With the variations of circuit parameters

the operating state of current mode controlled buck converter by utilizing compensating ramp current can shift between stable period-one region

robust chaos region in continuous conduction mode (CCM) and intermittent chaos region in discontinuous conduction mode (DCM).By establishing the piecewise smooth iterative map with ramp compensation

two borderline equations of the orbit states shifting of current mode controlled buck converter are derived

and the corresponding operating state regions are decided.The simulation results of the parameter space map of buck converter verify the estimated operating state regions by two borderline equations.The estimation of operating state regions for switching converter has practical guideline signification for selection of circuit parameters as well as stability control of chaos.