Power electronic circuits exhibit nonlinear dynamical behaviour due to their inherent inhomogeneity and switching. Among power electronic converters, the DC/DC buck converter is studied with constant-frequency pulse-width modulation feedback control in continuous conduction mode. Phase-space and time-domain plots for several periodic and chaotic orbits are presented. The bifurcation diagram is studied together with periodic orbits and chaotic behaviour of the circuit. Several simulation methods including exact solution and simulation in an EMTP-type program are used and the importance of accurate modeling is justified. Finally, a method for computation of Lyapunov exponents in discontinuous systems is reviewed and implemented.