In this paper we demonstrate that convective Cahn-Hilliard models, describi
ng phase separation of driven systems (e.g., faceting of growing thermodyna
mically unstable crystal surfaces), exhibit, with the increase of the drivi
ng force, a transition from the usual coarsening regime to a chaotic behavi
or without coarsening via a pattern-forming state characterized by the form
ation of various stationary and traveling periodic structures as well as st
ructures with localized oscillations. Relation of this phenomenon to a. kin
etic roughening of thermodynamically unstable surfaces is discussed.