  An isotropic and homogeneous cosmological model with a source of dark energy
is studied. That source is simulated with a viscous relativistic fluid with
minimal causal correction. In this model the restrictions on the parameters
coming from the following conditions are analized: a) energy density without
singularities along time, b) scale factor increasing with time, c) universe
accelerated at present time, d) state equation for dark energy with "w" bounded
and close to -1. It is found that those conditions are satified for the
following two cases. i) When the transport coefficient ({\tau}_{{\Pi}}),
associated to the causal correction, is negative, with the aditional
restriction {\zeta}|{\tau}_{{\Pi}}|>2/3, where {\zeta} is the relativistic bulk
viscosity coefficient. The state equation is in the "phantom" energy sector.
ii) For {\tau}_{{\Pi}} positive, in the "k-essence" sector. It is performed an
exact calculation for the case where the equation of state is constant, finding
that option (ii) is favored in relation to (i), because in (ii) the entropy is
always increasing, while this does no happen in (i).
