  The layered perovskite compound NaV_2O_5 exhibits charge ordering (CO) and
spin gap formation which is driven by inter- site Coulomb forces and exchange
dimerisation. Experimentally it was found that the CO transition is rapidly
reduced by doping. Charge ordering in NaV_2O_5 has a quasi 1D character due to
inter- ladder frustration in the Trellis lattice. Based on an extended
pseudospin (T=1) approach for hole doped NaV_2O_5 ladders we construct an Ising
like model that explains qualitatively the destruction of the CO phase as
function of hole doping \delta and show how the CO parameter depends on \delta
and the ratio of Coulomb and hopping energies.
