5.
已知圆\(M:{{x}^{2}}+{{y}^{2}}={{r}^{2}}(r > 0)\)与直线\({{l}_{1}}:x-\sqrt{3}y+6=0\)相切,设点\(A\)为圆上一动点,\(AB\bot x\)轴于\(B\),且动点\(N\)满足\(\overrightarrow{AB}=\sqrt{3}\overrightarrow{NB}\),设动点\(N\)的轨迹为曲线\(C\).
\((1)\)求曲线\(C\)的方程;
\((2)\)若直线\(l\)与直线\({{l}_{1}}\)垂直且与曲线\(C\)交于\(B,D\)两点,求\(\Delta OBD\)面积的最大值.