We consider the asymptotics of the coefficients of  generating function $y(x)$, 
which is defined by the implicit function $y= F(x,y)$.

Let $F(x,y)$ be a rational function in $x$ and $y$, such that $F(x,y)$ has non-negative coefficients of development in $x$ and $y$. Further $F(x,y)$ is not a linear function of $y$. Can we conculde that $[x^n]y(x)\sim \rho^{-n} n^{-\frac{3}{2}}$? 

If not, what kind of additional condition do we need to prove such asymptotics?

It seems that it can be derived from singularity analysis. One reference could be 
Flajolet and Sedgewick's Book  "Analytic Combinatorics". However the proof in there is rather obscure to me. 

I think that we still need to additional condition to make that conclusion,  such as there exist $r>0$ and $s>0$ satisfying
\begin{equation}
F(r,s)=s, F_x(r,s)=1.
\end{equation}


Any reference about this topic would be appreciated. Thank you in advance.