what $A$ makes $X$ in $\dot{X}=-AX$ converge?

Question

Suppose that $X,A$ are all $n\times n$ matrix, $X$ is variable and $A$ is constant. We have a differential equation $\dot{X}=-AX$, then my question: what conditions should $A$ satisfies to make $X$ converge to $0_{n\times n}$? What are the related theories?

Thanks.