芯片手册要求用负载电容为20pF的无源晶振，可否用9pF的呢？

答：不建议。

解释如下：

It is highly recommended to use the 20pF load capacitance, although 9pF may be OK. Using 9pF load capacitance will result in an oscillation frequency that has some frequency error; it will be faster than anticipated.

晶诺威科技强烈建议使用负载电容为20pF的无源晶振。尽管负载电容为9pF的晶振或许也可以使用，但是有可能导致振荡频率频率偏移加大，具体表现为频率升高，容易引发频率错误。