有VCAP引脚的芯片手册上会对VCAP引脚做说明,“A device I/O pin may be configured as the LDO voltage
output, identified as the VCAP pin. Although not required, an external low-ESR capacitor may be connected to the VCAP pin for additional regulator stability”。
故可知道,实际上VCAP引脚是芯片内部的稳压电路(即LDO,进行电压转换)的电压输出引脚,VCAP引脚建议外接电容,这相当于外接去耦电容,能改善VCAP引脚电压波纹。