根据DATASHEET,该脚的描述如下,pin 5, Vstr,
This pin connects directly to the rectified AC line voltage source. At start up
the internal switch supplies internal bias and charges an external storage
capacitor placed between the Vcc pin and ground. Once the Vcc reaches
12V, the internal switch is opened.
看明白了吗?该脚是直接接整流后的电源的。270V不是高了。该脚能承受最高650V电压!