Dear Zhao,
please refer to the Table 7. in the P3S0200 datasheet. The VCC voltage sets the VIH and VIL levels for the input pins. If VCC=3.3V, than minimum voltage required on the input pins, to be recognized as logic high it 0.46*VCC=0.46*3.3V=1.518V. You can use the 1.8V for the input pins. The 1.8V will be recognized as logic high.
With Best Regards,
Jozef
