The crystal ratings are the maximum ratings which means we recommend a 500uW crystal to make sure power dissipation does not exceed the drive level of the crystal and 12pF is only a recommended value which satisfies the drive level equation.
hi Sananya .
so a 100uW/9pF crystal should work fine with thre CY7C65621/31 items ?
Please use the equations. Our recommended values are only a starting point to help arrive close to the crystal that will satisfy both power dissipation and load capacitance equations. The power equation will also take into account ESR of the crystal which could be different for crystals with same drive-level and capacitance.