Capacitors for 16MHz XTAL

[Deimantas]

What capacitors would you recomend for this 16MHz Quartz http://www.jauch.de/ablage/med_00000848_1411137106_JXS32-180914.pdf to ensure 40ppm frequency tolerance for nrf51822? Is it correct to use 12pF?

[FormerMember]

The formula for finding the values of the capacitors C1 and C2 to be used with a crystal is:

C1 = C2 = 2*C_l - C_pcb - C_pin,

where

C_l: Load capacitance of the crystal

C_pcb + C_pin is approximately 4 pF.

The above formula can be found in the whitepaper " Crystal Oscillator Design Considerations" and chapter 3.6.1 in the nRF51822 Product Specification.

The maximum value of C_l depends on the crystal, see the nRF51822 Product Specification, chapter 8.1.2.

In your case, the standard value for C_l is 12 pF, it means that C1 = C2 = 20 pF.

[Deimantas]

Thanks. ;)