Hi, there,
I have a question about HFXO load capacitors and LFXO load capacitors.
Each load capacitors of nRF52840-DK are like below.
And i checked BOM file to find out load capacitance of each xtals.
XTAL SMD 2016, 32MHz, Cl=8pF, Tol: ±10ppm, Stab: ±15ppm
XTAL SMD 2012, 32.768kHz, 9pF, ±20ppm
As you know, load capacitor equation is like below.
C1 = C2 = C_L * 2 - (Input capacitance XC1 and XC2 in case of HFXO)
C17 = C18 = C_L * 2 - (Input capacitance on XL1 and XL2 pads in case of LFXO)
So, if i calculate these values based on document,
Input capacitor of HFXO C1=C2=8*2-3pF=13pF
input capacitor of LFXO C17=C18=9*2-4pF=14pF
Input capacitors of nRF52840-DK and values of above are different.
Could anybody answer why this is different?
Thank you.
