Using the following configuration:
Register 0x0109 bit 2 = 0: PLL1 Feedback Divider Source; 0 selects the PLL2 feedback divider
Register 0x010A bit 3 = 1 VCXO_CTRL control voltage goes to VCC/2.
R1 = 3; N1 = 512; Ra=125;
VCXO = 10*(R1*N1/Ra) = 122.88MHz
PLL 1 PFD input frequency is 80KHz
Does the loop bandwidth or charge pump current need to be changed?