Each APLL has a post divider which
will provide a VCO post divider frequency calculated in Equation 6, Equation 7, or Equation 8. The final output
frequency is calculated by dividing from the VCO post divider frequency and the
output divide as calculated in Equation 9. For each output,
the output frequency depends on the selected APLL clock source and output divider
value.
Equation 6. APLL1 selected:
fPOST_DIV = fVCO1 / PnAPLL1
Equation 7. APLL2 selected:
fPOST_DIV = fVCO2 / PnAPLL2
Equation 8. APLL3 selected:
fPOST_DIV = fVCO3 / PnAPLL3
Equation 9. OUT[0:15]: fOUTx
= fPOST_DIV / ODOUTx
where
- fPOST_DIV: Output mux
source frequency (APLL1, APLL2 or APLL3 post-divider clock)
- PnAPLL1: APLL1 primary
"P1" or secondary "P2" post-divide value (2 to 7)
- PnAPLL2: APLL2 primary
"P1" post-divide value (2 to 13) or secondary "P2" post-divide value (2 to
3)
- PnAPLL3: APLL3
post-divide value (1 to 7)
- fOUTx: Output clock frequency (x = 0 to 15)
- ODOUTx: OUTx output bypass or divider value. All
outputs have a 12-bit divider with values 1 to (212 - 1). All outputs
except OUT2, OUT3, OUT14, and OUT15 have the option to follow the 12-bit divider
with a 20-bit SYSREF divider that can be used to produce 1-PPS or other
frequencies below 1 Hz when the SYSREF output is set for continuous output.