SNAS750B November 2020 – March 2021 LMK5C33216
PRODUCTION DATA
The following equations provide the APLL and DLL frequency relationships required to achieve closed-loop operation. The TICS Pro programming software can be used to generate valid divider settings based on the desired frequency plan.
Note that any divider in the following equations refer to the actual divide value (or range) and not its programmable register value.
When DPLL operation is enabled, the calculated DPLL frequency and APLL frequency must be nominally the same. It may not be possible for the APLL frequency to operate at the exact DPLL frequency when the APLL N divider 40-bit fixed denominator is selected, however the DPLL adjustments to the paired APLL will correct to the actual clock output frequency desired.
When the APLL operates independent of its paired DPLL, which tracks a reference cascaded from another APLL, it is advisable to select the programmable 24-bit fractional denominator to ensure that clock output frequencies from the cascaded APLL will have 0-ppm frequency error relative to the source PLL.
When using ZDM (zero delay mode) for a PLL, the clock output divider must be accounted for in the VCO frequency calculations.