Datasheet

TI CDCE62002 Control GUI Interface www.ti.com
Step3: Loop Filter Selection and Setup
The Loop Filter section of the GUI can be clicked for a popup window that opens up showing the internal
loop filter fixed configuration as displayed below. The values of the resistors and capacitors and the
charge pump output current of the internal active loop filter are fixed as displayed in the figure below. The
values are optimized for a 30.72MHz PFD frequency.
Figure 5. Loop Filter, Internal Only
Alternately, the loop filter can be configured to take external components with preselected charge pump
current and high pass filter component. To use External filter, an external loop filter setting from the drop
down menu with the desired charge pump current R3C3 values and only a single filter needs to be
enabled. Enabling the external preset filters can be achieved by selecting Switch 1,2,3 or 4 on Dip
Switches SW9 and SW10 at the back of the CDCE62002EVM. The external loop filter components (C1,
R2 and C2) for the loop filter are selected by the Dip Switches and the R3 and C3 are internal to the
device.
Step 7: Output Type Selection
The Output buffer section of the GUI for each of the outputs can be clicked for a popup window that opens
up, as displayed below, showing selections on each output clock source selectable between LVPECL (in
which cases the a jumper needs to be installed to enable a 150 Ω termination resistor to ground), LVDS,
LVCMOS (in which case each of the P and N act as two separate LVCMOS outputs.
Figure 6. Output Buffer Configuration (each output)
6 Two/Four Output Low Phase Noise Clock Evaluation Board SCAU034 – June 2009
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