5
ICS91309
0093H—12/09/08
Output to Output Skew
The skew between CLKOUT and the CLKA/B outputs is not dynamically adjusted by the PLL. Since CLKOUT is one
of the inputs to the PLL, zero phase difference is maintained from REF to CLKOUT. If all outputs are equally loaded,
zero phase difference will maintained from REF to all outputs.
If applications requiring zero output-output skew, all the outputs must equally loaded.
If the CLKA/B outputs are less loaded than CLKOUT, CLKA/B outputs will lead it; and if the CLKA/B is more loaded
than CLKOUT, CLKA/B will lag the CLKOUT.
Since the CLKOUT and the CLKA/B outputs are identical, they all start at the same time, but different loads cause them
to have different rise times and different times crossing the measurement thresholds.
REF input and
all outputs
loaded
Equally
REF input and CLKA/B
outputs loaded equally, with
CLKOUT loaded More.
REF input and CLKA/B
outputs loaded equally, with
CLKOUT loaded Less.
Timing diagrams with different loading configurations
