CY7B9910
CY7B9920
Operational Mode Descriptions
shows the device configured as a zero skew clock
buffer. In this mode the 7B9910/9920 is used as the basis for a
low skew clock distribution tree. The outputs are aligned and may
each drive a terminated transmission line to an independent
load. The FB input is tied to any output and the operating
frequency range is selected with the FS pin. The low skew speci-
fication, coupled with the ability to drive terminated transmission
lines (with impedances as low as 50 ohms), enables efficient
printed circuit board design.
shows the CY7B9910/9920 connected in series to
construct a zero skew clock distribution tree between boards.
Cascaded clock buffers accumulates low frequency jitter
because of the non-ideal filtering characteristics of the PLL filter.
Do not connect more than two clock buffers in series.
Figure 3. Board-to-Board Clock Distribution
REF
Z
0
FB
SYSTEM
CLOCK
REF
FS
LOAD
LOAD
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
FB
REF
FS
Z
0
LOAD
Z
0
TEST
Z
0
TEST
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
LOAD
LOAD
Document Number: 38-07135 Rev. *B
Page 9 of 11
CYPRESS [ CYPRESS SEMICONDUCTOR ]
