3.3.3. xN Clock Lines
The master CGB drives the x6 clock lines and the x6 clock lines drive the xN clock lines. There are two xN clock lines: xN Up and xN Down. xN Up clock lines route the clocks to transceiver banks located above the master CGB and xN Down clock lines route the clocks to transceiver banks located below the master CGB. The xN clock lines can be used in both bonded and non-bonded configurations. For bonded configurations, the low speed parallel clock output of the master CGB is used, and the local CGB within each channel is bypassed. For non-bonded configurations, the master CGB provides a high speed serial clock output to each channel.
The maximum channel span of a xN clock network is two transceiver banks above and two transceiver banks below the bank that contains the driving PLL and the master CGB. A maximum of 30 channels can be used in a single bonded or non-bonded xN group.
The maximum data rate supported by the xN clock network while driving channels in either the bonded or non-bonded mode depends on the voltage used to drive the transceiver banks.