EP1SGX10DF672C6 Datasheet, PDF (135/272 Pages) Altera Corporation – Section I. Stratix GX Device Family Data Sheet

Stratix GX Architecture
These clocks are organized into a hierarchical clock structure that allows
for up to 22 clocks per device region with low skew and delay. This
hierarchical clocking scheme provides up to 40 unique clock domains
within EP1SGX10 and EP1SGX25 devices, and 48 unique clock domains
within EP1SGX40 devices.
There are 12 dedicated clock pins (CLK[15..12], and CLK[7..0]) to
drive either the global or regional clock networks. Three clock pins drive
the top, bottom, and left side of the device. Enhanced and fast PLL
outputs as well as an I/O interface can also drive these global and
regional clock networks.
There are up to 20 recovered clocks (rxclkout[20..0]) and up to
5 transmitter clock outputs (coreclk_out) which can drive any of the
global clock networks (CLK[15..0]), as shown in Figure 4–41.
Global Clock Network
These clocks drive throughout the entire device, feeding all device
quadrants. The global clock networks can be used as clock sources for all
resources within the device IOEs, LEs, DSP blocks, and all memory
blocks. These resources can also be used for control signals, such as clock
enables and synchronous or asynchronous clears fed from the external
pin. The global clock networks can also be driven by internal logic for
internally generated global clocks and asynchronous clears, clock
enables, or other control signals with large fanout. Figure 4–41 shows the
12 dedicated CLK pins and the transceiver clocks driving global clock
networks.
Altera Corporation
February 2005
4–69
Stratix GX Device Handbook, Volume 1