XP2 Datasheet, PDF (15/92 Pages) Lattice Semiconductor – LatticeXP2 Family Data Sheet

Lattice Semiconductor
Architecture
LatticeXP2 Family Data Sheet
Primary Clock Routing
The clock routing structure in LatticeXP2 devices consists of a network of eight primary clock lines (CLK0 through
CLK7) per quadrant. The primary clocks of each quadrant are generated from muxes located in the center of the
device. All the clock sources are connected to these muxes. Figure 2-9 shows the clock routing for one quadrant.
Each quadrant mux is identical. If desired, any clock can be routed globally.
Figure 2-9. Per Quadrant Primary Clock Selection
Primary Clock Sources: PLLs + CLKDIVs + PIOs + Routing
30:1
30:1
30:1
30:1
30:1
30:1
29:1
29:1
CLK0
CLK1
CLK2
DCS
CLK3
CLK4
CLK5
CLK6
8 Primary Clocks (CLK0 to CLK7) per Quadrant
29:1
29:1
DCS
CLK7
Dynamic Clock Select (DCS)
The DCS is a smart multiplexer function available in the primary clock routing. It switches between two independent
input clock sources without any glitches or runt pulses. This is achieved irrespective of when the select signal is
toggled. There are two DCS blocks per quadrant; in total, eight DCS blocks per device. The inputs to the DCS block
come from the center muxes. The output of the DCS is connected to primary clocks CLK6 and CLK7 (see Figure 2-
9).
Figure 2-10 shows the timing waveforms of the default DCS operating mode. The DCS block can be programmed
to other modes. For more information on the DCS, please see TN1126, LatticeXP2 sysCLOCK PLL Design and
Usage Guide.
Figure 2-10. DCS Waveforms
CLK0
CLK1
SEL
DCSOUT
Secondary Clock/Control Routing
Secondary clocks in the LatticeXP2 devices are region-based resources. The benefit of region-based resources is
the relatively low injection delay and skew within the region, as compared to primary clocks. EBR rows, DSP rows
and a special vertical routing channel bound the secondary clock regions. This special vertical routing channel
aligns with either the left edge of the center DSP block in the DSP row or the center of the DSP row. Figure 2-11
shows this special vertical routing channel and the eight secondary clock regions for the LatticeXP2-40.
2-12