8
ECP5 and ECP5-5G sysCLOCK
PLL/DLL Design and Usage Guide
There is one PCSCLKDI
V
per SERDES Channel on the bottom of the device where the SERDES blocks are
located. The clock outputs of the PCSCLKDI
V
(CDI
V
1, CDI
V
X) are delay and phase matched to each other and
has a run-time selectable divider value. The PCSCLKDI
V
clock input sources are:
• Up to four TX Channel Clocks
• Up to four RX Channel Clocks
• Clock from Routing
Figure 6. PCSCLKDIV Connection Diagram
The output PCS channel clocks route directly to the input of the PCSCLKDI
V
without requiring the use of a primary
clock. The CDI
V
1 and CDI
V
X outputs route directly to the primary clock routing. Its function is to do bus widening /
narrowing circuits in the FPGA fabric to reduce the fabric frequency. The PCSCLKDI
V
is not suitable for DDR I/O
interfaces (ECLK to SCLK domain crossing).
Figure 7. Logical Functional Timing of PCSCLKDIV Block
Clock from ro
u
ting
4 TX Channel Clocks
4 RX Channel Clocks
RST
SEL[2:0]
PCSCLKDIV
/1,/2,/4,/5,/
8
or /10
/1
Primary Clocks
Mid MUX
CLKI
RST
CDIV_1
CDIV_2
CDIV_4
CDIV_5
CDIV_
8
CDIV_10
De-asserted RST
is registered
Asserted RST
is asynchronized
Delayed o
u
tp
u
t
clocks start
toggling