R
Virtex™-II Platform FPGAs: Detailed Description
Figure 12 provides examples illustrating the use of the SSTL2_I_DCI, SSTL2_II_DCI, SSTL3_I_DCI, and SSTL3_II_DCI I/O
standards. For a complete list, see the Virtex-II User Guide.
SSTL2_I
SSTL2_II
SSTL3_I
SSTL3_II
V
/2
V
/2
CCO
CCO
V
/2
V
/2
V
/2
V
/2
CCO
CCO
CCO
CCO
R
R
R
R
R
R
Conventional
Z
0
Z
0
Z
Z
0
0
R/2
R/2
R/2
R/2
V
/2
CCO
V
V
/2
CCO
V
V
/2
CCO
CCO
CCO
V
/2
CCO
(1)
DCI Transmit
Conventional
Receive
(1)
(1)
25Ω
25Ω
(1)
25Ω
R
R
R
2R
2R
2R
25Ω
R
Z
Z
0
0
Z
0
Z
0
2R
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
V
V
V
V
V
V
CCO/2
CCO
2R
CCO/2
CCO
2R
CCO
2R
CCO
2R
Conventional
Transmit
DCI Receive
R
R
Z
Z
Z
Z
0
0
0
0
R/2
R/2
R/2
R/2
2R
2R
2R
2R
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
V
V
V
(1)
2R
V
V
CCO
V
CCO
CCO
CCO
CCO
CCO
(1)
(1)
(1)
2R
25Ω
2R
25Ω
25Ω
25Ω
2R
2R
2R
DCI Transmit
DCI Receive
Z
0
Z
Z
Z
0
0
0
2R
2R
2R
2R
2R
2R
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
V
V
(1)
V
V
CCO
CCO
CCO
CCO
(1)
25Ω
25Ω
2R
2R
2R
2R
Z
Z
0
0
Bidirectional
N/A
N/A
2R
2R
2R
2R
(1)
(1)
25Ω
25Ω
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Virtex-II DCI
Reference
Resistor
VRN = VRP = R = Z
VRN = VRP = R = Z
VRN = VRP = R = Z
VRN = VRP = R = Z
0
0
0
0
Recommended
50 Ω
50 Ω
50 Ω
50 Ω
(2)
Z
0
Notes:
1. The SSTL-compatible 25Ω series resistor is accounted for in the DCI buffer, and it is not DCI controlled.
2. Z is the recommended PCB trace impedance.
DS031_65b_112502
0
Figure 12: SSTL DCI Usage Examples
DS031-2 (v3.0) August 1, 2003
Product Specification
www.xilinx.com
1-800-255-7778
Module 2 of 4
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