Controlled Impedance Driver With Half Impedance (Source Termination); Input Termination To Vcco (Single Termination) - Xilinx Virtex-5 FPGA User Manual

Controlled Impedance Driver with Half Impedance (Source Termination)

DCI also provides drivers with one half of the impedance of the reference resistors. This
doubling of the reference resistor value reduces the static power consumption through
these resistors by a factor of half. The DCI I/O standards supporting controlled impedance
drivers with half-impedance are LVDCI_DV2_15, LVDCI_DV2_18, and LVDCI_DV2_25.
Figure 6-7
reference resistors R must be 2 × Z
X-Ref Target - Figure 6-7
Input Termination to V
Some I/O standards require an input termination to V
X-Ref Target - Figure 6-8
DCI can also provide input termination to V
resistance is set by the reference resistors. Both GTL and HSTL standards are controlled by
50 Ω reference resistors. The DCI I/O standards supporting single termination are:
GTL_DCI, GTLP_DCI, HSTL_III_DCI, HSTL_III_DCI_18, HSTL_IV_DCI, and
HSTL_IV_DCI_18.
Virtex-5 FPGA User Guide
UG190 (v5.0) June 19, 2009
illustrates a controlled driver with half impedance inside a Virtex-5 device. The
0
R/2
Virtex-5 DCI
Figure 6-7: Controlled Impedance Driver with Half Impedance
(Single Termination)
CCO
R
Z
0
Figure 6-8: Input Termination to V
www.xilinx.com
SelectIO Resources General Guidelines
in order to match the impedance of Z
IOB
Z
0
UG190_6_05_021206
(see
CCO
V
CCO
IOB
V
REF
Virtex-5 FPGA
UG190_c6_06_022609
without DCI
CCO
using single termination. The termination
CCO
.
0
Figure 6-8).
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