Xilinx Virtex-4 ML455, User Manual

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14 www.xilinx.com Virtex-4 ML455 PCI/PCI-X Board
UG084 (v1.0) May 17, 2005
Chapter 3: Hardware Description
R
DDR SDRAM SODIMM Memory
The ML455 board contains a 200-pin, small-outline dual in-line memory module
(SODIMM) connector (J4) that supports installation of DDR SDRAM SODIMM memory
modules of 128 MB, 256 MB, 512 MB, or 1 GB. Xilinx provides a 128 MB memory SODIMM
Micron Semiconductor part number MT8VDDT1664HDG-265B3, with the kit.
Table 3-2
provides a description of the memory interface signal descriptions, SODIMM connector
pin assignments, and associated FPGA pin assignments.
The ML455 board does not support a 72-bit DDR data interface required for parity or error
correction codes (ECC).
Characteristics of the DDR SDRAM SODIMM (provided with the kit):
•
Organization 16M x 64 bit
•
Memory clock speed 7.5 ns/133 MHz
•
CAS latency 2.5
•
2.5V I/O (Stub-Series Terminated Logic (SSTL2) compatible)
The data sheet for the DDR SDRAM Small Outline DIMM memory module kit can be
obtained from Micron Semiconductor at
www.micron.com/products/modules . Contact
Micron for availability of other compatible products, including device capacity, clock
speeds, and CAS latency options, in the 200-pin SODIMM form factor.
The ML455 board memory interface design includes on board 50
Ω
termination resistors to
V
TT
, at both the FPGA and SODIMM ends of the interface, for the 64 bit bidirectional DQ
data-bus and the 8 bit bidirectional DQS signals. The address and control signals have 50
Ω
termination resistors to V
TT
at the SODIMM end of the interface. The SODIMM provides a
120
Ω
termination network for the differential clock inputs. The Xilinx Digitally Controlled
Impedance (DCI) standard SSTL2_I_DCI can be utilized to terminate unidirectional
address and control signals transmitted by the FPGA. External 50
Ω
reference resistors are
provided to VRN and VRP for the memory interface banks 7 and 8 of the XC4VLX25
FPGA. See the Virtex-4
User Guide for additional information on DCI.
Table 3-2: SDRAM Memory Interface Signal Descriptions
SODIMM
Signal
XC4VLX25 SODIMM
Signal
XC4VLX25
J4 Pin # U10 Pin # J4 Pin # U10 Pin #
112 A0 AE21 89 CK2 AC25
111 A1 V6 91 CK2_B AC26
110 A2 AE18 96 CKE0 AC18
109 A3 W1 95 CKE1 AB23
108 A4 AF18 12 DM0 Y19
107 A5 W2 26 DM1 AA18
106 A6 AF22 48 DM2 AB21
105 A7 AD23 62 DM3 Y17
102 A8 AF21 134 DM4 AF5
101 A9 AD22 148 DM5 AD4
115 A10 V5 170 DM6 Y10
100 A11 AB18 184 DM7 AE6
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