24
Virtex-4 ML455 PCI/PCI-X Board
UG084 (v1.0) May 17, 2005
Chapter 3:
Hardware Description
R
DDR Memory Bus Termination Module
The ML455 board has an onboard 2.5V 200-pin DDR SODIMM socket. The SODIMM
provided with the ML455 is the Micron 128 MB MT8VDDT1664HDG-265B3, organized as
16M x 64. The data sheet for this SODIMM is located at
.
The linear voltage regulator U2 provides the 2.5V required by the SODIMM. The memory
interface also requires a termination resistor network, typically driven by memory V
DD
/2.
The 1.25V V
TT
termination supply VR1 is a TI PTH0505Y-AH switching source/sink
reference module capable of handling 6A (see
). A resistor divider network (two
1 K
Ω
1% resistors in series) is applied to the U2 2.5V output to create the 1.25V reference
module input voltage. The module output closely tracks the input.
The data sheet for the TI module is located at
http://focus.ti.com/docs/prod/folders/print/pth05050y.html
.
64-bit PCI Edge Connector
shows the edge connector pin assignment (the component side of the PCB is
side A, and the non-component side or the back of the PCB is side B).
Figure 3-8:
PTH0505Y-A V
TT
Termination Supply
DDR1_VREF
5V
2.5V
VR1
TI PTH0505Y
P10
C21
330
µ
F
+
C22
330
µ
F
+
1
2
3
4
6
5
R237
1K
R228
1K
VIN
INHIBIT
VREF
GND
VOUT
NC
UG084_c3_07_020405
Table 3-11:
P1 PCI Edge Connector Pinout
P1 A Side
Signal
P1 B Side
Signal
32-Bit Connector
A1
unused
B1
VCC_MINUS12
A2
VCC12
B2
unused
A3
unused
B3
GND
A4
EDGE_JTAG
B4
EDGE_JTAG
A5
VCC5
B5
VCC5
A6
EDGE_INTA_B
B6
VCC5
A7
EDGE_INTC_B
B7
EDGE_INTB_B
A8
VCC5
B8
EDGE_INTD_B
www.BDTIC.com/XILINX