ML365 Virtex-II Pro QDR II SRAM Mem. Board
www.xilinx.com
49
UG066 (v1.0) June 29, 2004
1-800-255-7778
Board Stackup Guidelines
R
Board Stackup Guidelines
shows a suggested stackup for a 12-layer board (4 signal layers, 6 dedicated
planes, 2 layers with both signals and ground planes).
shows the top layer of the
ML365 (Revision 1.0b) board, and
shows the bottom layer of the board.
Table 5-2:
Suggested Stackup for a 12-layer board
12-Layer
Board
Stackup#
Type
Layer
Trace / Spacing
Comments
1
Plane
GND
Gnd 1 / Sig 1
Ground plane, some memory traces
2
Plane
+2.5V/ +5V
Pwr 1
Carve out two power planes on this layer
3
Signal
+1.8V/ +2.5V
Sig 2
Some HSTL traces to the memory on this layer
4
Signal
+1.8V/ +2.5V
Sig 3
Some HSTL traces to the memory on this layer
5
Plane
GND
Gnd 2
Ground plane
6
Plane
+1.5V
Pwr 2
1.5V power plane
7
Plane
+0.9V
Pwr 3
0.9V reference plane
8
Plane
GND
Gnd 3
Ground plane
9
Signal
+1.8V/ +2.5V
Sig 4
Some HSTL traces to the memory on this layer
10 Signal
GND
Sig
5
Ground
plane
11
Plane
+1.8V & +3.3V
Pwr 4
Carve out two power planes on this layer
12
Plane
GND
Gnd 4 / Sig 6
Ground plane, some memory traces
Product Not Recommended for New Designs