XC3S400-4PQ208C Xilinx Inc, XC3S400-4PQ208C Datasheet - Page 29

• Manufacturer Part Number: XC3S400-4PQ208C
• Description: IC SPARTAN-3 FPGA 400K 208PQFP
• Manufacturer: Xilinx Inc
• Series: Spartan™-3r

Specifications of XC3S400-4PQ208C

• Number Of Logic Elements/cells: 8064
• Number Of Labs/clbs: 896
• Total Ram Bits: 294912
• Number Of I /o: 141
• Number Of Gates: 400000
• Voltage - Supply: 1.14 V ~ 1.26 V
• Mounting Type: Surface Mount
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 208-BFQFP
• Other names: Q2844431; XC3S4004PQ208C; XC3S4004PQ208C

Choosing the READ_FIRST attribute, data already stored in
the addressed location pass to the DO outputs before that
location is overwritten with new data from the DI inputs on
Choosing a third attribute called NO_CHANGE puts the DO
outputs in a latched state when asserting WE. Under this
condition, the DO outputs will retain the data driven just
DS099-2 (v2.5) December 4, 2009
Product Specification
R
Figure 13: Waveforms of Block RAM Data Operations with WRITE_FIRST Selected
Figure 14: Waveforms of Block RAM Data Operations with READ_FIRST Selected
ADDR
ADDR
CLK
CLK
WE
WE
DO
DO
EN
EN
DI
DI
DISABLED
DISABLED
0000
0000
XXXX
XXXX
aa
aa
READ
READ
MEM(aa)
MEM(aa)
www.xilinx.com
1111
bb
MEM(bb)=1111
1111
bb
MEM(bb)=1111
WRITE
WRITE
old MEM(bb)
an enabled active CLK edge. READ_FIRST timing is shown
in the portion of
before WE was asserted. NO_CHANGE timing is shown in
the portion of
1111
Spartan-3 FPGA Family: Functional Description
2222
cc
2222
cc
MEM(cc)=2222
MEM(cc)=2222
WRITE
WRITE
old MEM(cc)
Figure 15
2222
Figure 14
during which WE is High.
dd
dd
DS099-2_14_030403
DS099-2_15_030403
during which WE is High.
XXXX
XXXX
READ
READ
MEM(dd)
MEM(dd)
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