XC3S400-4FT256C Xilinx Inc, XC3S400-4FT256C Datasheet - Page 30

• Manufacturer Part Number: XC3S400-4FT256C
• Description: SEMI CONDUCTOR
• Manufacturer: Xilinx Inc

Specifications of XC3S400-4FT256C

• Case: BGA
• Dc: 04+

Spartan-3 FPGA Family: Functional Description
Dedicated Multipliers
All Spartan-3 devices provide embedded multipliers that
accept two 18-bit words as inputs to produce a 36-bit prod-
uct. This section provides an introduction to multipliers. For
further details, refer to the “Using Embedded Multipliers”
chapter in UG331.
The input buses to the multiplier accept data in two’s-com-
plement form (either 18-bit signed or 17-bit unsigned). One
such multiplier is matched to each block RAM on the die.
The close physical proximity of the two ensures efficient
30
54
A[17:0]
B[17:0]
Figure 15: Waveforms of Block RAM Data Operations with NO_CHANGE Selected
(a) Asynchronous 18-bit Multiplier
ADDR
CLK
WE
DO
EN
DI
DISABLED
MULT18X18
0000
Figure 16: Embedded Multiplier Primitives
XXXX
aa
READ
P[35:0]
MEM(aa)
www.xilinx.com
1111
bb
MEM(bb)=1111
WRITE
data handling. Cascading multipliers permits multiplicands
more than three in number as well as wider than 18-bits.
The multiplier is placed in a design using one of two primi-
tives: an asynchronous version called MULT18X18 and a
version with a register called MULT18X18S, as shown in
Figure 16a
these primitives are defined in
The CORE Generator system produces multipliers based
on these primitives that can be configured to suit a wide
range of requirements.
A[17:0]
B[17:0]
RST
CLK
(b) 18-bit Multiplier with Register
CE
2222
cc
MEM(cc)=2222
WRITE
and
Figure
MULT18X18S
16b, respectively. The signals for
dd
DS099-2_16_030403
XXXX
READ
MEM(dd)
Table
DS099-2 (v2.2) May 25, 2007
P[35:0]
DS099-2_17_052705
14.
Product Specification
R