LF2249
DEVICES INCORPORATED
12 x 12-bit Digital Mixer
LF2249
DEVICES INCORPORATED
12 x 12-bit Digital Mixer
DESCRIPTION
The
LF2249
is a high-speed digital
mixer comprised of two 12-bit
multipliers and a 24-bit accumulator.
All multiplier inputs are user acces-
sible, and each can be updated on
every clock cycle. The LF2249 utilizes
a pipelined architecture with fully
registered inputs and outputs and an
asynchronous three-state output
enable control for optimum flexibility.
Independent input register clock
enables allow the user to hold the
data inputs over multiple clock cycles.
Each multiplier input also includes a
user-selectable 1-16 clock pipeline
delay. The output of each multiplier
can be independently negated under
user control for subtraction of prod-
ucts. The sum of the products can
also be internally rounded to 16 bits
during the accumulation process.
A separate 16-bit input port con-
nected to the accumulator is included
to allow cascading of multiple
LF2249s. Access to all 24 bits of the
accumulator is gained by switching
between upper or lower 16-bit words.
The accumulated output data is
updated on every clock cycle.
All inputs and outputs of the LF2249
are registered on the rising edge of
clock, except for OE. Internal pipeline
registers for all data and control
inputs are provided to maintain
FEATURES
u
40 MHz Data and Computation Rate
u
Two 12 x 12-bit Multipliers with
Individual Data Inputs
u
Separate 16-bit Input Port for
Cascading Devices
u
Independent, User-Selectable 1鈥?6
Clock Pipeline Delay for Each Data
Input
u
User-Selectable Rounding of Products
u
Fully Registered, Pipelined
Architecture
u
Three-State Outputs
u
Fully TTL Compatible
u
Replaces TRW/Raytheon/Fairchild
TMC2249
u
120-pin PQFP
1
2
3
4
5
6
7
LF2249 B
LOCK
D
IAGRAM
ADEL
3-0
A
11-0
ENA
BDEL
3-0
B
11-0
ENB
CDEL
3-0
C
11-0
ENC
DDEL
3-0
D
11-0
END
8
1鈥?6
1鈥?6
1鈥?6
1鈥?6
9
4
NEG
2
CLK
NEG
1
4
10
11
RND
4
2's COMP
2's COMP
4
ACC
FT
16
3
CASEN
2:1
16
24
CAS
15-0
MS
1
16
0
0
16
1
LS
SWAP
2:1
2:1
OE
16
NOTE: NUMBERS IN REGISTERS INDICATED
NUMBER OF PIPELINE DELAYS.
S
15-0
Video Imaging Products
1
08/16/2000鈥揕DS.2249-J
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2
3
4
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