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DEVICES INCORPORATED
Multiplier-Accumulators
03/29/2000–LDS.10/2009-L
1
LMA 1009/2009
12 x 12-bit Multiplier-Accumulator
12 x 12-bit Multiplier-Accumulator
K
20 ns Multiply-Accumulate Time
K
Low Power CMOS Technology
K
Replaces Fairchild TDC1009/
TMC2009
K
Two’s Complement or Unsigned
Operands
K
Accumulator Performs Preload,
Accumulate, and Subtract
K
Three-State Outputs
K
68-pin PLCC, J-Lead
FEATURES
DESCRIPTION
DEVICES INCORPORATED
The
LMA1009
and
LMA2009
are high-
speed, low power 12-bit multiplier-accu-
mulators. They are pin-for-pin equiva-
lent to the TRW TDC1009/TMC2009
multiplier-accumulators. The LMA1009
and LMA2009 are functionally identical;
they differ only in packaging. Full ambi-
ent temperature range operation is
achieved by the use of advanced CMOS
technology.
The LMA1009/2009 produces the 24-bit
product of two 12-bit numbers. The
results of a series of multiplications may
be accumulated to form the sum of prod-
ucts. Accumulation is performed to
27-bit precision with the multiplier prod-
uct sign extended as appropriate.
Data present at the A and B input regis-
ters is latched on the rising edges of
CLK A and CLK B respectively. RND,
TC, ACC, and SUB controls are latched
on the rising edge of the logical OR of
CLK A and CLK B. TC specifies the input
as two’s complement
(TC HIGH) or unsigned magnitude
(TC LOW). RND, when HIGH, adds ‘1’
to the most significant bit position of the
least significant half of the product. Sub-
sequent truncation of the 12 least signifi-
cant bits produces a result correctly
rounded to 12-bit precision.
The ACC and SUB inputs control accu-
mulator operation. ACC HIGH results in
addition of the multiplier product and
the accumulator contents, with the result
stored in the accumulator register on the
rising edge of CLK R. ACC and SUB
HIGH results in subtraction of the accu-
mulator contents from the multiplier
product, with the result stored in the
accumulator register. With ACC LOW
and SUB LOW, no accumulation occurs
and the next product is loaded directly
into the accumulator register. ACC LOW
and SUB HIGH is undefined.
The LMA1009/2009 output register (ac-
cumulator register) is divided into three
independently controlled sections. The
least significant result (LSR) and most
significant result (MSR) registers are 12
bits in length. The extended result regis-
ter (XTR) is 3 bits long.
Each output register has an independ-
ent output enable control. In addition
to providing control of the three-state
output buffers, when OEX, OEM, or
OEL are HIGH and PREL is HIGH, data
can be preloaded via the bidirectional
output pins into the respective output
registers. Data present on the output
pins is latched on the rising edge of
CLK R. The interrelation of PREL and
the enable controls is summarized in
Table 1.
LMA1009/2009 B
LOCK
D
IAGRAM
ACC
SUB
A REGISTER
B REGISTER
REGISTER
R
CLK A
CLK B
RND
TC
12
12
24
A
11-0
R
23-12
12
B
11-0
R + A
R – A
PASS R
LEM
LEL
LEX
R
11-0
12
R
26-24
3
27
PRELOAD
CONTROL
LOGIC
3
CLK R
ACCUMULATOR
R
A
OEL
OEX
OEM
PREL
LEL
LEX
LEM
OEL
OEX
OEM
OEX
OEM
OEL
3
27
3
12
12