
PRODUCT SPECIFICATION
TMC2249A
6
REV. 1.0.2 7/6/00
Controls
ENA-END N13, N2, C12, 
A3
60, 33, 89, 116
Input Enables.
are latched into delay pipeline i, and data already in pipeline i 
advance by one register position, on each rising edge of CLK for 
which ENi is LOW. When ENi is HIGH, the data in pipeline i do not 
move and the value at the input port i will be lost before it reaches 
the multiplier.
Negate.
 The products of the multipliers are negated causing a 
subtraction to be performed during the internal summation of 
products, when the NEGate controls are HIGH, NEG1 negates the 
product A x B, while NEG2 acts on the output of the multiplier which 
generates the product C x D. When the length controls ADEL–
DDEL are set to zero, these controls indicate the operation to be 
performed on data input during the same clock. As nonzero values 
for ADEL–DDEL do not affect the pipelining of these controls, their 
effect is not synchronous with the data input in these cases.
Round.
 When the rounding control is HIGH, the 24-bit sum of 
products resulting from data input during that clock is rounded to 16 
bits. When enabled rounding is automatically performed only during 
the first cycle of each accumulation sequence, to avoid the 
accumulation of roundoff errors.
Feedthrough.
 When the Feedthrough control is HIGH, the pipeline 
delay through the cascade data path is minimized to simplify the 
cascading of multiple devices. When FT is LOW and ADEL through 
DDEL are all set to 0, the data inputs are aligned, such that 
S(n+6) = CAS(n) + A(n)B(n) + C(n)D(n). See Table 2.
Cascade Enable.
 Data presented at the cascade data input port 
are latched and accumulated internally when the input enable 
CASEN during that clock is LOW. When CASEN is HIGH, the 
cascade input port is ignored.
Accumulate.
 When the registered ACCumulator control is LOW, no 
internal accumulation will be performed on the data input during the 
current clock, effectively clearing the prior accumulated sum. When 
ACC is HIGH, the internal accumulator adds the emerging product 
to the sum of the previous products and RND is disabled.
Swap Output Words.
 The user may access both the most and 
least-significant 16 bits of the 24-bit accumulator by utilizing SWAP. 
Normal operation of the device, with SWAP = HIGH, outputs the 
most significant word. Setting SWAP = LOW puts a double-register 
structure into "toggle" mode, allowing the user to examine the LSW 
on alternate clocks. New output data will not be clocked into the 
output registers until SWAP returns HIGH.
Output Enable.
 Data currently in the output registers is available at 
the output bus S
15-0 
when the asynchronous Output Enable is LOW. 
When OE is HIGH, the outputs are in the high-impedance state.
 Input data presented to port i11-0 (i=A,B,C, or D) 
NEG1,2
B1, D3
3, 4
RND
C2
5
FT
E11
84
CASEN
D13
83
ACC
B2
2
SWAP
K3
28
OE
M1
27
No Connect
L12
D4
65
Do Not Connect
Index Pin (optional)
Pin Descriptions 
(continued)
Pin Name
Pin Number
Pin Function Description
CPGA/PPGA/
MPGA
MQFP