SCPS286 July 2025 TPLD2001
ADVANCE INFORMATION
When used to implement a sequential logic element, the two input signals from the connection mux go to the data (D) and clock (CLK) inputs of the flip-flop or latch, with the output going back to the connection mux. This macro-cell has initial state parameters as well as clock and output polarity parameters that can be configured.
The operation of the D flip-flop/latch will follow the functional descriptions below:
The clock polarity is configurable and can be set to non-inverted (CLK) or inverted (nCLK).
Latch with nCLK: when CLK is High, then Q = D; otherwise Q remains its previous value (input D has no effect on the output, when CLK is Low).
The output polarity is configurable and can be set to non-inverted (Q) or inverted (nQ).
Table 7-18 and Table 7-19 show the truth tables for the D flip-flop and D latch, respectively.
|
CLKPOL |
CLK |
D |
Q |
nQ |
|---|---|---|---|---|
|
0 |
↓ |
0 |
Q0 |
nQ0 |
|
↑ |
0 |
0 |
1 |
|
|
↓ |
1 |
Q0 |
nQ0 |
|
|
↑ |
1 |
1 |
0 |
|
|
1 |
↓ |
0 |
0 |
1 |
|
↑ |
0 |
Q0 |
nQ0 |
|
|
↓ |
1 |
1 |
0 |
|
|
↑ |
1 |
Q0 |
nQ0 |
|
CLKPOL |
CLK |
D |
Q |
nQ |
|---|---|---|---|---|
|
0 |
0 |
0 |
0 |
1 |
|
1 |
0 |
Q0 |
nQ0 |
|
|
0 |
1 |
1 |
0 |
|
|
1 |
1 |
Q0 |
nQ0 |
|
|
1 |
0 |
0 |
Q0 |
nQ0 |
|
1 |
0 |
0 |
1 |
|
|
0 |
1 |
Q0 |
nQ0 |
|
|
1 |
1 |
1 |
0 |