Libraries GuideChapter 5: Design Elements (F5MAP to FTSRLE)
FDE
D Flip-Flop with Clock Enable
XC3000
| XC4000E
| XC4000X
| XC5200
| XC9000
| Spartan
| SpartanXL
| Spartan2
| Virtex
|
|---|
N/A
| N/A
| N/A
| N/A
| N/A
| N/A
| N/A
| Primitive
| Primitive
|
FDE is a single D-type flip-flop with data input (D), clock enable (CE), and data output (Q). When clock enable is High, the data on the D input is loaded into the flip-flop during the Low-to-High clock (C) transition.
The flip-flop is asynchronously cleared, output Low, when power is applied. Virtex and Spartan2 simulate power-on when global set/reset (GSR) is active. GSR defaults to active-High but can be inverted by adding an inverter in front of the GSR input of the STARTUP_SPARTAN2 or STARTUP_VIRTEX symbol.
Inputs
| Outputs
|
|---|
CE
| D
| C
| Q
|
|---|
0
| X
| X
| No Chg
|
1
| 0
| 
| 0
|
1
| 1
|
| 1
|
