FDRSE_1

D Flip-Flop with Negative-Clock Edge, Synchronous Reset and Set, and Clock Enable

FDRSE_1 is a single D-type flip-flop with synchronous reset (R), synchronous set (S), and clock enable (CE) inputs and data output (Q). The reset (R) input, when High, overrides all other inputs and resets the Q output Low during the High-to-Low clock transition. (Reset has precedence over Set.) When the set (S) input is High and R is Low, the flip-flop is set, output High, during the Low-to-High clock (C) transition. Data on the D input is loaded into the flip-flop when R and S are Low and CE is High during the High-to-Low clock 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
R	S	CE	D	C	Q
1	X	X	X		0
0	1	X	X		1
0	0	0	X	X	No Chg
0	0	1	1		1
0	0	1	0		0