LDP

Transparent Data Latch with Asynchronous Preset

LDP is a transparent data latch with asynchronous preset (PRE). When the PRE input is High, it overrides the other inputs and resets the data (Q) output High. Q reflects the data (D) input while gate (G) input is High and PRE is Low. The data on the D input during the High-to-Low gate transition is stored in the latch. The data on the Q output remains unchanged as long as G remains Low.

The latch is asynchronously preset, output High, when power is applied. Virtex simulates 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_VIRTEX symbol.

Inputs			Outputs
PRE	G	D	Q
1	X	X	1
0	1	0	0
0	1	1	1
0	0	X	No Chg
0		D	d
d = state of input one setup time prior to High-to-Low gate transition