D-latch & edge-triggered D-type flip-flop

[qwerty159]

The difference between a D-latch and an edge-triggered D-type flip-flop is that the latch:

A)
is controlled by the logic level at its ENABLE input rather than a CLK transition.
B)
always "latches" the Q output to the D input regardless of other inputs.
C)
triggers on either the rising or falling edge of an ENABLE signal rather than the CLK input logic level.


Thanks..I had a test and this is the only one I got wrong. I can't figure out this one.

[pebe]

Hi qwerty,

I don’t agree with answers that were given to you.

All the D-latches I have seen use a Data pin and CLK pin. The RS latch has two data input pins – a Set and a Reset. The CLK pin, when activated, copies the state of the Data on to the Q output. The latch may, or may not, have an Enable pin. If it has, the latch is only operative when the Enable pin is active.

I have never seen a case where Enable triggers a latch – it only enables an action to take place.

This site deals very well with the subject.
http://www.play-hookey.com/digital/cloc ... latch.html
http://www.play-hookey.com/digital/d_nand_latch.html