D-Latch

Discussion in 'General Electronics Chat' started by EngIntoHW, Sep 2, 2010.

  1. EngIntoHW

    Thread Starter Member

    Apr 24, 2010
    128
    0
    Hi,

    I learned about a D-latch with 2 inputs - D (data) & EN (enable) - and 2 outputs - Q and Q'.

    Is it possible to connect D and EN to each other, so when D goes to '1', '1' is transferred to the output, and when D goes to '0', the output doesn't change?
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Would that be the same as a clocked D latch?
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Not quite. The data has to be present and stable before the EN signal latches it. Presenting the D and EN at the same time may not give a good result. The same applies to dropping the levels together. Look at suggested timing for a 74LS75 as an example.

    On another level, what is the point of the latch if it to exactly represent the state of the D input? The signal of itself should be sufficient, as the operation above does not latch anything.
     
    Last edited: Sep 2, 2010
Loading...