Help With DM74LS373N

Discussion in 'The Projects Forum' started by Marc Mello, Nov 22, 2014.

  1. Marc Mello

    Thread Starter New Member

    Nov 22, 2014
    Hello everyone

    I am making a simple program that reads data from a computer and stores it onto an EEPROM.

    Anyway, for some reason I can't figure out how to properly latch data inputs to the LS373N. I made a small test circuit with two LEDS connected to Q1 and Q2. All I am trying to do is send inputs to D1 and D2 to make sure that the Q1 and Q2 match D1 and D2.

    According to the data sheet, when g(enable) is HIGH and OC is LOW, inputs should match the outputs. However I am not getting this result. I have tried every combination of OC and g in order to see outputs matching the inputs. Nothing works.

    I am not sure what OC( actually does) and when I ground my OC, the LEDS turn ON regardless of the input status on the D's.

    Any help would be much appreciated!!
    Datasheet Link

    Thanks in advance

  2. ScottWang


    Aug 23, 2012
    1) You should adding a limited current resistor for the led if you are not doing that.
    2) Have you ever try to set the OC=Low first and send the data, waiting for a little delay for the datas became stable, and the last is to set the EN(Enable) to High.

    Or there is no delay time, just following the sequence of 2).
    Last edited: Nov 22, 2014
  3. Lestraveled

    Well-Known Member

    May 19, 2014
    OC (output control) enables the output drivers when it is low. I think for what you are doing it should be tied low all the time. C is the latch enable. When it is high, the latch is transparent, as in, what is on the input is on the output. When C goes low, the last state is held. It is a pretty simple chip.
  4. Marc Mello

    Thread Starter New Member

    Nov 22, 2014
    Thanks guys, I figured it out. I wasn't driving my inputs with anything, and thus my LED's were glowing ( I guess the output is high by default if there is nothing driving the input). That is what my confusion was.