2 Replies Latest reply on May 4, 2015 5:26 AM by eric.brown

    When to Use Multi-Slot Device vs. Hetero Type 2 Device?

    eric.brown

      Good day folks,

       

      I reviewed the info at the Technote MG583318 and found it quite helpful, especially the videos.  I am using the DxDesigner with PADS 9.5 (the ES setup).

       

      But, I am still not really sure when to set up a Hetero Type 2 part instead of using the Multi-Slot technique.

       

      Let me take a simple example.  Let's say I've got a SN74LVC2G14DCKR (Dual Schmitt Trigger Inverter) and I would like to have two ways to use this device in a schematic.  One way I may want to use it (if, for example, the circuit is simple and I want to keep the gates and Power / GND pins together) is to make a symbol like this (the PKG_TYPE Property is set to TI_DCK for me when I go to layout with PADS):

       

      Entire Device.png

       

      In this first case the issue of HETERO or Multi-Slot is not a concern.  But, now let's say for the second kind of usage I want to split the gates into two pieces.  And whether I implement the first kind of usage or the second I want the Symbol(s) to reference the same PKG_TYPE going into PADS Layout.

       

      Is it better to follow the Hetero Type 2 method, or the Multi-Slot method?  Why would I choose one over the other?

       

      In any case, I want the ability to have the PADS 'forwarding' interface assign as many packages (physical parts) as needed and I would like to preserve the ability to swap pins and gates as necesary to make the layout as clean as possible.  Also, I would want to be able to make sure Power and Ground connections are assigned for each part package.  And, of course, I need to be able to overrride those pins with the specific Power Supply I am using (might be 5 VDC in one place on the circuit and 3.3 VDC at another place althoug it is is clear to me that the Designer will need to not mix those).

       

      Many thanks for any advice and info!  Best, 
      Eric

        • 1. Re: When to Use Multi-Slot Device vs. Hetero Type 2 Device?
          robert_davies

          A bit late in the day but I've just been looking back over some old threads on the Community. In this case you would probably want to use a Hetero 4, different representations of the same device, in your case a single gate and the full package. You can mix and match them as you see fit. You would use the SIGNAL property to control the power supplies rather than physically showing them on the symbol, the values can be overridden in the schematic to the supply you require.

          It would also work as a Hetero type 2, but is not generally done for logic gates with 'regular' supply rails.

           

          Both representation would have the same DEVICE, PKG_TYPE, SIGNAL and HETERO properties, the only difference would be Parts. This would be Parts=1 for the full gate (dual representation) and Parts=2 for the single gate representation.

          2 of 2 people found this helpful
          • 2. Re: When to Use Multi-Slot Device vs. Hetero Type 2 Device?
            eric.brown

            Good morning Robert,

             

            Great, the info is very helpful because I have another Project that will benefit from it in my "pipeline".

             

            Thanks for taking the time to respond.  Best, 
            Eric